What will happen with Blender 2.8 game engine? Blender has just purged the entire game engine from 2.8. There is no "Game Engine" mode anymore and there isn't even a logic editor. I tried installing a GitHub Blender release with the game engine mode working but it failed to install because all the game code was gutted. Does this mean that Blender 2.8 is going to lose the game engine, or is the game engine just being redone for better compatibility and whatnot?

As far as we know the Blender Game engine has been removed from official Blender releases for good, at least in its old form. As of commit 159806140fd3 - Removing Blender Game Engine from Blender 2.8 on April 2018, BGE is no more, along with other "aging" components like the Blender Internal Render Engine viewport drawing code among others.
Ton Roosendaal himself was given the honor of making the commit that put the old code to rest.

As for the reasons for removal we can conclude it was an old and aging component, it was largely unmaintained, suffered from several bugs and limitations, and the Blender Foundation probably lacked the energy, motivation and manpower to maintain it properly.

Adding new things to Blender gets much easier that way. The Blender
Internal code started in early 90s. Over 25 years old! Functionally,
EEVEE can (and will) completely replace it.
Ton Roosendaal

It was also very architecturally outdated, lagged severely behind the current industry standards and modern technologies in many ways, it would be very hard to bring it up to date. Modernizing it or introducing new features would end up being more work than a full rewrite from scratch.
For that reason they decided to release Blender from these "metaphorical shackles" holding it back; making it easier to move forward and update other more important and frequently used features.
This frees Blender developers to work on other things, allowing more manpower to be redirected to truly useful new features like a better viewport drawing code, a modern layer system, a better dependency graph, usability improvements, among others. These will instead help you produce better game assets (which is Blender's main focus, and where its greatest strength lies anyway), rather than trying to run the game itself, leaving that role to dedicated engines.
"Why wont they make a new one then?"
Probably both because "we are too late to the race" and it would be a tremendous amount of work to write one well. There are already a number of well established third party game engine solutions out there, both free, open source, or comercial; and competing with those would be extremely hard and pointless.
Writing a full game engine is no small task, it is a full time job on its own, and maintaining it well would require a lot of continued manpower and resources. Since expectations are very high (supporting multitude of hardware and environments, multi-platform publishing, modern physics, logic systems, networking, security, smooth performance, and all the modern commodities expected of contemporary game engines) it would probably always end up feeling inferior or lacking in lots of ways compared to more mature established competitors.
What About Forking It?
UPBGE is a third party fork, whose objective is updating and modernizing the BGE with better technologies and features, with the end goal of eventually merging it back with main Blender development branch.
I fear its future is uncertain at this point unfortunately. While I believe Blender developers won't actively do anything to purposefully break Blender trunk codebase compatibility, I speculate it will naturally become increasingly hard for UPBGE developers to maintain their code working, as features are removed and main Blender development deviates further from the current design.
UPBGE will probably continue to work as standalone based against current 2.79 versions for any foreseeable future, but you will likely miss all the other improvements made in subsequent versions.
While the final decision is always yours, as it stands your time is probably best spent learning something else more ubiquitous and modern, giving you a more lasting and future proof investment.
So, is it really gone for good?
In its current form yes.
There have been talks about replacing the old game engine with a newer better integrated "Interactive Mode". It would be a more integral part of Blender, as opposed to a separate component with a lot of duplicated code that re-implemented a very limited subset of supported features we currently have.
This is not meant to be a direct replacement of the old BGE, nor a discrete game engine in the traditional sense with wide publishing capabilities, rather more of an integrated real-time "presentation tool" or interaction mode with a physics simulation sandbox environment, that runs directly inside Blender's viewport on currently supported platforms.
On 28 May 2018 Ton Roosendaal announced in the Developers Mailing list that a portion of the 2.8 Code Quest funds were reserved for the development of a new and improved real time rendering system or "Interactive Mode" and Benoit Bolsee, a developer historically known for his involvement in real time side of Blender, accepted a grant to work part time on this for one year.
I speculate this will probably feature a new node based workflow and logic system,  real time physics, and integrate well with other upcoming features like "Object Nodes" also known as "Everything Nodes" in one way or another.
When will it be ready?
A project of this magnitude requires a lot of careful planing and design to get done right, this will lay solid foundations on which to work on. On top of that there is still the huge amount of work required to actually implement it and get it working, tested and stable enough for the general public.
This would take a dedicated team working full time a long time to get done, it will take even more for a single person to do it alone.
Since Benoit is only working on it part time and for a relatively short period of one year, this is likely still very far away in the horizon.
As of 2020 development seems to be indefinitely on standby, probably waiting on  solid planning, development of required dependencies and maturing of current features. There are currently no predictions of when or if it will ever be resumed.
If you would like to help and can't code, you can contribute to the Development Fund. This will allow hiring more full time developers to work on newer features. Have in mind that there is no guarantee this will specifically direct funds dedicated to Interaction Mode, but they might get there faster. And if there is enough interest maybe a full time developer slots can be allocated for these tasks.
So what do I do now?
Though BGE is going away for future versions nothing stops you from continuing using it under Blender 2.79 or UPBGE for the foreseeable future, as long as they work in current hardware and operating systems.
If you are spending time and resources learning the craft, you might as well invest it on something popular and well accepted in the industry, with a bigger audience and wider reach. Learning resources will likely be more abundant, and it might even increase your future employability, if you seek to work in the industry.
There are many third party game engines out there, good for many different purposes and workflows, and for varying "wallet sizes". Some integrate very well with Blender, even using its native UI (like the Node Editor through PyNodes) for editing a varying subset of supported features and functionality.
They also provide extended publishing capabilities, reaching many platforms never before supported by Blender Game Engine (like mobile devices, web, cross platform development, among others).
The best known and most well established ones are probably:

Unreal Engine
Unity
Uniengine - Focus on real time presentations for industry and enterprises
CryEngine
Lumberyard - Amazon's Open Source version of the CryEngine

There are also free and open source solutions that integrate very well into Blender pipeline and native UI like:

Godot - Well established free alternative, 2D graphics focus, popular for mobile content.
Armory 3D - Relatively young entry, actively maintained, free and open source license.
Urho3D - As pointed out by user Kabu in the comments
Ogre 3D -  One of the oldest open source engines around, since 2001

While not a game engines per-se, products like Blend4Web and Verge3D provide Blender addons for web publishing that also have some form of node-based logic systems and scripting capabilities. These allow creation of basic behaviors, and a certain degrees of interactivity, thus providing a simplistic yet relatively capable web browser based game creation solution.


rigify generate problems rigify generate my rig like "not in the right place", it doesnt generate it right at the meta rig position. i've set the meta rig origin to the centre (didnt work) and also beteen the leg(even worse). sometimes the rig itself doesnt even show up when i generate it. there's a error report at top-right corner, like this

as you can see, the rigify generate the rig above the meta rig, and the report a"auto-run disabled....." any solutions ?

That is a security feature, click the "Reload Trusted" button right to the error message. To permanently allow script execution  change the user pereferences accessible from the file menu:

Auto-run scripts security options


make invisible depending on point of view suppose I have modelled a room like that:

when I look at it from outside like in screenshot, I want the walls whose normals are not going towards my point of view to go transparent. In other words, I want to see the insides of the room so that the walls at which I am looking from outside, go transparent. see the screenshot for illustration, I have just hidden those faces

when I change my point of view, other faces have to go transparent while others become visible.

I think that must be somewhere on the surface but as always my Google skills are too bad to find out

Assuming that the room's normals point inwards, you can accomplish this by using the Geometry node, a Mix Shader and a Transparent BSDF.

Connect the Backfacing socket of the Geometry node to the Fac socket of the Mix Shader node. Next connect your actual material nodes to the upper Shader input of the Mix Shader node and the Transparent BSDF to the lower one.

This effectively creates a backface culling material.

If you're using Eevee, you will also have to set the Blend Mode and Shadow Mode to Alpha Clip or Alpha Hashed. In case you're only using Eevee and don't need a material for Cycles, you can enable the Backface Culling option (above the Blend Mode) instead of using the node setup.

Don't forget to add lights inside the room.

If you only want this for the viewport, then you can enable Backface Culling in the Viewport Shading options.


Weight painting mode right click action differs from time to time Anyone know why sometimes when you weight paint a rigged model, right click selects the bone and allows you to rotate it, while other times, it kicks you out to object mode even if you right click the exact same spot?

If the armature is in pose mode, and you select the skinned object, it will let you pose the armature if you select any bone. On the other hand, if the armature is in object mode it will take you back to object mode.

Actually, this is standard for all objects in that selection by right-clicking in the viewport will put the viewport in whatever mode that object was last in.

Note that selecting another object in edit mode or particle edit mode will not work.


How do I increase the 'View Orbit' amount? I would like to change the amount of degrees per orbit whenever I press the Numpad 4 or Numpad 6 keys from 15 to 22.5 degrees.

How would I do this?

The setting of the short cuts can be found in the user preferences, input tab.

Their names are 'view orbit'. The tricky thing is that the values needs to be in radians.

But you can use Python (transparently) to define the value you want in degrees. So to have 22.5 degrees, type "pi/8".

Now you can orbit with the wanted rotation :

Edit : you can also type "radians(22.5)". It seems all the math functions (math Python module, probably) are available.


Animation Nodes: How to create a stagger-to effect for pre-existing objects (no instancing)? I'm trying to create a stagger-to effect for pre-existing objects.
I have five placeholder objects like so:

But when I set up the animation nodes, all object transformations are reset to 0,0,0:

The rotation animation does still work as expected, but without taking into account the original transformation of the objects.

This issue does not happen when working with the Separate Text Objects node instead of the Create Object List node. In that case, each objects position is retained:

What am I missing?

I found the answer here:
https://blender.stackexchange.com/a/109017/23161

As Omar Ahmad pointed out in the comment, the objects need to have AN initial transforms set.


