Save all images using names of materials I have an imported model I'm working with. The materials by default are named something like 054fF0_c. I usually rename all of these in blender to something that makes more sense. I would like to then 'Save all images' of the opened images in the UV editor window but I want them to have the names that I assigned in the material tab and not suggest the original name that's not my assignment. Is there a way to already accomplish this? I'm not a programmer by the way.

The following script should resave your images the way you want. Copy and paste this into blenders text editor and click Run Script.

If the same image is used by multiple materials, it will save a copy of the image for each material but only one will be used for all materials.

import bpy
import os

editor = bpy.context.screen.areas[1]
old_type = editor.type
editor.type = 'IMAGE_EDITOR'
override = bpy.context.copy()
override['area'] = editor

def rename_image(img, mat_name, img_count):
    editor.spaces.active.image = img
    fp = bpy.path.abspath(img.filepath)
    pardir = os.path.dirname(fp)
    sufx = fp.split('.')[-1]
    if img_count > 1:
        img_name = mat_name + '_' + str(img_count)
    else:
        img_name = mat_name
    img.name = img_name
    new_path = os.path.join(pardir, img_name + '.' + sufx)
    bpy.ops.image.save_as(override, filepath=new_path)

for mat in bpy.data.materials:
    mat_imgs = 0
    if mat.use_nodes:
        nt = mat.node_tree.nodes
        for n in nt:
            if n.type == 'TEX_IMAGE':
                mat_imgs += 1
                rename_image(n.image, mat.name, mat_imgs)
    else:
        for s in mat.texture_slots:
            if s is not None and s.texture.type == 'IMAGE':
                mat_imgs += 1
                rename_image(s.texture.image, mat.name, mat_imgs)

editor.type = old_type


Sound export in 44100 Hz instead of 48000 Hz, why? I started to use Blender as a solution for video editing, very powerful and agreeable. Nevertheless, I have a bug that I can't resolve. The sound of my  video is in 48kHz, my users preferences are also in 48kHz, but when I export in H264 the final editing, the sound goes out in 44kHz.

I also exported the sound only in wav, and same issue. Any idea where this issue comes from?

The sound frequency for the project is set here:

change it to 48000 Hz.


how can i change particle size by id of an already cached simulation? I imported several simulations i made in realflow and maya, because i found out that blenders wetmaps are extremely faster than other packages and i need to make a lot of them.

I'm completely new to blender but i can grab the hang of it quickly, already have everything setup, i just need to change each particle size randomly depending of their id, i'm thinking with python, in maya i already made similar things, yet i still haven't learned any commands for blender yet, can someone help me please?

Also, would it be possible to delete particles depending on their speed and/or age?

Everything is already cached from the other softwares and i'm just importing them to blender using the realflow addon.

i'm thinking something like this:

particleSystem="nameOfParticles"
particlesList=particleSystem[particles]
frames=xrange(1,100)
for f in frames:
    currentFrame(f)
    for part in particleList:
        randomSeed(part.id)
        setAttribute(part.size,rand(0,1))
        if (part.velocity>5) or (part.age>2):
            delete(part)

If you want to change the size of a particle randomly you can go to the physics tab in a particle system and change the random value.

If you want to look at the operators in python you can go to this link

Python blender reference

If you want to delete a particle based on their age you can change the lifetime of the particle in the emission tab


Control a ColorRamp node from outside a node group I have a ColorRamp node inside of a node group and I would like to have a group input which controls the "Pos" value of the white colour, but there doesn't seem to be a good way to do it. Since I'm only using two colours, is there a different way to do it?

You can use drivers on the Pos value.
All you need is a driving value.

Let's make the drivers from the group input. First enter the group node, select the Group Input node. In the sidebar (open with N). In the Node tab, you can add Inputs, name them and set their default/minimum/maximum values. I added two new inputs:

Get out of the node, right click one of the value inputs and hit Copy Data Path (here the White Posisiton):

Think of the Data Path is like the url of a website or the file path of a file on your computer, but here it's for any data on Blender.

Enter the group node, right click the Pos value corresponding to the data path you previously copied (here the white Pos) and hit Add Driver:

A pop-up will show to let you set your driver. Set it as I do:

Type: Sum Values
Icon next to "var": Single Property
Prop : Material → select your material
Path : paste the Data Path copied earlier
Hit the Update Dependencies button

Note that once your driver is done, you can edit it via right click → edit.
And you can also copy-paste it from one value to another.

So if you want to create one for the black handle:
- right click the white Pos value → copy driver
- select the black handle, right click the black Pos → paste driver
- exit the node group and copy the Data path from Black Position
- enter the node group, right click the black Pos → edit driver
- paste the new data path
- hit Update Dependencies

And here's the result:


Local/Global Scaling? I Have this line right in the cleavage of a character that I'm modeling, and I am using a mirror modifier to create her.

I was given a tip to reset the "middle" circle of vertices (The ones that are the closest to the mirror/Y Axis) by pressing "S" then "Y", "Zero" and then "Enter", but when I do this, it resets the entire action, because the "Local" "Zero" is where I started scaling from, whereas I want it to move to the "Global" "Zero".

Her chest

Shift + S
Cursor to Center (alternative to 1+2: Shift + C)
. to change to Pivot Cursor
Scale your thing


Mask Image Plane in Shader Editor or Compositor I have an image as plane imported in Blender 2.91:

Now I want to mask off the red wine and then animate it so it would fill the glas:

Yes, it must be solved in Blender.
Tried it in Compositor with Set Alpha node, but the size of the mask does not fit and the alpha is not correct. Not to mention that I can not figure out how to bring this into shader editor...

Any help very very welcome.
Edit:
lehuan5062 had the idea to solve it with a shader:
https://blenderartists.org/t/mask-roto-texture-of-image-plane/1278656/4
But still, animated masking in shader editor??

Boolean Modifier
Since you will have to separate lines of glass from red wine and white line on wine surface (that has to be part of animated section), seems to me easier to recreate pictogram in some vector app (so you can work with always sharp and clean shapes), import as SVG and animate with Boolean Modifier.

add the glass Solidify modifier to get thickness, it will prevent from z-fight, or bring this object a bit above
convert wine object (named Wine_Mask) to mesh and give it a Solidify modifier to get thickness (needed for later boolean operation)
add a Plane to use it as a wine, split face into two, upper part for white wine surface line, the rest as wine volume, add Solidify modifier with less thickness than Wine_Mask object
add Boolean Modifier > Intersect > Object - Wine_Mask

It can be animated in similar way as shader version too.

Shader
Shader controlled by Empty

keeps wine surface horizontal (independent on glass rotation)
volume controll
parented to glass keeps location

Roto-Mask
From what I know it's the worst way ever to do something like this. Mask's shape can be animated by simply pressing I in Image Editor, but in a very limited way. From UI point of view there is not any feedback that key framing is happening, so open Dope Sheet Editor to to see them. The biggest issue is that animated points of mask transit along shortest way from key to key (see this question). It isn't such a big problem to animate straight point movement, but curvy part would has to be animated frame by frame = time consuming.


artifacts on all my objects All my objects in all Layers have these kinds of artifacts, anyone know why that may be?, when i hit "P" to play blender game they dissapear, but its super enoying to work with when you are texturing and so on

Your End Clip value (in the middle right of your screenshot) is extremely high.

Computers have trouble calculating wide ranges of floating point (decimal) numbers with extreme precision and often end up with slightly inaccurate results. If you narrow down the range it has to calculate (by decreasing the End Clip), those artifacts will disappear.


How to change the handle_type of a keyframe I've just inserted? In the VSE, I create a new effect and a keyframe for a property (speed_factor):

scn = bpy.context.scene
sp = scn.sequence_editor.sequences.new_effect("speed",
        'SPEED', 7, start_frame, seq1 = s)
sp.speed_factor = 0
sp.keyframe_insert('speed_factor', frame = start_frame)

How do I then change the handle_type of the keyframe to VECTOR? It seems odd to me that keyframe_insert only returns a success flag rather than some kind of reference to the keyframe I've just created.

I figured out a way to do it but in my opinion it's not ideal:

keyframe = sp.id_data.animation_data.action.fcurves[-1].keyframe_points[-1]
keyframe.handle_left_type = 'VECTOR'
keyframe.handle_right_type = 'VECTOR'

It's not ideal because the action might have other fcurves but it solves my case because I know it doesn't for my particular problem.


UV Unwrap a "fragmented" mesh I have a mesh which is a collection of meshes with distinct geometry. It is the object on the left of the picture.

When I UV unwrap it, blender places the distinct meshes on a "grid" and "projects" those surfaces on the texture. The problem is that the meshe's parts are not in the correct position relative to eachother.

On the right object of the first picture, there is no partition on the mesh and the UV unwraps properly. How can I achieve the UV results of the object to the right for the object to the left?

Try project from view or place the uv islands manually to match the grid!
https://www.youtube.com/watch?v=Y7M-B6xnaEM
check this video for more info.