Bone heat weighting failed to find solution for one or more bones (tried all fix, don't work) I've modeled with guy this week and I wanted to rig it, but I got this error. I've tried all the fixes I've founded (remove doubles, deleted constraints, delete modifier, add and apply decimate modifier, etc.).

Here is the blend file:

So I separated all objects and parented each one by one and it seems that the belt and torso are the issue. I tried to recalculate the normals and Remove doubles, but it seems that there is something wrong with the two. Maybe try Retopo-ing the the two. Also for whatever reason there is no weight appearing in the weight paint mode which brings me to the conclusion that you will have to manually weight paint the model after fixing the two objects of course.

Additionally I looked up the issue and found a concise list of the stuff you need to check in your model on a reddit forum Here it is:

Anything that has lots of intersecting meshes seems to bork the auto weightpainting. If you separate loose parts, weight all the parts, and then join them, you can get an approximate weight painting.
Other things worth checking
-Are the rig and mesh aligned on the axis properly?
-Have you applied scale and rotation on everything you're weighting?
-Did you make sure to keep the x - axis mirror option on when rigging? The weight painting gets wonky when things are less symmetrical.
-Have you removed double vertices, checked your mesh for bits that don't aren't connected, and recalculated normals?
-Is your mesh or armature too large? Sometimes scaling it down can help.
That error message is frustrating because it gives very few clues as to what you're doing wrong.

Here is the file:


Keep edge loops in triangle face? Look at this picture, I have to fill the empty vertices.

The shape the face I have to fill is triangle. I can't keep edge loops after adding triangle faces, is there a way to avoid using triangle in this situation and keep edge loops work?

Something like this can split triangle into quads, just cut it with Knife tool K. But geometry will become densier in this place.

P.S. Also, I want to mention that if you are doubting how to subdivide something to quads - use Subsurf Modifier set to Simple mode (Simple - because we need to keep original curvature without smoothing). This is easy and absolutely non-destructive way to see how it can be done. So, add modifier and set viewport shading to wireframe Z and don't forget to enable Draw all edges in object settings.


How to create a procedural brick texture for a simple building without object size changing the texture size? I want to create some procedural textures that I can quickly reuse to texture objects.  For this example I want four sided cubes (ignore top and bottom) that are wrapped in bricks.

But, I want the bricks across different objects to be the same size, even if the objects are different sizes. You will notice in the image above that the "large building" is twice the size of the "small" building and the large building's bricks are also twice the size. I believe this is because the procedural texture in "UV mode" is based on the bounding size of the object, so the brick size does not change regardless of if the scale is normalized.  If I use the object node option, but that will not wrap the bricks around the cube. The only way I know to wrap the bricks is to use the Texture Coordinate node and UV as an input.

Here is my material setup.

I think the key would be to use some math so the input value nodes to the brick height and width nodes are based on the object bounding box size, but I don't know how to get this as an input to modify my brick size.

I also tried using a different object for the "object node" in the Texture Coordinate node, but the bricks did not wrap.
Thanks.

When I read Rich Sedman's first answer, I realized that what he does with the two materials can be solved with a single material using a trick called triplanar mapping.

What is the problem here? 3D procedural textures can be made size-independent using Object coordinates, but the brick texture is only a 2D procedural texture, so it does not wrap around the mesh.

What is triplanar mapping? A 2D texture is projected along the X, Y, and Z axes, and then we blend among these based on the angle of the currect face. It is used mostly for things like terrains, rocks, tree trunks but can be also used here (assuming that the faces are either in the XZ or in the YZ planes, so that we don't get blending artifacts). Cycles does not have built-in triplanar mapping support, but one can construct it from nodes, an example is here: http://www.blendswap.com/blends/view/78446

The following is a simplified version of the blendswap material, because in this case we only need two projections (X and Y - this is strictly speaking biplanar mapping), and I also took out the mapping nodes because the scaling can be tuned in the brick texture. Note however, that the mapping nodes could be useful to reduce the discontinuity at the edges, as in Rich's answer.

The nodes:

The result:


How to lock camera to Follow automatically and rotate only on command without scripts, empties I see a lot of people being suggest scripts or using as empty or track object (constraint), but the problem with Blender is it follows everything the object its a Child to (when object moves that is fine, but if the object rotates the camera rotates too).

The only thing I haven't tried is making the camera Parent, so that way the object moves with camera, but that means I have to move the camera to move the object.

Instead of parenting, try a Copy Location constraint. Enabling the offset option allows the camera to follow the object at a set distance and it will ignore any rotation of the object it is following.


how do you change material during animation ok so im making something that has an on-off switch and to start the animation i want the switch to move, go from red to green, and then turn. on, i've gotten the movement down pat, but idk how to get it ti change from red to green.

If you're using Nodes, you could use a Mixshader and animate the Value to change the material: 0 for one material and 1 for the other.


Can duplicated objects be given a separate material? I duplicated a model, but when I change color of one of the duplicated models, they both change color. I tried looking up how to separate them to color them differently but couldnt find anything.

Link your material to Object instead of object data. This drop menu is in the picture. By default it is set to Data

If you do it you need to set a new material.


Why can't I set the object on a many modifiers? In this specific case, I'm trying to apply an armature modifier but when I click on the dropdown menu no object names show up (see image), if I try to select the object with the eyedropper it says "failed to set value" if I press apply it says "modifier disabled, skipping apply" how do I get the modifier to work?

In the object drop down menu of the armature modifier, you can select armature objects (bones), and not mesh objects.


How to have the texture of a circle separated in bands each with a different factor (or color) in a shader? I created a simple shader to subdivide a circle in a specified number of bands. Each bands has a number between 0 and 1 and the factor (color) for each band is (previous bands + 1/NumberOfBands); I would like to know if there is a way to obtain a random number for each band ( between 0 and 1 possibly ) i.e. a number not related to the previous (or the following) band.
It would be perfect a node that output a random number with a seed option, and I can plug the color in the seed, any one know if there is an addon for that?

Since most earlier answers to this question, Blender has provided a discontinuous White Noise texture node. Even the smallest change in its 'coordinate' will produce a completely new output in the 0-1 range...

.. so your seed can simply be an addition to the 'W' input of the 1D version.

Here, keyed, but could be driven by #frame, location, or whatever is appropriate to your case.


Did I download Blender correctly, or was it CG Cookie? I downloaded Blender yesterday (or so I thought). When I click on the icon this morning, all I get is the beginning screen of a tutorial from CG Cookie.

Who is CG Cookie and how do I have them? How do I get Blender and the initial page I had when I first finished downloading it?

Try downloading Blender from this page https://www.blender.org/download/.

Make sure you get the correct version for your operating system.

You can also download a program file that does not require installing by downloading the zip.

Simply unzip the folder to your desktop, and run the program (it will be the file "blender" and will be a program file. [or application/executable, depending on your os.])

Or you can download the "bleeding edge" test builds from here. It is the most recent version of Blender, and is a kind of test build, so be ware, it may not be stable.


How to make a semi-realistic metalic texture/material I just finished my tank 3d model but i dont know how to go with the texture/material.I would like to create a semi realistic metal texture with bumpmaps and other things that come with metal materials.The problem is that anywhere i search online i cannot find a free way to get such a texture/material.Everything i would like to use is behind a paywall,thus im looking for a alternative.How hard is it to create a semi-realistic texture/material with a photo editing software?

There are many ways to do this.  Here's one that requires very little work, but gives you very little control:

Either find a photograph on line that you like or create one of your own.  You can use it as the basic image texture and, by processing its colors, to create the other maps.  There are a lot of things you can do, but here is a simple example node group, using a texture I grabbed from textures.com. Note that I deliberately exaggerated the effects so they would be obvious. I also used an HDR from sIBL.

The basic idea is that you turn the image into a black and white image and use the black and white image as the map you want.  Here I simply used color ramps to enhance the contrast.

EDIT: (I forgot this paragraph) The first three photographs are quick renders of just the image, the image + fake roughness map, the image + roughness and bump maps.

A second approach is to do the same thing, but to use tools outside Blender to create the other maps.  Crazy Bump has been mentioned.  You can also use your favorite photo editing program.

A third approach is to create your own textures procedurally. It would take an

The second and third approach require that you climb learning curves, but in the long run, both give you a lot of control over your own maps.

Finally, some of the commercial texture sites offer all of the necessary maps and provide free versions of some of them as an enticement.


BPY, how to select and separate one side of a road-like mesh with Python script? I would like select left or right side of mesh like this and separate it from the object using script. Is it possible? Thanks in advance.

Bmesh version

Most edges in the middle of the road have 2 linked faces, and each edge vertex 4 linked edges. (as pointed out in other answer the non-non-manifold)

middle = [e for e in bm.edges if len(e.link_faces) == 2
        and all(len(v.link_edges) == 4 for v in e.verts)]

for e in bm.edges:
    e.select = e in middle

Which gives this result, the middle of the road selected without the ends.

Use middle edges to rip the mesh with bmesh.ops.split_edges. If there are any vertices left that have 5 link edges they are on the tip of the rip.

The two rip edges in the verts link edges will also be in the ret['edges'] list returned by the operator.

An edge vector is made from one of the rip edges. The edge to rip is chosen as the one with the smallest angle to rip edge vector. Could possibly use a mesh select operator here, feel I'm missing something as seems overly complicated

Here is a bmesh script to run in edit mode for testing.  After running the road mesh will be ripped down the centre line.

import bpy
import bmesh

context = bpy.context
ob = context.object
me = ob.data
bm = bmesh.from_edit_mesh(me)

middle = [e for e in bm.edges if len(e.link_faces) == 2
        and all(len(v.link_edges) == 4 for v in e.verts)]

ret = bmesh.ops.split_edges(bm, edges=middle)
edges = set(ret["edges"])
ends = []
for v in bm.verts:
    if len(v.link_edges) == 5:
        link_edges = set(v.link_edges)
        cut = edges.intersection(v.link_edges)
        link_edges -= cut
        e = cut.pop()
        v = e.verts[1].co - e.verts[0].co
        def angle(edge):
            return v.angle(edge.verts[1].co - edge.verts[0].co)
        ends.append(sorted(list(link_edges), key=lambda e: angle(e))[0])
if ends:
    bmesh.ops.split_edges(bm, edges=ends)

Seeing this test script is for edit mode can now run

bpy.ops.mesh.separate(type='LOOSE')

To avoid any edit mode operators (so the script can be used on multi meshes in object mode) try the get_islands(...) method.


export particle mesh to unreal engine 4 Does anyone know a way to export a particle mesh animation to unreal engine using alembic for example. Or perhaps a way to bake it to a fbx animation.

I know you can convert the particles into a mesh but you loose the animation data of the particles when you do that.

Found a way here Convert particle system to animated meshes

This solution is not perfect. The euler rotation of the particles is not captured perfectly and the workflow to export to unreal is a bit tricky and "crashy".

When you export to fbx make sure you only select a single mesh as more than a couple might crash unreal engine on import. But the interesting thing is that there are multiple animations stored. So you can duplicate the mesh in unreal and select a different animation to create a flock of birds for example. It's no where near as good as the blender particle animation but good enough for a variety of applications.

Hopefully someone else can provide a better solution.


Unable to run Blender 2.8 beta on Raspbian Buster I recently bought a Raspberry Pi 4 (4GB). I wanted to test Blender 2.8 on it, but I am unable to get it running.

If I install the 2.79 stable version from the app store or terminal, it works perfectly. However, I am unable to run the Blender 2.8 beta.

I extracted the archive and double clicked on the blender binary, but its not running. I tried copying the extracted files to /usr/bin/ or /usr/local/ and tried running it again, but, still its not running.

Unlike ubuntu, in Raspbian Buster, the binary doesn't have the option to enable 'run as a program'. Tried running from terminal using ./blender, but still nothing happens. Shows 'exec error: unable to execute binary'

Raspberry Pi 4 has arm7l (32 bit) architecture. But, both the 2.79 and 2.8 builds (32 bit) don't seem to work.

Any ideas on how to get 2.8 running?

Blender 2.80 requires at least OpenGL 3.3 to run its UI. I don't think Raspberry Pi 4 supports that. It says:

  OpenGL ES 3.0 graphics

at https://www.raspberrypi.org/products/raspberry-pi-4-model-b/specifications/

That does not look like OpenGL 3.3 to me.

As for 2.79, maybe you are not trying the correct build suitable for ARM processors. See this answer.


Why is my script to add large batches of objects so slow? v2.90 I have to create about 30,000 spheres and I notice that even adding a 1000 is already a lot of work for Blender. I've cut down (hopefully?) on work and memory usage by creating just 1 mesh and 1 material for the batch, but I'd like blender to remain responsive during the batch job. Is there a way to update the UI, or an all together more recommended way of adding such a large number of objects? I will need to individually animate them.
# Creates a collection to store all the objects in.
collection = create_collection(scaffold, name)
mat = bpy.data.materials.new(name=name)
mat.diffuse_color = (1, 0, 0, 1)
# Creates an icosphere mesh
mesh = _create_ico_mesh(scaffold, name, radius)
for cell in cells:
    cell.object = obj = bpy.data.objects.new(name=f"{name} #{cell.id}", object_data=mesh)
    obj.location = cell.position
    obj.data.materials.append(mat)
    collection.objects.link(obj)

Even just being able to add the spheres one by one in a very slow fashion would be OK, right now Blender is unresponsive.

This is due to the material.
As all your objects share the same data, adding the material will add many material slots to the same data. This is visible in the material property of the object: give it a try with n = few objects.
You'll see, for each of them (as same data) n material slots added:

So, remove the line:
object.data.materials.append(mat)

If you want this mat, add it previously to the ico mesh data or add it once after the loop:
mesh.materials.append(mat)

30k objects should be around 1mn (depending on your configuration).


Why do my properties show up as '[string contents] not found' during debug? Im pretty new to the BGE and Im just getting to grip with Logic bricks

I recently attempted to create a property named Next (String) that holds the word Up, Down, Left or Right inside it depending on user inputs.

My problem is that Up is the default starting direction which seems fine; although as soon as I attempt to change it it becomes [Up/Left/Right/Down not found].

It seems like this problem is effecting other parts of logic that refer to the Next variable.

I guess I'm a little idiotic for not noticing but I've found my own answer and I guess I should leave it here for future reference!

When changing a strings data the word needed to be stored inside quotation marks (e.g -  "Up") or it won't work, hope this helps someone in the future.


Clothes don't collide to its parent : a rigid body Description of my scene :
I have a human face mesh (an alembic file in movement) and ropes made with single vert and whith cloths properties  parenting to my face (as child)
When my face moves, ropes move too but its dont collide to my face, they're just passing through this bloody face.
I have tried :
-set clothes "object collision".
-set my face mesh too rigid body / collision.
-duplicate my face mesh and puting at the same child level than my ropes too see if ropes can't react to its parent.
Is that doesnt work because my ropes (clothes properties) is children of my face mesh ?

Thank you :)

I think your problem has to do with the fact that the meshes of your cable objects consist of edges and vertices only. I believe for Physics to work between an object with Collision and an Cloth Object, the Cloth object needs to have faces. Otherwise it will not interact with Collision objects.
Also: Visible geometry created by a Skin modifier is in this regard cosmetic only. Even if an object with faces has an Skin modifier, the geometry created by the modifiers also does not interact with Collision objects.
Here is also an image to clarify:

Selected on this image is a cloth plane with zero thickness, that fell onto a larger collision plane, and then stopped moving. The thickness made by the Skin modifier clips trough the collision plane, and was not directly influenced by physics.
Under it is the same cloth object, but with all the faces removed (so vertices and edges only). If fell right though the collision plane.
Next to it is a similar cloth object but the mesh is a single vertex (it looks like a cube). It did not move or fall at all.
(On a related note: If a Cloth object has faces but still moves through a Collision object, it might help to move the Cloth object, or alter it, so its geometry won't clip (or stick through) the Collision object, since that can cause further clipping or other undesired physics results.)


Is it possible to paint an object inside with one texture and outside with another? I have a tooth model. I want it to be white outside and (any) voronoi texture inside.
Is it possible?

tooth model

tooth model with materials

How to ger rid of those red things? They're caused by boolean modifier

So, as your question is equivocal, you have 2 possible situations: Either you're talking about an object that is open and you need to give 2 different materials to each side of the same face OR you're talking about the intersection of an object with its boolean object.

Option 1: For an open mesh, use the Geometry > Backfacing node as you explain. Mix it in a Mix shader to separate 2 different shaders.

Option 2, if you're talking about the face that is the intersection between your tooth and the object you'll use as boolean, you need to give your boolean object the material you want to see, and make sure that your tooth has both its natural material + the same material as its boolean object. Here, both the cube and the tooth have the orange material:


is there a quick way to delete a group and leave the objects? I added my objects into groups to append them easily and now I have got bunch of groups which I don't need anymore. how can I delete them?

Ctrl-Alt-G opens the remove from group popup where you can remove all selected objects from all groups. When the last member of a group is removed the group itself will be dissolved.


Cut big mesh (plane) in quadratic parts I am working on a game-engine and the time has come to model a simple map. I thought, since i already use blender for models, why not for the map, since creating a world-editor can be time-consuming. The problem is, my engine expects the world to be in quadratic chunks of equal size. I'd like to model the map as a big plane with structures on-top in Blender and afterwards, cut the whole scene with plane and structures in equal quads to export them individually. Is this possible?

Example:

I'd need the whole terrain-plane to get split at the red lines and the little house, so every part of the house is in the corresponding chunk when i export the chunks.

Alternatively, when i create multiple equal-sized quadratic planes, to somehow glue one edge of one plane to another edge of another plane, so i neither get holes in between, nor get overlapping faces?

To do this first join all your objects into one if they aren't already by selecting them all and hitting Ctrl+J.  Then create another grid object consisting of just edges which you will use to slice up the map.

Select the grid and then the terrain (in that order), enter edit mode, go to top view (numpad 7), make sure you are in orthographic mode (numpad 5 to toggle), then use the knife project tool found in the toolbar.  Make sure cut through is checked after you do so.

Your terrain will then be sliced up based on the grid object's edges.


Purge unused data (e.g. particle system, or groups) by script How can I completely remove a objects (e.g. particle system or groups used in particle systems) in blender using python?

The problem is this: I have a script, with which I create a scene (e.g. adding some normal objects and some group of objects with a particle system). For a research study I would like to repeat that that several times, without restarting blender. So I can create a scene, delete everything, e.g. with a script like this:

import bpy
scn = bpy.context.scene
for obj in scn.objects:
    obj.select = True
bpy.ops.object.delete()

If I rerun the script to recreate the scene with objects using particle system, the latter is not shown in the scene anymore (only the placeholders of the particle system). Now I'm not sure where exactly the problem lies, but I guess not everything is immediately deleted, running the script above. Only the startup of blender helps (but that's not what I want) or pushing the purge button. The purge button seems to start the command:

bpy.ops.outliner.orphans_purge()

But I can't get this piece of code to run in the console. It says that "the context is incorrect". Is there a way to purge the unused data by python script? Thanks a lot for any help.

To permanently delete curve data blocks that have no users  without reloading the project file (which can be bit problematic at times), you can use this python code:

import bpy
from bpy import data as D

for block in D.curves:
    if block.users == 0:
        D.curves.remove(block)

It'll iterate through all data blocks of type "Curve" and delete them if they have no users.