Python scripting failed I am having a "python script fail" on my project that I am working on and I do not know why. my script is programmed to turn on one lamp at a time and render an image with a different lamp turned on for each render.

import bpy, bgl, blf,sys
sceneKey = bpy.data.scenes.keys()[0]
filepath = "G:\rtitrial2"
# Loop all objects and try to find the Lamps
print ('Looping Lamps')
l=0
# first run through all of the lamps turning them off
for obj in bpy.data.objects:
    if ( obj.type =='LAMP'):
        obj.hide_render = True
        l = l + 1
print('You have hidden ' + str(l) + "lamps")

# now we can go through and
# individually turn them on
# and render out a picture
for obj in bpy.data.objects:
    if ( obj.type =='LAMP'):
        print (obj.name)
        obj.hide_render = False
        bpy.data.scenes[sceneKey].render.image_settings.file_format = 'JPEG'
        bpy.data.scenes[sceneKey].render.filepath = filepath + '//lamp_' +
str(obj.name)
        # Render Scene and store the scene
        bpy.ops.render.render( write_still=True )
        obj.hide_render = True

Instead of using bpy.data.scenes[sceneKey], just use bpy.context.scene to access the current scene. You also don't need the parentheses around conditions (it's Python, not C or Java). More important is the string assigned to filepath, though. \r means "carriage return". Just use forward slashes, Windows can handle those too.

Alternatively you can use \\r.


where is X-axis mirror in 2.8 blender i found amature-global x mirror in edit-mode. but it is not X-axis mirror.
where is it?

Now you've got all sorts of mirrors in the top panel

upd: I was a little bit too hurry and didn't check if mirror options for mesh edit mode are the same for armature edit mode, but x-axis mirror is still there for armature. And it works as a mirror i.e. I move left wrist and right wrist is moved symmetrically. I've added another pic. You should have the same panel in armature edit mode unless you have manually edited your default UI.


Change video start when 3d tracking I made an animated a model in a blender that I will be putting into a video using 3d tracking.  The problem is that the video and animation are not synced up like I want them to; all I need to do is to, for example, start the video at frame -10, I don't want to cut the video so it is easier to work with and play around with the timing, and my animation uses some glitch(feature?) that only lasts from frame 1 to 100, so I can't move my animation. is there any way of changing when the video starts?

See Footage Settings in Movie Clip editor, N-Panel


NURBS convert to MESH and reverse operation I encoutered the same problem asked by @Travis here, and I applied the solution proposed by @Moog.
I tried thus to convert NURBS Sphere to MESH and delete Vertex, but when I tried to perform the reverse operation, I loose the object (see below).

Is there a solution for this ?
Thanks a lot in advance for your answer.

You cannot convert a surface to a curve without losing data AFAIK. I think you meant to convert to mesh.


What is the most effective technique for modeling? I've been using subdivision on a cube when I model, but the problem I have with this technique is that I'm restricted to only working with the amount of faces that the subdivided cube has.
Is there a more effective way to create more complex models or do I just need to practice more?

To define what is the most effective 3d modeling technic, all the know technics should be evaluated in several factors, such as:

Time demanded
Computational cost
Quality
Practicality

And be considered for all different artists, computer configurations, type of scenarios, and even consider if the technic can be incorporated in a production pipeline among other artists. So, it is impossible to answer your question accurately.
BUT
To help you discover more about the various techniques (or styles) to do a 3D model in a DCC software such as Blender. I would suggest you watch this video from Gleb Alexandrov as a good start.

Is there a more effective way to create more complex models or do I just need to practice more?

Also, as referred to in other comments, the modeling technic depends on what you are modeling, so maybe there is a better way to modeling, maybe not. But it is very common that along the process you discover ways to speed up or improve your knowledge to do 3D models.
And about practice, I guess the only person who can answer that is your employer or your clients. Because even if you have been modeling for 10 years, there are always new technics that you actually never practice. So it depends a lot on your expectations and demands.
Do your best, enjoy the process and stay curious.


What is the easiest way to have a default "Good" lighting setup for cycles? Can I have a not too dark scene in Cycles at Startup?
Because I'm not so good at lighting. Two I don't want to mess with it every time. Three I want to have a Quick Way of seeing how my model looks in Cycles.
The lighting Setup at start is great in programs like Keyshot and Marmoset Toolbag; you can load every model in it and it will look good from the start.

I usually keep some generic lights on a hidden layer in my default .blend, so I can just enable that layer to get an instant light setup.

To do this:

Open a new file (⎈ CtrlN)
Create your light setup:

Here are some good tips on lighting.

There are also some nice light setups in the community if you don't want to make your own.
Move the lights to another layer (M), then save the startup .blend (⎈ CtrlU).

This will save the current file as how blender will start up by default, so make sure everything is how you want it (visible layers, selected objects, view orientation, etc.)