How to animate cvt belt as pulleys change size I was trying to make this cvt belt animation but can't figure it out how to make increase or decrease belt size animation I have tried curves but doesn't work.
Any body can recommend how I can I do a belt animation like this

The changes in a CVT belt ratio can be simulated using softbodies in Blender.

Details

Create a new blend file.
Add geometry for the pulleys and belt as shown in the animation.
Set the pulleys physics to act as collision.
Set the belt as a softbody.
Turn off gravity to prevent the belt from slipping.

It take 2 steps to animate the belt size change. First the belt needs to be fit to the pulleys. Then the pulley size can be animated with the belt keeping fit.

Animate the pulleys moving apart to the final location. The belt will stretch to fit the pulleys as they pull apart.
Animate the change in pulley size. The tension on the belt will ensure it stays close the pulleys as they change size.

The blend file is available here -


Blender 2.8 won't let me import reference images I have returned to blender after 6-7 months of not using it, and wow has it gone through some changes. I've been re-teaching myself this program, and have ran into a problem that people online can't answer, as it refers to earlier versions.

My problem is that I can't import reference images. I've tried using the import buttons, I've tried searching the program for background/reference image importing options, and even trying to just drag it in. Nothing is working. Does anyone know a solution to this problem?

Thanks!

Welcome back to Blender

You import reference images by "adding" an Image, pressing Shift+A and selecting the subcategory "Image"->"Reference".

A "File Browser" window will open where you select the image.
After you selected the image and confirm it, the image will appear in the viewport.
Further settings can be accessed by going in the "Object Data Properties".

By the way, dragging an image into the viewport works as well.
But i don't know where you tried to drag it to.

Happy Blending


Is it possible to cause an object in Blender v. 2.79b to produce a sound whenever it is struck? While creating a 3d model of a guitar, I have been trying to figure out how to make the strings vibrate and produce a sound when struck.  I am not sure what to do to get it to work.  I have looked online several times for tutorials on how I might get this to work, but without success.  Can you help me?  NOTE: I know how you can add audio through the Movie Clip Editor.  This is not what I am looking for.

P.S. I request that the community tag this item with any other relevant tags.

Yes, you can use a cylinder as a string and shape keys to move it up and down:

Create a new Shape Key to move up and down the string:

Then move the string up with Proportional Editing turned on:

Allow the shape key to get a minimum value of -1 to let the string move down:

Then animate the scale of the object:

Bake the sound file to the onto the scale animation curve:

Next bake the animation curve:

Copy the keyframes from the scale animation to the shape key animation:

Delete the scale, location and rotation keyframes (don't forget to set the scale back to 1.0 in all axes after this):

Finally, add some noise modifier to the animation curve to move the string up and down:


How can I have Screencast display keys pressed during transform operations? I'd like for the Screencast to display keys that are pressed after a transformation is begun. For example, after I select this cube and press S to scale, I then press Z 3, but neither the Z nor the 3 are displayed:

How can I get these keys to show?

Scaling is a modal operation itself, just like the screencast keys. During the transformation, all events are consumed by that modal operator and never occur for the screencast keys addon. There is no controllable event bubbling like in browsers.

It could only be solved by a native screencast keys implementation through which all events would have to pass first.


How to round circle inside UV I don't really know how to explain it, but the image is self-explanatory. Feel free to ask for more details if needed

Check your view axis, you need to look at the face you need to unwrap. Maybe change to ortho to go 100%. Select the faces for the eyes, go to UV or press U for unwrap methods, select Project from view and check the scale to bounds.


Smoke+fire wispy and transparent in render, but fine in render preview My .blend file can be found here.

When I view the simulation in the viewport, it looks normal, like this:

When I view it in the render preview with SHIFT+Z viewport, it looks perfect:

But when I render with F12, it's strangely transparent and looks odd!:

Here's my node setup:

Also, try viewing the images on imgur directly. It's more apparent what the problem is.

Ignore the funky flow shape. Thanks in advance.

Unfortunately, (as mentioned in the linked thread), this issue is a bug.

There is a workaround however, which isn't ideal or 100% polished, but its a quick and dirty method to get the job done.

1. As you can see in the screenshot, I have the same issue (Note: This bug only applies to the 'Fire' flow type, the 'Fire & Smoke' type renders without issues).

2. Begin by ensuring that Transparent is checked under Film in the Render Properties Panel, and also that the PNG Type is set to RGBA in Output.

3. Next add a large plane behind the fire object. Ensure that it is wider than the bounds of the camera and is far enough back from the fire object as not to cast light onto it. Give it a simple deep blue emission shader, with strength set to 1. (Note: I've noticed a bug here in 2.74 whereby if there is an object behind the viewport display of the smoke and fire, it wont dispay properly. Don't worry though, this doesn't seem to affect the renders.)

4. Render the image and jump on into the Compositing Screen Layout. Check the Use Nodes, Free Unused, and Backdrop boxes below the Node Editor, and add in a Viewer node.

5. Hit Shift+A and go Matte>Keying, add this to the Node tree.

6. In the Key Colour setting, use the Eye Dropper tool to sample the blue from the original render, this will mask out all hues from the render which display the selected colour. If the blue appears black, it's likely that you don't have the Use Alpha check-box ticked on the Viewer and Composite nodes.

7. This should update the render automatically in the bottom left Image Editor. If it has simply hover over the transparent render and hit F3. If not just give it another render, ensuring that the Compositing check-box is ticked under the Post Processing tab in the Render Properties Panel, and it should display the composite fine.

Et Voila, the final render! :) As I mentioned it's not a perfect solution, and where the blue was subtracted from the edge of the flame it has become slightly pink tinted, but for all intensive purposes it works okay, and colour correction could be applied either in Blender or in Photoshop/Gimp. Finger's crossed the bugs'll be fixed in the next release.


How to remove mirrored weight painting only? At some point I achieved it with the foot (image 1). Now I cannot seem to remember how I did this; I cannot find where the option is to turn off the mirroring for weight painting only and continue to have the geometry mirrored and not yet applied (image 2).
Thanks in advance.

I looked at my vertex groups and I at one point must have made a right foot variant before I had removed the bones from the right side. I will remove the right vertex groups, symmetrize the bones, then go from here: How can I mirror weight painting?
Unless there is an easier solution that is posted.


Disappearing wireframe after clicking on green triagle 2.8+ Today I've faced some kind of strange behaviour from blender 2.8.

I was working in Viewport Shading mode with x-ray off and geometry>wireframe off. Probably I had activated something because now after clicking on a green triangle in the scene collection window my wireframe completely disappears. The worst is that this behaviour persists absolutely everywhere. In whichever model I open that green triangle now removes wireframe and ever after restarting.

How to turn it off?!

That is original plane 1 with Object property> Viewport display > Wireframe unchecked however it exists.

Apparently these wireframes were created after importing models to old blender and then copying to 2.8+.

Probably it is a bug since I can't reproduce that effect on new models.


How do i get rid of wrinkles in a subsurf I have been modeling a dagger. I've just finished doing the rough profiling. I've added a subsurf modifier to smooth it out a bit but i cannot figure out how to get rid of these wrinkles. can any of you guys help me out? Thanks in advance.

Here's the Blend File: https://www.dropbox.com/s/b6u1lf41x9vujwd/Dagger.blend?dl=0

I'm not sure if this is what you mean, but if your goal is to selectively convert some of the smooth transitions to sharp transitions, you can do this either by adding additional Geometry (often through loop cuts, as shown here):

(note: sharpness depends on how close the new loop cut is to the old loop cut, because the subdivision surface adds geometry between them -- hence, if there is no or little space between them, the subdivision surface has little or nothing to smooth)

Which results in:

And/or by using Mark Seam: Sharp

(result not pictured)

If, instead, you want to remove some of the undesired unevenness of the mesh or something else, a different answer/solution will be needed.


UV Unwrap - Object - Select Faces ONLY - and Paint UV I have two part problem.

First:

I have a circle object, you can see the UV in black.
I selected the middle faces as you can see. I UV unwrapped on the selection.
I am paining those faces(selection), as you can see in the UV editor to the right of image.
BUT! There is the same painting over and over in each face on the entire object? That is an unwanted result.
I only want to paint on the selection in the UV editor. Is it a node setup I did wrong? I can't seem to find this particular circumstance.

Second:

Where are the paints? In the center I have stroke and fill, but they don't seem to do anything. No matter what color I choose, it only paints that white-wash/gray color.

I added this image below (edit): Seems I got the correct Tool-box open. I can paint.

1) You started with a resetted UV mesh (all faces overlapping and occupying all UV space available), then you re-unwrapped part of the mesh. The two unwrapping operation got some overlapping, you can see it if you select all faces. The correct way is to unwrap one time only, then select the faces you want to paint, turn the 3D window into "texture paint" mode, enable the button named "face selection masking for painting" and paint in the 3D window.

2) The stroke/fill controls you tried to use are referred to the grease pencil only. In the UV/image window, you can acces to the paint controls pressing T, to show all tools tabs on the left of the window.


How can I increase the thickness of this object without breaking it? I'm attempting prepare this object for 3D printing in VeroClear resin. The two halves of the icospheres have been solidified and have a default thickness of 10mil. The objects themselves are scaled to be about 9" on the x- or z-axis. However, I'm aiming for a higher thickness (100mil). When I increase the thickness value in the solidify modifier, the model breaks.

File link: Star Blender File in Google Drive

Objects with a default thickness in solidify modifier:

Objects with thickness updated to 100mil:

Relatively new to Blender and modeling for 3D printing, so I'd really appreciate any suggestions on how to proceed. Thanks!

I'm not 100% sure if this would work, but you might try it (quite possibly with the solidify modifier off, or perhaps only turned off after step 3.) and see if it does:

In Edit Mode, select all vertices of an object.
Extrude, but don't move the extrusion. Simply click to finalize. This will create
duplicate vertices, which in this case, you actually want. Duplicating the selection might also work.
Lastly, scale up. Only the duplicate vertices should be selected after the extrusion
operation, so scaling will move them out and create a "shell" of
sorts.
Then add or remove geometry as needed to fill in gaps this
process might create.