Another thing you can do is use HDR/environment lighting.

You could try this addon, or use HDR panoramas such as these as environment textures.

To do this, add a HDR environment texture to the world surface (1) and (2) (it doesn't matter whether you add it in the node editor or the properties editor). There are no lamps in the image below:

Also remember to enable Multiple importance sample (3) when using environment textures, otherwise you will probably get a lot of noise.


How to make windows into a wall? I want to know how to cut a cube and delete some parts of it!

This is the original cube!

This is how I want to cut it... I made this with paint!

Select the face where you want the window,

press E to extrude and move the newly created wall in the direction you want the extrusion.

You can delete then the selected face.

EDIT Another quick way to make a window is using the inset tool.

Select the face on which you want to make the window, press I and drag the mouse. That will create a new face of similar proportions connected to the edges of the original wall. Then extrude by pressing E and dragging the mouse to create the depth for the window.


I accidentally set an object as camera, how do I undo this? I have a problem with rendering in cycles.
In blender render my object is rendering fine, but in cycles when I pushed F12 I got only this:

One more thing: when I click 0 on keyboard I'm not in camera persp, but in object as camera, it looks like invisible layer, I don't know how to undo this, and be in camera persp again.

Does anybody have any idea how to fix this?

If you accidentally set an Object as Camera (CtrlNumpad 0 will do that)

You have two options to reset the camera back to the "active camera"

In properties windows/scene select your camera as "camera"

Or on the 3D layout select the camera and press
CtrlNumpad 0 (or use the menu: View->Cameras->Select_Active_Object_as_Camera)


How can i make hollow cylinder but to be closed on top and bottom only hollow inside? I want to make a cylinder that is hollow that's simple i did: Cap Fill Type > Nothing

But then the cylinder is open from top and bottom. I want it to be closed and hollow only inside hollow or empty and not open on top and bottom.

Then i want to add a door or to cut some nice square on the cylinder side.
In the end i want to convert this to a unity3d object so i can move inside the cylinder.

The problem is how to make it hollow/empty without keep the top and bottom open?
How to cut/make door ?
How to convert to unity3d object ?

I did this simple tutorial:

Hollow Cylinder

Add a circle mesh.

After that, go into edit mode and extrude it down by selecting all the vertices, pressing E, and then dragging down on the z-axis. Then, select  all the vertices on one side of the cylinder you just made and press F to fill it in, then do the same on the other side. You can use box select to select all the vertices faster (press B and drag out).


Plastic material for a dice I'm working on a material for a dice. My first attempt below has a more velvet look:

Then I've downloaded a material from Blendswap with this outcome:

I like the top of the dice, but the rest is not OK. After finding a tutorial on how to create a glossy plastic the dice looks like this (I used the same red color for the diffuse and glossy shader):

I've used the same red color for the diffuse and glossy shader which results in a less plastic look. After changing the color of the glossy shader to white the dice looks like:

The top looks more plastic, but the rest is not quite what I want.

Question

How can I improve my material to get a 'realistic' plastic look for my dice? Below you can find a screen shot of my current setup:

After removing the relecting floor (and a little adjustment of the lighting and applying the material setup as above) I got the outcome shown below. I am sort of pleased with the plastic look but now I have lost my reflective floor ....and I don't like that. How to create an image with the plastic look and the reflective floor ??? Or would that be a Photoshop job ?

I am looking for a plastic material like this or this.

I'm a beginner and I'd appreciate a explanation or some instructions how to achieve this. Thanks.

maybe the problem is the light bouncing from the floor to the dice.
-try to do it in blender render.
-put the floor in other layer(2).
-select the lamp.
-click the "this layer only".
-make sure that the dice and the lamp are in the same layer(1).
-select the two layer(1),layer(2).
-then render.......


Adding thickness to a mesh in Blender I'm using blender to make a basic model of my house and I want to hollow out the inside of the house so that the walls are slightly thicker and there are normals facing both ways, I'm not really sure how to can achieve this. I think it's called shelling?

Also, has anyone got any tips on working on the interior of buildings, because I find it nearly impossible to do so :/

The Solidify modifier could be useful here. Go and check it out.

If you want to do buildings I would highly recommend that you "build" the house, instead of trying to carve it out of a block.

It would be a lot easier to build everything in pieces. Not everything has to be done in one piece in Blender. And you can always merge the Geometry later.

Build walls, cut windows into them. Add the window frames. Etc.

Build the house, dont try and carve it out.


Why is an object stuck to another? So I created a Cube in Blender and then I created an Empty beside the Cube (in object mode). Now, when I move the Empty around, the Cube follows... Why?

You more than likely hit O by accident, this enables proportional editing in object mode just as it does in edit mode and can cause nearby objects to mimic the one(s) being transformed.

Just turn it off by clicking the blue icon or by pressing O again.


Boolean Modifier Dissapearing When I apply a Boolean modifier to say a cube during an animation and link a cylinder as the Boolean object and animate the cylinder going through it, when the cylinder goes all the way through the Boolean modifier disappears on the cube and it becomes solid again, is it possible to make the cube contain the hole through it after the cylinder has passed through it. I have tried the carve feature instead and it still doesn't work. Any help is appreciated, thanks.

For animaton you need to create keyframes, that are inserting by pressing I. Creating or removing smf are not a operation that can be keyframed.

Instead of this try to animate displaying of modifier. So do the following:

Go to the 1 frame
Hover cursor on eye icon  and/or camera icon and press I
Go to a frame that you want to hide modifier
Disable modifier (eye icon disables in viewport, camera - in render)
Hover cursor on eye icon  and/or camera icon and press I

It will create an animation, that will hide modifier after chosen frame

For creating a hole, I recommend to create a copy of cylinder, that will not leave a cube, and make them invisible for render:

You can do it in outliner.


Is there a way to store a workspace with a scene & auto-recall it when changing to that scene? In my .blend file i have one scene called Master, which has a VSE containing other scenes in the file as strips.

While editing the other scenes i need to be working in a 3dview panel. While editing the Master scene i need to be in the VSE panel.

Is there a way to specify that a workspace with a big VSE panel 'belongs' with the Master scene, and a workspace with big 3d view panel belongs with all others, so that the appropriate layout is loaded when the corresponding scene is made active. I’d like to not need to manually change the workspace each time I switch between the Master scene and the others in the project.

(I don’t mind using scripting if it’s necessary, but i couldn’t find an ‘active scene changed’ callback in the API so far)

Thanks!

This used to be the default in Blender 2.7x, apparently they removed the function entirely, Here is a workaround:
How to assign different scenes for workspaces in Blender 2.8?
He creates a new window and instead of switching workspaces, he switches windows (ALT - TAB)


Not sure how to use multiple UV layers on one character So one this character I have a UV layer for the face and one for the body. But when I swap between the UV layers to add more texture paint to either map, the UV layer for the face disappears. I don't really know how to keep both layers visible and active to paint on.
Here is the face layer displayed, it still lets me add detail to the objects on this layer.

And here is the body UV layer. I want them both active at the same time. And I'm aware that a lot character meshes use both a layer detailing the face, and one for the rest of the body. But I seem to be missing something when it comes to how to use them both... Does it have something to do with the node setup? I tried applying the UV layers as a material to the head and body in the materials tab of the properties panel, but it didn't seem to work. Thank you all in advance for your help and support, you guys rock!

Not sure if you are asking this, but why didn't you connect the respective UV maps to the image textures? Just like its shown in the below image, create a UV Map node for each image texture and connect the respective UV map to the texture.


How can I decompose a matrix for use in DirectX? I'm writing a custom exporter from Blender that will work with DirectX. I am using as a guideline the DirectX exporter found in Blender 2.76. The Blender export script for DirectX uses the following conversion matrix:

code:

# SystemMatrix converts from right-handed, z-up to the target coordinate system
self.SystemMatrix = Matrix()

if self.Config.CoordinateSystem == 'LEFT_HANDED':
    self.SystemMatrix *= Matrix.Scale(-1, 4, Vector((0, 0, 1)))

if self.Config.UpAxis == 'Y':
    self.SystemMatrix *= Matrix.Rotation(radians(-90), 4, 'X')

matrix:

1, 0, 0, 0
0, 0, 1, 0
0, 1, 0, 0
0, 0, 0, 1

I want to write the components of this matrix so I decompose the matrix like so:

loc, rot, sca = self.SystemMatrix.decompose()

now I convert the rotation from quaternion to euler like so:

eul = rot.to_euler('XYZ')

write components
...

The problem is that when I try to recompose the matrix in my DirectX graphics application I get the wrong matrix...

code to recompose matrix:

Matrix m = Matrix.Scaling(sca.x, sca.y, sca.z) * Matrix.RotationYawPitchRoll(eul.x, eul.y, eul.z)
* Matrix.Translation(loc.x, loc.y, loc.z)

result:

0, 0, 1, 0
0, 1, 0, 0
1, 0, 0, 0
0, 0, 0, 1

In your engine you need to compose the matrix m like this:

Matrix m = Matrix.Translation(loc.x, loc.y, loc.z) * Matrix.RotationYawPitchRoll(eul.x, eul.y, eul.z) * Matrix.Scaling(sca.x, sca.y, sca.z)

# matrix_world = matLoc * matRot * matScale


Changing color of a part of an object I cannot find a way how to change a color to another, say "yellow" of a quadrangle on the torus surface.
I'm also interested in the possibility of changing an entire concentric circle of quadrangles around the torus to some other specific color.