Not gonna lie, if this works it's a bit of a messy solution. Make sure you have a backup save so that if you don't like the results you can revert back.


Emulate non-number numpad keys? On my tablet I don't have a numpad, so I have enabled Emulate Numpad in the user preferences.  This allows the normal keyboard numbers to perform the functions their respective numpad number buttons would normally do.

However, this only emulates the numpad numbers, not the other buttons it has such as . (center view on selected) or / (local view).  Is there any way I can emulate these (and all the other numpad keys) if I don't have a numpad?

As mentioned the \ is already set for local view, the = (+ without shift) and - are also set to replace the numpad +/- (for zoom in/out). For others you most likely want to setup some custom keys.

In the Input preferences you can search for key-bindings containing numpad and then adjust the ones you want to use by clicking the key display and choosing another key. The issue is finding a key that isn't used or that you don't make use of, then save your settings so they are always available.

You may find that the [ or ] can be used as they are shortcuts to brush size when sculpting/painting where F is more well known. Also 2,4,6,8 and 9 are less used by many people.


Rigging character, mesh not following bones I'm following this tutorial trying to rig my character https://www.youtube.com/watch?v=qDlJx3J5HX0&ab_channel=KeelanJon but when I switch to pose mode the mesh won't follow the rig when I try to rotate or move it (I have parented the mesh with the rig using automatic weights). It's my first time rigging an character and I don't know what I'm doing wrong.
Thank you!
https://drive.google.com/file/d/1Yh7wemHduiglJRc_UBuAtwaXgKNjEolV/view?usp=sharing

It looks like your ears are very dense and make the parenting fail, so you should simplify them. More genarally your whole mesh is way too dense, especially ears, eyes and hands. You should avoid that, high-poly meshes make any edit and animation very tedious, and if you use a Subdivision Surface modifier it makes it even more useless. So rework your mesh before parenting.
Also you have 2 Subdivision Surface modifiers, keep one only, give it a level of 2 but disable it until you have a good mesh.
And don't forget to apply the scale of the armature and mesh.


How do I fix flickering in rendered view mode? I am new to blender. I am trying to create a donut but when I use rendered view mode there is a lot of flickering on the donut. In fact, it does not look much like a donut at all anymore. How do I fix it?
donut in solid view mode:

donut in render view mode:

I restarted blender and updated my graphic drivers. There is still some flickering but it is somewhat better.
donut in solid view mode:

donut in render view mode:

That is because you use to few samples. As you increase the samples count in the render properties, below sampling, your image will get smoother. Also, it is a good idea to turn on denoising  in the layer properties all the way at the bottom. Now just press f12 to enjoy your render :)
Hope this helps


How to change a flat section of a mesh into a smooth curved one I have this mesh:

It's crossed shape; what I want is to turn the inner flat sections into smooth curved ones (white marks showing what I mean).
How can I do this?

From a similar model you already have, you can use "smooth vertex":


How can I combine two separate object? I seperated the one cylinder to two parts for texturing

(The reason why is it separated, ı don't have idea "how can ı different texturing on the one part?")

Now,I want combine the different two parts like in the beginning(like one cylinder)

Thank you for helps :)

First, select both objects, and press Ctrl+J. Then, go into Edit Mode, select the both rings of vertices on the ends of the gap, press W and then select Bridge Edge Loops.

In order to have different texturing for different parts, you'll need to make the different textures into different materials, (so if you want two textures, you'll make two textures,) and then, select vertices you want the material to be put on, select the material you want to put on them, and press the Assign button, which is under the material name.

Read: Add different materials to different parts of a mesh? (frequently asked question)


Trying to create a 3D print of a spray paint stencil and I'm having difficulty joining 'islands'. What I'm doing wrong? I'm trying to create a spray paint stencil in blender and then 3D print it so I can use it for spray painting. I'm having difficulties joining the 'islands' to the rest of the stencil. For example, in the following screenshot, I'm trying to join the hole in 'd' and 'o' with the rest of the stencil

What I have done is the following:

Create a text object, change its font, text, etc.
convert text to a mesh (Alt-C).
create another object (I've tried planes and cubes) which I'll refer to as the 'stencil', and make it 10cm x 4cm x 3mm
Apply a solidify modifier of 1mm to 2mm
Apply a difference Boolean modifier on the stencil with the text mesh

What I attempted afterwards was to go to wireframe mode and join the faces together, but I had to subdivide several of the faces.  What happened afterwards was that I keep getting manifold edge errors from the faces I created and when I attempted to dissolve the edges, it ended up deleting a vast majority of the stencil's face.

I've also tried doing a bridge edge loops, but because of the curve natures, what I ended up with is this mess and 28 bad contig edges error.

Clearly whatever I have in mind isn't working out too well. Does anybody have an idea on how to make this work?

I think the normals on the inside of your main character profiles are flipped .. it would explain the twisting on the bridge. Also remember, to be tidy, Bridge Edge Loops needs an equal number of vertices on both sides.

Try a quick CtrlN 'Make Normals Consistent' on the entire mesh in edit mode.

Have a look to see: in Edit Mode, Properties Region > Mesh Display panel > Normals > Face..

It would probably be easier to create the bridges in the flat, before extruding the thickness of the piece.. you could, instead of using a Boolean, Knife-Project the text down on to a plane, make the bridges, and then extrude.


Keep getting duplicate circle Hi I am new to Blender and I am trying to select a vertex that i can then drag down on a uv mesh sphere. However I keep getting a duplicate circle. I am so frustrated bc I do not understand why this is the case when I right click and click the vertex.

I thought it may be easier if you saw a video so go to this link ... if this is not what you wanted let me know.

https://youtu.be/C31vVLQxWME


Navigate the disk cycle, like you can navigate the loop and radial loop cycles in bmesh? So, in bmesh you can navigate the loop cycle via

loop.link_loop_next
loop.link_loop_prev

You can navigate the radial loop cycle via

loop.link_loop_radial_next
loop.link_loop_radial_prev

What I'm missing is access to the disk cycle. There should IMO be

loop.link_loop_disk_next
loop.link_loop_disk_prev

which would allow you to cycle the loops around a vert, as described here.

Is this something that's coming in the future? Was it left out deliberately? If so, why?

I realize you can do it by combining the loop and radial cycles, but it's not very convenient.

Any input is appreciated!

Something like this?

[edge for edge in vertex.link_edges]

Where vertex is bm.verts[n]. I assume it's in order, otherwise I have to fix my code too if it isn't.

If you want loops, there's also link_loops.

edit: Here's the current way I'm doing it that actually works ok (radially sorted 1-ring of edges for a vert)

def radial_edges(iv):
    loop = iv.link_loops[0]
    eg = []
    while True:
        eg.append(loop.edge)
        loop = loop.link_loop_radial_next.link_loop_next
        if loop.edge == eg[0]:
            break
    return eg


How do I lengthen a cylinder that is tipped on it's axis? I need to lengthen objects that are tipped on their axis. I have tried to use local transform orientation and it doesn't work.

You can always move a face along its normal by using the 'Normal' transform orientation.
If combined with the 'Individual Origins' pivot point, many face-islands can be GZ moved along their normals simultaneously:

(This is not scaling.. any selection of top or bottom faces could be moved just as easily.)


What is the difference between "Generated" and "Normal" texture coordinates? I cannot understand from the documentation the difference in the Texture Coordinate node (in Shader) between Generated and Normal, and even the purpose of the Texture Coordinate node itself, which I have as the first node.

It may help to visualize it this way:
When we render a scene, for each pixel on the camera we project a ray, and if we make contact with the surface of an object, we ask "What is the color that should be reported for this pixel given material properties, lighting, occlusion etc?"

This is fairly simple when the material is a solid color, but what about materials that vary?
A procedural material can be thought of as a "field" in the physics sense, it exists and has a value in every position in your scene.  When you map this texture to an object and look at it in the viewport you are displaying the cross section of this field that coincides with the surface of your object.

The Texture Coordinate node merely defines the X,Y,Z coordinate space used to map the texture.  Object coordinates, for example, use Blender's scale setting and set the object's origin as 0,0,0.  Generated coordinates use the object's bounding box as the coordinate space over a range of 0,0,0 to 1,1,1.

Normal coordinates are a little strange.  My current understanding is that they are less based on position, and more on the rotation of each individual face (more specifically the normal direction).  Maybe someone will expand on how this may be useful for you, my knowledge is limited on this one.


How would I add dots to the texture on a 3d object? I am pretty new to blender and I've been trying for a little while to get dots on a 3d surface.

On the picture below you can probably better see what I am after. On the top is the image I am trying to recreate, and I am wondering how I can get that dot pattern onto my model. My model does have a bool and subdivision modifier, and I feel like that is making it a bit harder. I have tried following this (Procedural polka dot pattern with cycles), but I cannot get it to work on my model. I've also tried texturing, but I don't know how that works too well and the dots just get stretched out.

Does anyone have any suggestions?

I like your way of thinking, but the procedural texture you picked is meant to be used on a 2-dimensional plane. The z-scale isn't being touched at all by the other nodes.

While i cannot give you a setup for a procedural texure, why not create a small .jpg or .png and then scale up the UV map? You may have to mark the seams manually to get it lined up perfectly though. If you're using Smart UV, make sure "Stretch to UV Bounds" is deselected to not mess up the aspect ratio.


Identify Vertices intersecting with Bounding Box using Animation Nodes Within Animation Nodes I have (a) the bounding box of an object I modeled and (b) random vertices from the "Random Vector" node. The random vertices appear inside and outside of the bounding box.
How can I remove all vertices, that are inside of the bounding box using animation nodes? So that the random vertices only appear outside of the bounding box?
Thanks!