First make sure you are in 'Display material preview mode'

add new material to the object via '+' button.

Go to edit mode. Select the desired faces.

Select the desired material, click assign.

Done!


Set Multiple Target Objects Simultaneously I have a number of different objects with similar armatures that I reuse regularly in animation.

Each contains multiple bones with various constraints and drivers that have to reference other objects in the scene to work. The reference objects change based on the scene and so I'm looking for a way to streamline this process.

Simplified example:
I have a cube with an armature with two bones. Each bone has a constraint and each a driver. The constraints and drivers all need to reference the same object. Currently I'd have to do each one manually.

I'd like to know how one might go about setting all four references at once. By having three all reference one or by having all four reference something else (a custom "Set Target Object" panel in the UI somewhere??). I assume this can only be done via addon or a script but any way of speeding this up is greatly appreciated.

Thanks for your assistance.

Something like this:

import bpy
from bpy.props import StringProperty

def apply_target(self, context):
    arm = context.active_object
    pbones = arm.pose.bones
    #update drivers
    for driver in arm.animation_data.drivers:
        for v in driver.driver.variables:
            for target in v.targets:
                target.id = bpy.data.objects[arm.my_target]
    #update contraints
    for bone in pbones:
        for constraint in bone.constraints:
            constraint.target = bpy.data.objects[arm.my_target]

class HelloWorldPanel(bpy.types.Panel):
    """Creates a Panel in the Object properties window"""
    bl_label = "Hello World Panel"
    bl_idname = "OBJECT_PT_hello"
    bl_space_type = 'PROPERTIES'
    bl_region_type = 'WINDOW'
    bl_context = "object"

    @classmethod
    def poll(cls, context):
        return context.active_object is not None and context.active_object.type == "ARMATURE"

    def draw(self, context):
        layout = self.layout

        arm = context.active_object
        scene = context.scene

        row = layout.row()
        row.prop_search(arm, 'my_target', scene, 'objects')

def register():
    bpy.utils.register_module(__name__)
    bpy.types.Object.my_target = StringProperty(update=apply_target)

def unregister():
    bpy.utils.unregister_module(__name__)
    del bpy.types.Object.my_target

if __name__ == "__main__":
    register()


How to check if an object has a particle system or other modifiers I have a few objects in my scene and I sort them in collections based on the some parameters of the applied particle systems. No problems here. I would also like to check if an object has a particle system applied or something like a collision modifier. How would I go about doing that?

I have tried the len(obj.particles_systems) == 0 as my condition but that didn't work.

Thank you in advance!

The modifiers type are given here.

And you can simply test the type you want from that (including 'PARTICLE_SYSTEM' or 'COLLISION').

Here, they are simply printed:

import bpy

obj = bpy.context.object

for modifier in obj.modifiers:
    print( modifier.type )


How to make soft-body sphere stay inside concave object? So, I have a soft body sphere inside a 'maze', (this is just the beginning of it) like this...

The sphere has soft body settings of:

The maze had settings of:

However, as soon as I played the animation, the sphere squished and jumped out the back part of the maze... What I wanted it to do was roll down the ledge.

NOTE: This may be a duplicate, but I've looked up around the place and nobody has had the same problem as me (that I've seen).

The physics solver tries to minimise the work it does by making approximations. You can increase the number of steps the solver will calculate and the number of iterations attempted to improve the detail of collisions.

On the Scene tab under Rigid body settings there is "Steps per second" and "Solver iterations"

But be wary, increasing them too much will slow the simulation time significantly.


Uneven particle system fall on a mesh object I created a distorted torus object, and I used particle system (hair) to put particles on it... I have 2 problems: the particles were not spread evenly on the object (I also used weight paint and vertex group to paint red every side of the object but it didnt change much although the hair system looks more even but not the particles) how can I fix this?
My second problem is that I want my particle mesh object to stick to my main object from one particular side of itself not from everyside... My particles are sesame seeds and some of them stick to my main object from their narrow sides not from large sides .. How can I fix this?

To the rotation problem: you can change in the rotation tab the phase, which rotates all particles in the same angle. You can then randomize the phase a bit to get a more realistic result.
To your distribution problem: I cant really give you a solution for that. I recently ran into similiar problems. What i can tell you is, you need a god topology for the particle system, so more or less even size of your faces (maybe use a remesh modifier). I personally fixed my problem with the weight paint and the distribution by starting over with a complete new emitter object...