You can use Is Inside Volume node to know which vertices are inside the volume. Then use Mask List node to filter out vertices inside.


How can I put separate images together to create an animation on Blender? I am using blender and editing a youtube intro and I have every frame separately rendered on to a folder in my folder. Ive also rendered as xVid. How do I put the separate images together to create an animation? This is what I have.

Switch into Video Editing layout and focus on Video Sequence Editor.
Press Shift+A -> Image (or select Add -> Image from the menu bar).
Select all images you want to create the video from.
The video strip based on the image sequence will be automatically created.

Then you can of course render it to a regular video format.


Offset Camera to Local Axis I have a road with a plane locked to it through a curve and a constraint. I also have a camera that's locked to the plane with a Copy Rotation and a Copy Location constraint. However, when I enter the camera view, the camera goes inside the road, meaning I need to move it up. However, when I move it up (Z axis) and the camera approaches a bank turn, the camera goes way off the screen. So what I need to do is move it on the local Z axis. I've tried using the Limit Location constraint, but even when I set it to Local Space, I still have difficulties trying to get it to move on the local Z axis. Is there a way I can offset the camera so that it doesn't have this problem? Here's a picture representation:

Thanks in advance if you can help!
Here's the .blend file:

You can offset the origin of the plane using (for instance) the 3D cursor.  I placed the cursor above the plane and used Alt+Ctrl+shift+C then chose "Origin to 3D Cursor".  That means that the plane's origin is now above it, so the camera is now locked to the new origin through the constraint.


Why does a vertex not become part of the edge it was snapped to? I have tried for tinyCAD, Dynamic Space Bar, Intersect Tool and EdgeTools, Automerge and other stock options, but if I create a new vertex (Shift+D) and constrain it to an axis and I snap it on another edge, it does not merge together and become a lovely piece with that edge.
Besides, I have a small space to snap the Vertex near to Edge, but not on the edge. And I still couldn't figure out how I to merge the Vertex with the Edge afterwards.

But besides that I really like Blender so far and a lot of things are really well thought out and so I think it is me who is wrong.

To be able to merge this vertex with the edge you have to have another vertex as a part of the edge, to do so, select the edge and by pressing the W key subdivide it once then you can slide the vertex where you want by pressing ShiftV, and now you can merge this vertex with the other vertices.


Is subdivision surface modifier used only in blender? I have a question about subsurf mod in general. Do most 3d software typically use a subdivision surface modifier, or is the modifier more typical for blender?

This is a complicated question. The best general answer would be that yes, almost all 3D software has some sort of non-destructive subdivision function. It takes a lot of different forms though.

First of all, not all 3D software even has something that would be recognizable as a modifier stack. For example, in Maya, subdivision is an option on the shape node (equivalent to the object data block in Blender). Either via the "smooth mesh" function, or via render-engine specific settings.

The bit about renderer settings is probably worth mentioning, because subdivision is frequently applied by the renderer, rather than subdividing when building the mesh and handing the already subdivided geo to the render engine. By letting the renderer handle subdivision, you can export just the base mesh, which is generally faster since the renderer can optimize the subdivision while doing it's the other tessellating and pre-chewing that all renderers do when starting up. It also makes for smaller files when exporting the scene to disk since the scene file will store the base mesh and a subdivision flag rather than the subdivided mesh.

The "micropoly displacement" feature in Cycles is actually an implementation of render-time subdivision, among other things. (such as view-dependent subdiv, displacement of the subdivided mesh, auto-bump). When a subdivision modifier is at the bottom of the modifier stack and you check the "adaptive" checkbox on the modifier, the subdivision modifier will be skipped on export and Cycles will be given the base mesh with subdiv settings in its place. Cycles will then generate the subdivided mesh on the fly at startup. There's no reason this couldn't work with non-adaptive subdivision as well, but AFAIK it doesn't do this as of 2.79.

Something similar happens when exporting an Alembic cache and you check the "use subdivision schema" flag. The modifier will be skipped, and a flag will be left in the file that tells the importing app to apply whatever non-destructive subdiv function it has.


Applying opencv distortion parameters to camera or setting custom projection matrix for render I need to set a camera and render images with that camera. I have rotation and position data as extrinsic parameters and focal length, shift values and radial and tangential distortion coefficients as intrinsic parameters from opencv. I succesfully applied all the parameters except radial and tangential distortion coefficients.

There is an lens distortion value in Blender in Compositor Editor but it is just single value. I need three parameters k1, k2, k3 for radial distortion and two parameters p1, p2 for tangential distortion. How can I achive to use those parameters? I can manually set the projection matrix by myself. However is it possible to use custom projection matrix for each 3d points in the scene for render image?

The tangential distortion can not be modeled in the current version.

The radial distortion with three parameters can be entered in the Movie Clip Editor (Shift F2) in the 'Track' panel under 'Lens'. Then they can be applied with the Movie Distortion node in the Compositor (Shift F3).

The same question was asked by me here and also asked here. Check the answers to those questions for more details.

Regarding the projection matrix: 6 years ago, it was not possible to set a custom projection matrix, but a workaround using orthographic projection was suggested: see here. However, I don't know if this has changed since 2014.


How to render static and animated objects separately to save render time? I want to create an animation with 60 frames with two objects only one is moving. How to combine the rendered 60 frames of the moving object to
the only once needed rendered fixed object. In short : render only what is changing.

So.. You should use 'View Layers' (https://docs.blender.org/manual/en/latest/render/layers/layers.html).
As said above in the comments by @Bruno you should render the still as an image, on the other view layer render the animation with shadow catcher and in the video editor (VSE) add them together to a video.

(to be honest you can probably just render them separately and attach them together later in the VSE just as long as you keep original scene.)

I am attaching link to a demo scene, hope it helps. (https://drive.google.com/file/d/10fXBH4o2sz4b0ceBPyRouquxhjgi_8gZ/view?usp=sharing)


it is necessarty to fill this gap ? on eyeball? I am making a lowpoly character , and like to animate in couples of days, but I would like to know if I need to fill this limit ? this rings of the edge loops around the eye? consider this is the first loops of the eye or the final, depends how you can see it, I ve started to model over this area with few verts on it, however I am on the eye right now, see the picture, must leave it away? or fill the interior ?

see the whole picture.

If you're working low poly it would better to close it and colour it black. It would be different if you were going for max realism but at the moment I don't think it's necersarry. You may also find it easier yo UV unrap.


How to keep physics fast-moving objects from going through the ground plane? (not python or game) In physics, I am experiencing some faster-moving objects falling right through the floor. Most other objects land/bounce/etc. appropriately, but the fast-moving ones just fly right through the ground. How can I prevent this?

I solved my rigid body physics “falling through the floor plane” problem by raising: Scene > Rigid Body World > “Steps Per Second” and “Solver Iterations” above their default levels of 60 and 10. This scene has 10,000+ fast-moving cube objects. At default levels, over 100 objects fell through the floor plane. At 5 times the defaults, (300 and 50 respectively), only 3 objects fell through the floor. At 10 times the defaults (600 and 100), NOTHING fell through the floor. The calculation took longer, but was probably generally more accurate than with default Steps and Iterations levels.


Game Engine - Steering Behaviour Understanding I am working on a BGE Horror Game right now and I want the enemy to follow the player around, but not directly. I want it to also walk around radon parts of the map even when the player is not there. Is this any possible with the Steering Actuator? And also, I have seen the different behaviours that I can apply (Path following, Seek, Flee). What is the difference between these 3?

Thanks in advance!

Possible result:

What you're searching for is called a "Navmesh" and it is done without any python-code.

Therefore you need the Steering-Actuator.

The Seek-Mode makes your object to allways face into the direction of the target and move towards it, until the set distance is reached.

The Flee-Mode is quite the opposite, it makes your object move away from the target, until the set distance is reached.

What you need for avoiding obstacles is the Path following-Mode. This mode uses a mesh that tells your object, where it can move and calculates the fastest way to the target.

1. Create a Navmesh - select every collision objects in your scene, including the floor. Then click on Build Navigation Mesh, which creates you a plane with holes, where your obstacles are. Play around with the Agent-Values if your scene has ramps or different hights...

2. Use the Navmesh by choosing your Navmesh as "Navigation Mesh" in your Steering-Actuator.


Method for creating a bulge in a fuselage What method would you suggest I use to create, as best I can describe it, the "bulge" or streamlined c-shape add-on found under some commercial aircraft (see the underside of an Airbus A320, or a Citation Latitude as examples)

I have the fuselage (cylinder) modeled, and am now stuck at how to go about adding this c-shaped bulge under and attached to the the fuselage with its well-defined crease along the top where it meets the round-face of the tapering (to the rear) fuselage, and then its gets a streamlined shape at the bottom, front, and back. I have the aircraft's blueprints, so I know its size, location, dimensions, etc. but the method for adding this is my stumbling block for now.

I've added a couple of images to show what the end result should look like, so hope that helps.

What's the best method and tools you'd suggest I use in Blender to get this done?
(I have both v2.7 and the 2.8 beta -- so can use suggestions for either version)

Thanks for the help!

Hard to do it without a complete blueprint, but I guess you can do it this way:

Create the right view profile, which is basically an extruded cylinder.
Draw the wing cut with the knife.
Extrude the wing, use all the views to make it correctly.


How can I animate an interior scene from day to night? I have a basic isometric interior room and I want to animate how this room looks when the sun goes down and it becomes dark, day to night.

Something like these videos, 01, 02

So I'm wondering how to animate skytexture and sun to look like that, or if there's another way.

Thanks

If you are using Cycles or Eevee

Light your scene with:

a world node setup using a Mix node between two Environment textures:

a nightlight texture like this
a not too bright daylight texture without a visible sun direction (highly overcast) like this, because you will like to add and animate the Sun yourself

a sun lamp with some "midday" inclination, parented to an Empty that stays at ground level in the middle of the scene (you could also put the sun lamp directly in the middle, but with an Empty it "looks" nicer while you work on it).
indoor lights

Animate by setting these keyframes:

Starting frame:

the Empty is rotated such that the sun is high in the sky.
The sun Energy is high. The sun color can be slightly orange if the daylight world texture is slightly blue
The world Mix factor is at 1.0 (completely daylight)
no keyframes for indoor lights

at ~80% of the transition

indoor lights Energy is zero
no keyframes for world/sun

at ~80% of the transition + a few frames

indoor lights Energy is high
no keyframes for world/sun

Last frame:

The Empty is rotated along either the X or the Y axis in a way such that the sun goes just slightly below (and parallel to) the horizon
The sun Energy is zero. The sun color is neutral.
The world Mix factor is at 0.0
no keyframes for indoor lights


Simple Triangle Face Messed Up - Attaching to Weird Places? I'm not sure how to ask this so it makes it hard to search, but what is going on with this face? It's a simple triangle. I'm trying to add a face to 3 vertices and it goes completely wonky and doesn't fit in the vertices at all. It's doing this throughout the entire model no matter where I put my faces. What's going on? It kind of looks like it's attaching assumed edges to the centers of my edges where there aren't even vertices.

I had somehow accidentally applied a "Catmull-Clark" modifier to the object. Removing this modifier immediately resolved my issue.


Can i change the User an Action is associated with? After appending an action into a blend file, is it possible to associate the appended action with a specific user?

If I append actioned geometry or nodes, typically the action moves with them; but if I just append the action, then I will get the action datablock appended but without being linked to any object. How can I link the appended action to the required object on the stage (or somewhere else)?

Sorry it is a bit of an awkward question; I hope it is understandable. Let me know if you require any further information.

Sept

You link an action to an object not the other way around. You do this by selecting the object then choosing the action in the action editor.

While an action can be used by any number of objects, you can only have one action linked to an object at one time. To have an object use more than one action for an animation you use the NLA editor to mix the actions together.


How to simulate string? I want to make a group of party balloons. The strings on the balloons should have slack or be tight based on the length of the string and the location of the balloon. I thought the best way to start this would be to take a long thin cylinder and place it at the base of the balloon. How can I use physics to simulate this long thin cylinder as string?

Based upon this balloon tutorial:

Create a string
Create a bone as the "handle" (which you can then move around as you please)
Use the cloth simulator to simulate the string and use weight painting to select the part of the string you want to use.


Painting with weird noise I'm new regarding painting a model in Blender, I had some difficult with making a texture to paint, but when I did that, while painting this weird noise appears and I can't seem to find the solution.

What can I do?

Are you using a texture or a brush mask texture? That could be what is happening, but can't see the rest of your settings for the brush.


How can I rig a multiple-axis robot? Is it possible to create a animation of multiple axis motion or robot?

The key point of my question is kinematics. For example, when the end of a SCARA robot performs a straight line in 3D world, each joints rotates at different but specific speed at specific position. Is it possible to be carried out by Blender?

Is there any Blender function that supports the above movement? Or if Blender accepts third party coordinates, such as text file of pre-calculated axis angles from Matlab?

Is there any Blender function that supports the above movement?

You are looking for solving the motion with Inverse Kinematics, in fact exactly like an industrial robot solves joint trajectories needed for the robot to guide some tool along some trajectory.

Here is the documentation.

You put IK constraint(s) on last bone of bone chain(s) you want to control to comply with some given position/motion given by another object or bone (the target for the solver).

For every bone of this chain you can also limit the degrees of motion for each joint. The settings are under Bone tab in Properties panel.


How to rotate object on axis (planet)? Ok Im not sure whether this has been addressed specifically but I have some planet orbit rings that I need to rotate ON the axis, meaning they stay at an angle but rotate -

so far Ive parented the ring to an empty and am just rotating the empty which results in this (NOT good):

The tilt should always be more/less like #1 - how can I do this?

To achieve this particular rotation, you need to change the transformation orientation from global to local

Then if you press R to rotate and then Z twice, you will rotate the object on its local Z-axis. You don't have to have changed the transformation orientation to achieve this, it just help visualise the axis you're going to use

Hope this helps.


How do I make my camera render more of the scene? When I go to render an image of my scene it only captures whats in the outlined area box. what I want is to capture what I see in the scene.

example picture below , I want to capture the ring and the monkey in the scene.

You can clearly see that once it renders the image its going to show the cube and parts of the ring and monkey.
I do not want to have to reposition all of my objects.

You can move the camera in the scene until the desired position is achieved.

To do this, make sure the manipulation mode is set to local

This will change the manipulators to use the selected object's local axis.

Then, grab the camera's local Z axis and drag it to the desired position.

Or, while you are in the camera view, you can press G to move the selected object (make sure the camera is selected first) Then, press Z once to constrain the movement to the global Z axis, press Z again to constrain the movement to the local Z axis. then move the mouse up or down until you get the desired camera position.


How to apply textures without them mirroring? I have a person I modeled using the mirror modifier, and now whenever I apply a texture it mirrors the texture as well. How do I solve this?

If you've finished modelling can you just click apply to the mirror modifier which will then just give you a single mesh to work with?


Darker Object in Sculpt Mode The object i'd want to sculpt becomes darker only in Sculpt Mode and i can't interact with it. What can i do?
I was doing something with Subdivision Surface and after deleting the Modifier the problem started. I can't go back, I tried going Command+Z but nothing.

Have you tried to invert normals for the object? I had problems with darker objects when worked with materials, and there was a problem with normals.


Can a single F-curve be bound to several properties? When animating scale I'm having to juggle 3 F-curves. Which makes little sense for scale, as you would generally keep scale uniform.

So is there a way to animate several properties by one F-curve?

I would do this with drivers. I don't know if there's a way to make an infinite driver value range, but in this case, I just set it up to be 1000, which is far too big for blender to display the default cube.

Select the object in question (in this case, the default cube) and go to the object panel. Towards the bottom, you will see a section called "custom properties." Expand that and create a new property. I named mine "scales" to separate it from pre-made properties. You can set the upper and lower limit to however much you want. I used 0.0 and 1000.0 in mine. Make sure you make it a float, or else you will only be able to use whole numbers (a float is a decimal point, ie 1.0, 1.5, 1.0004, etc).

Create a driver on one of the scale axes (you only need one, which you can copy/paste to the rest). Right click on the channel value slider and create single driver.

Split off the viewport into a graph editor, then switch from F-curve display to Drivers display (the red box on the lower left). This will allow you to edit the driver and its data. Open the properties region, just as you would in the viewport. There, you'll see the drivers in their data form.

Now that the UI is set up, go back to the custom properties of your cube, right click on the value slider bar of the property you set up and copy data path (roughly half-way down the list).

In the driver setup in the graph, change the "type" to one of the options with "value" in it (ie minimum value, maximum value, sum values, average value). In the variable (the lower half of that driver setup area), change the default "transform channel" to "single property." Change the property type to the object (in my case, the default cube is an object, so i selected object), then find your object in the menu beside it (mine is "cube").

Remember that data you copied from your custom properties? Paste that into the "Path" field below. What it should change to is a small DNA-like symbol, which indicates your link is active. To be safe, click "update dependencies" at the top of the driver data area. Copy that driver to the rest of the channels and you'll be ready to go.

Slide the custom property around to test it. To animate the property, just key and edit the custom property just as you would a transform channel on a bone. It appears in the graph editor and since the driver interpolation is linear, eases are intuitive and very simple.


is there a way to select just the outer surface but not the inner? I've got some faces inside an object, but i want to delete them.
Is there a way to select all the outer surface without inner ?

You probably have got the nonmanifold elements there. Select the whole mesh in Edit Mode (A), go to Select-->NonMannifold, then delete the edges.

You may also use a MeshLint add on to do it. Activate it in User Preferences (Ctrl+Alt+U). Go to the MeshLint panel of the Data header, check the NonManifold Elements checkbox and click Select Lint button.


How to use Overlay layer in Grease Pencil to show drawing only over desired background to create blinking eye effect.

Here the basic typical setting -

we have three layers here,

set the top layer to ("blue square" in this example) Object data > layers> Blend = Overlay.
toggle the Clamp option for the layer below (in the layer rubric or next to the Opacity option)

you can see that the red circle is visible only on top of the green oval, but not on the blue background.
note that the red color changed, due to color mixing, you may adjust it.

Now I used this setting to set a blinkable eye:

I used the former setting, and -

I placed layers to not be effected, above the overly
I placed the 'pupil' layer under the overlay, but above the 'eye.white", and toggled the Clamp option.

Now when I scale the eye.white shape vertically, I get the blinking eye effect.
It can be animated too.
Note that now layers partly covered under the overlay (like 'neck') would not be covered as regularly, it is a bit of a problem, you may separate it into to two different objects.


How do I click to select more than one face a a time? I went into face select mode and it will not let me keep the faces as I select more and more. In other words, it only lets me select one face at a time. How can I make it so I can select multiple faces at a time and make the edit I need?

Just hold the Shift key while selecting, easy as that.


How to get a row of single-file particles? I'm trying to make a "crown"-like rim for a box, where the result should be similar to this picture:

The idea being that there are several triangle-meshes right next to each other in a row, without any overlap, and their direction is based on what part of the box they're on (x axis, face towards y, if on the y axis, face towards x), like the rim in the picture.

I tried doing this with the Hair Particle system (after making a mesh for the rim), and the result is like this:

First of all, the triangles are ot facing the appropraite direction, they're all facing the same way, only the ones on the x axis are faced the proper way, but the ones on the y axis should be turned 90 degrees. Also, I they're randomly spaced, I need them to be back to back with no space in between. Any ideas?

Instead of using particles, 4 array modifiers might be better.