How to increase the time length of the animation without slowing it down? I'm new to blender and have to make a 10-second animation of a walk cycle. The walk cycle I created only lasts for about 2 seconds. How would I be able to increase this to 10 seconds with it looping without increasing/decreasing the speed of the animation?
Thank you.

If you go to the Graph Editor panel, select each "string"/line (these lines represent the way Blender handles the animation data), go to the modifiers tab (This is not the one in the Properties panel, press T if the right-side panel is not visible. You should see a Modifiers tab there.), add a Cycles modifier, and you should the have a repeating animation. Some tweaking may be necessary for it to work correctly. You should need to have the animation repeat five times.


Cycles render showing up black and weird I'm trying to make an awesome render of an office building in Blender 2.7. Here's what it looks like in my 3D workspace view so far.

I've been toiling over the wire frame and 3D aspects of it, and then checking to see how it actually renders periodically. When I first started, it seemed to be rendering just fine. But then, when I was about 25% of the way done with building my model, I clicked render and this weird black image of it shows up.

Also, I'm quite certain that it doesn't have to do with the lighting, as I have 4 lamps placed around the scene. I'm starting to get a little concerned that when I'm all done with pouring hours into this, I'm not going to be able to render it properly. Does anyone know what might be going wrong?

edit: I tried adding a white material to the floor part with the chairs on it, but it showed up like this:

Here is the .blend:

The problem is that your entire building has a material on it "realistic glass"

Take this off and viola problem solved. If you would like to put glass on one part of the mesh see this question.


Why is there a black shadow on my baked image? not sure how to explain this so apologies if this doesn't make complete sense, but I am having the hardest time with my baked image. For some odd reason, there is some black shadow circle on a part of my baked image that I have no idea why it is there? In the view, there is no shadowing like that so I don't know why it shows up when it's baked. There is also some weird light strip too, which again is not shown in the original.

If someone knows how to get rid of these issues I would be so appreciative because I'm ready to give up in frustration.

This is likely a result of the ambient occlusion image. If this doesn't show up in the final render then it probably isn't an issue.


Object Physics Don't Work for Rotation Alright: I'm new to blender and for the last several days I've been struggling with a problem with the rigid body physics. Here's how it goes:

Open new blender project
Change to cycles render
Import 3D model (swivel chair)
Add active physics to swivel chair (rigid body)
Add passive physics to plane
Click play (animation plays)
Chair falls... then stays 100% upright, not rotationally affected by impact

https://i.imgur.com/nnmFmUU.png

Under the physics tab of the property panel set the Shape to Mesh. The convex hull is like a shape drawn around the mesh with no concave angles, so the feet of the chair might behave unexpectedly, as if there's just a flat plane or a few flat triangles on the bottom. It also has some degree of approximation, it doesn't create a new point for every point on your mesh.

I don't think there's a way to visualize the convex hull that Blender generates for an object. It probably looks a bit like this but with more triangles and different triangulation pattern.

Your chair mesh might not be entirely suitable for collisions if it is non-manifold, particularly if it has open backfaces. If this is the case you can create a separate mesh just for collisions that represents the shape of the object but not it's appearance. You would then parent the chair mesh to the collision mesh so it moves exactly with it, and then hide the collision mesh from rendering so it doesn't cover the chair.

Finally, change the Bounciness under Surface Response of the chair and the surface your chair is landing on. When Bounciness is set to 0 the surface stays impossibly still and doesn't apply any force to the object landing on it regardless of how bouncy the falling object is. Likewise a falling object with Bounciness zero appears to receive no force when it's Bounciness is 0. Most objects should have at least some amount of bounciness in order to behave as expected.


When I render an image it comes out different than what I see in the viewport. How can i fix this? As you can see the bevels in the viewport on the front pyramid are much smaller compared to the rendered image. This is an Eevee render.

Do you have any modifiers (e.g. subdivision), which have different parameter settings for "Viewport" and "Render"?

If so, setting the number to the same value should give you a consistent result!


How to change the color of clipping border display? Clipping border (Alt B) makes a dark box around the selected area:

Setting the background color to the same color as the box doesn't work if you have Only render enabled.

How to make the box transparent instead?

Related BA thread.

There is a setting for 'Clipping Border' now in newer version of Blender.
themes / preferences / 3dview / clipping border color option box.
The default color is a dark grey, and the setting for transparency is called 'A' for Alpha Value. The default Alpha is 1 which is Opaque, if you move the slider to '0' the View Clipping Background is Transparent!


Geometry Nodes instancing faces How to make Instancing Faces and aligned to face normal in Geometry Nodes?