Model one triangle, copy and rotate it 90° and give each one an Array Modifier.

Duplicate for the other sides. You can duplicate with ALTD instead of SHIFTD if you want to change the shape of your teeth later.


Water won't pass through channel, and how to make a rotor stay on its place while it spins? I am a Dutch engineering student, normally I use Inventor, solidworks or autocad to make 3D designs.

Now I have to make some sort of a water turbine and I gotta simulate the spinning of the rotor itself. Well, now I haven't used Blender yet, I just downloaded it and I am struggling with everything.

I want to make some sort of a channel to let the water flow through on the rotor. But it got blocked by some sort of an invisible wall and I don't know how to fix it or what I've done wrong...

Here's the link to a video, which makes it more clear.

Also I would like to know how to fixate a rotor and let it spin because of the water.

Please let me know how to fix this and what causes the problem. And how I can make the rotor work.

Here is the .blend file itself:

From just looking at the image without examining the file, it looks like you didn't make your water domain big enough. Is the water domain object covering the entire channel unit?


Is re-using materials on models faster than baking textures for each model? Say I have 10 models in the scene. They all have 3 materials on them (Red, white, and blue). I am using these same 3 materials over and over again on all of my models. Is my game going to run faster if I bake the textures of all of my models and make separate materials for each model, or if I continue to link the 3 materials on every model?

I'm using Blender Game Engine.

Even if Blender did something non-efficient, like making new shader for each object, there still would be an obvious benefit which @maddin45 mentioned. The less textures you have (the more you combine them in big atlases), the better.

As for the models themselves, think of modularity - make LEGO-like pieces and duplicate them.
http://blog.timothyeustace.com/2012/04/gears-of-war-wireframes.html


Blender mouse function is not working properly? I used the new mouse actuator and had it used for mouselook. It seems that you would need to turn an amount until the mouselook actually works. My threshold is set to 0, and I am very confused of why this still happens. I would like to have my mouselook start to move as soon as I move my mouse. How can I achieve this?

I also had this problem, and it can be fixed by simply lowering the sensitivity. Note that the reset distance is still smaller than the trigger distance, so this does not fix the problem completely, it only makes almost un-noticable and more bearable.

                     With problem                                                          Improved

The reason this happens is that the game engine, when calculating the mouse's movement, resets the mouse to the center of the screen slightly before it detects the new position.
If you do not move the mouse fast enough, the game engine resets the cursor to the center before it can detect it's movement.


Depth Pass to Pixel Projection (AN) Additional question to 3DSinghVFX's answer

To illustrate question - imagine this white/pink rectangles as rendered image of 6 x 3 pixels.
Here seen by Camera.

Animation Node tree (mentioned in the answer) generates a compact surface.

My question is ...
How can be pixels (reconstructed in 3D space from Depth Pass or Point Position Map as points) represented by unconnected quads orientated to Camera. To be seen by Camera as regular squares without gaps so final result is identical to original image.
In theory, since those faces aka pixels are oriented to camera they are still squares and from mentioned answer also grid is nicely even to a camera view ... So the only question here is probably how calculate size according to distance from camera.

Sidenote: Surface generated by mentioned answer is awesome, downside of that menthod are connections between front-back pixels that are empty space in real. Since there is not a way to store this kind of data in EXR, it seems to be better use pixels as separated to get similar result.

I'm also interested in version with coloured Points (spheres) scaled accordingly to Camera distance, to be seen by camera as same size.

I would appreciate if you can use the same EXR source data from original Q.
Thank you for help.

Method:

The idea is to first compute the distance from the camera for all vertices of a polygon 2) then find the vertex that minimum distance from the camera 3) then project the remaining vertices of the polygon accordingly.

Follow the Method for Depth Map with AN+EN to get this node-tree,

We compute the distance from the camera for all vertices of each polygon then reproject according to the vertex that has minimum distance from the camera. This will give a new polygon(s) that is perpendicular to the camera view,

Now, we have vertices for separated polygons and we can get polygon-indices and edge-indices with the help of the Separate Polygons node,

Blend File:

To add spheres at the center of newly project polygons, first, we have to compute the scale according to the polygon size like so,

Then use Extract Polygon Transforms node to get the polygon transformation and use the Step 4 scale for matrices to instance spheres at the polygons' center,

Blend File:


Problem: Linking empty to track places all empties at origin and won't move I have created a Scratch animation which was then recorded and tracked. The tracking is successful but I cannot reconstruct it in the 3D environment. Whenever I select one empty or multiple and try linking them to the track, the empties appear at the origin and don't move when I play the animation or scrub through. The tracks on the movie clip editor window move as they should along the track, but the empty in the 3D view window remains static.

It seems that a few minutes of fidgeting solved the problem. I turns out that it is required to have a camera on the 3D environment to properly link empties. That is all that I had to do, doesn't require much of an answer.


Imported OBJ Groups to Vertex Groups I have an OBJ file for a character, which I have divided into groups (left hand, right leg, etc).

I have imported it with separate objects for each group.  I can get rid of the seams and all the groups with the join command (Ctrl + J), but then there are no vertex groups. Which I need for rigging.  (I know there are other ways I can make vertex groups, just pretend I need them based on this OBJ file's groups.)

What is the fastest, most efficient way to convert all these separate objects into one object with vertex groups named with the separate object names?  is there a magic script/button for that?

You can write a script to create the groups with all the vertecies in one group for each mesh and then just join it.

I just quickly threw this together. I don't usually write much python, so don't confuse this with good code (I'm sure some list comprehensions could clean this up nicely).

import bpy;

selected = bpy.context.selected_objects
print(selected)
selected_meshes = []

# only use meshes of the selected objects
for obj in selected:
    if obj.type == 'MESH':
        selected_meshes.append(obj)

# for each mesh make a vertex group with all vertices in it
for obj in selected_meshes:
    vg = obj.vertex_groups.new(obj.name)
    verts = []
    for vt in obj.data.vertices:
        verts.append(vt.index)
    vg.add(verts,1.0,"ADD");

# join meshes
if len(selected_meshes) > 0:
    # copy selection to new context to avoid messing with selection of the current scene
    ctx = bpy.context.copy()
    ctx['active_object'] = selected_meshes[0]
    ctx['selected_objects'] = selected_meshes
    # this was jsut copypasta from here: https://blender.stackexchange.com/questions/13986/how-to-join-objects-with-python
    ctx['selected_editable_bases'] = [bpy.context.scene.object_bases[ob.name] for ob in selected_meshes]
    bpy.ops.object.join(ctx)


Separate 2D curve offset as new curve Is there away to save the offset of a 2D curve as a new curve? I've tried to achieve the same result with curve > transform > push/pull, but this didn't give the results I needed, because the offset wasn't constant. The geometry offset works perfect, but I really need it as a separate curve. Does anybody know a solution?

Enable shipped add-on Curve Tools. Sidebar > 'Outline' > Offset curve
Answer provided by: @Robin Betts


cycles - different effects when order switched, even with opposite factor I was trying to fade shadows out and found animated shadow fade on Blender StackExchange.

In the setup described above, shadow rays are multiplied by a factor, and that's applied to the factor on a Mix Shader that uses 0 for a Diffuse shader and 1 for a Transparent shader. You can animate the amount of shadow casting by animating the multiplication: 0 means cast shadows, and it fades up to 1, where it doesn't cast shadows. I duplicated that in a material that's normally blue, as in the screenshot below.

I found that counterintuitive, and wanted to switch the multiplication value so that 0 meant no shadows, and 1 meant regular full shadows. "No problem! Just swap the Mix Shader inputs so the Transparent is on top, and Diffuse is on bottom! Like the red material in the screenshot below.

That does eliminate the shadow at 0 and show it at 1, but the object is completely transparent. The screenshot below shows a scene with two cubes that would normally cast shadows to their LEFT. The left, blue cube is not casting shadows, with multiply of 1, as expected. The right, red cube casts faded shadows on an inverted factor, as desired, but is unexpectedly completely transparent.

Obviously my understanding is flawed. Can someone explain this effect to me?

Before giving you the solution, you need to understand somethings from Cycles..

When a ray from the camera is thrown to the scene, this ray will be tagged with 'is_camera_ray'!
As soon as the ray hits some object in the scene, a bunch of other rays are created, depending on the type of shader that object has (glossy rays, diffuse rays, etc).

Cycles first tries to check if the sample point on the hit object is illuminated by some light, so it throws a shadow ray directly to each light.

If this shadow ray hits another object before hitting the light, then you get a shadow of the second object in the first object.

The exception to this result is if the second object has a Transparent shader in it.

This will let the ray to continue its path to the light, and in return, the amount of light is multiplied by the transparent shader color.

This means that a transparent shader with a full white color will let all the incoming light to pass through the second object and the sample point in the first object will be fully illuminated.

Having a (0.5, 0.5, 0.5) color in the shader, will block half of the incoming light, and a transparent color of black, will block all the light in that path, which is the same behaviour of all other shaders.

Now, having a Transparent shader in the node_tree will also make it transparent to all other rays, inclusive the camera rays. To avoid this we make a switch from original material to a transparent shader only when the ray is shadow ray.

That's why we don't multiply the is a shadow ray by anything, as we want the transparent behaviour for shadows (1) and normal behaviour for everything else (0).

If you multiply the is shadow ray by 0.5, it just means that shadows rays will see 50% the top shader, and 50% the bottom shader, while all other rays will only see the top shader.

In this situation, any shadow ray will put a 1 in the is shadow ray output, which will make the Mix Shader node to output the Transparent shader instead of the Diffuse shader (which is the one visible to any other types of rays).

Since the Transparent shader has a color of white, the light will simply pass through and no shadow will be produced. Changing the transparent color will change the amount of light (and coloring it).

Solution:
Just animate the color of the Transparent shader.

read more in docs.blender.org