Use Align Rotation to Vector, Vector should be "normal" and axis Z (for default cone):


How to change curve type? I've created a bezier curve but now I want to change its type to path.
How to achieve this?
And btw. if I can animate both: bezier curve and path, what is the practical difference between those?

Okay, so there are two main kinds of curves in Blender. Bézier and NURBS. A path is a NURBS curve and you want to convert a bezier curve to it. To do this is really easy:

Click on the bezier curve in question.
Press Tab
Select the bezier curve by pressing A
Press Space and search for "Set Spline Type"
Click "NURBS"

Now you have a "path" or NURBS curve to work with. I found this solution in reverse on here.

As for the practical difference between the two, as far as i can tell, the NURBS curve is more accurate and precise than its bezier counterpart. I hope this helps.


Grey screen while rendering (First Post Here so sorry if I did something wrong while posting) I recently decided to render a car, but when I pressed the render button I was greeted with a Grey Screen. I've been to many other forums and tried their solutions but none of them worked. So I thought maybe I did something wrong and I decided to render the default cube in a new project and nope the same thing happened again.
I tried reinstalling blender and even updating it from 2.82 to 2.83 but nothing worked. And before you ask, Yes the camera button in the layers menu has been selected. After a bit more digging around I found out that a project I made a few months ago might've been the cause for it because every other project before that one renders perfectly. But every project after that one gives me the grey screen.
Link to the project I want to render:
http://www.mediafire.com/file/1mjexg43uugbla3/Honda_Civic_2003AT.blend/file
Link to the project which I think might've caused a problem:
http://www.mediafire.com/file/u4rfu8i8hesxv2n/ElonHuman.blend/file
Thank you

In the Output settings > Post Processing, you've enabled the Compositor option. If I take a look I see an Image node plugged into the Composite node. Plug an Input > Render Layers node instead and it works.


How do i get rid of this red dotted rectangle? I can't figure out how to get rid of this red dotted line in the middle of the viewport.

The red checkered box is a render region.
It's used to render only parts of your screen.
Clear it using Ctrl+Alt+B
Or through View > View Regions

Read: Render Border's related check boxes - How do they work?


Selected mesh will not move in Object mode I just installed Blender 2.82a on my PC and found that the initial cube will not move when selected in object mode. When selected the outline turns yellow, but when I attempt to use the move command the outline turns white and moves, but leaves the cube behind. This happens even if I delete the cube and add a new mesh. If I duplicate the mesh or add other meshes, the new mesh will move but will use the other mesh as its reference. I have uninstalled and reinstalled several times to no avail. I also installed Blender 2.82a on my Wacom companion 2 and it works perfectly. I have embedded a screencast on my website that illustrates the issue. https://www.artforthismortalcoil.com/blenderscreencast

I just find a way to fix it, changing to Edit mode, do anything with object (as move points of object) then come back Object mode. Everything will be fixed.


Why the dark objects won't be differenced from the base object? I made the objects by creating a cube in Object mode, going into Edit mode, deleting the vertices, clicking shift+LMB new vertices, making a face and extruding.

On the light colored objects, I can add a Boolean modifier and set it to Difference, and it would make a hole in the base object the shape of the new object. However, inspite of these dark objects were made the same way as the lighter ones, when I try to apply a Boolean modifier, it deletes the base object.

In Edit Mode select all of your vertices and Recalculate the Normals. The option is in your Tool Tab in the Shading/UV's tab (Press the "T" key to toggle the Tool Tab on/off).


Subdivision Surface modifier works badly I try to follow instruction from an old video tutorial of creating a clock. This is what I wanna achieve (I mean smooth edges only):

And this is my work without SubSurf:

This is what I get with Subdivision Surface modifier:

How can I rid of ugly rim / hollow on the left side of screenshot? It looks terrible after rendering! I tried to use different subdivisions numbers and replace it with bevel, but nothing helps.

This is my work from other side without the modifier:

And why did I get this problem if I tried to follow all the steps and proportions of the tutorial?

Update

I highlighted the problem here:

You can try to do Ctrl + R to add a loop cut, click before the sharp vertices you want, and just slide it to the left to sharp the angle
Otherwise you can select the vertices and in the Tool box on the right (with N) click on a thing with crease in the name, or I think you can do Shift + E


Issue animating a 3D text within a scene I'm pretty new to blender and probably missed something obvious, but I couldn't find anything online pertaining to this problem.
I recently created a small animation and I'm aware of the basics. (Add a keyframe, move the timeline, change the object in the way you want it to animate, add new keyframe, etc.)
That animation turned out perfectly, and I rendered it into a video.
A day later, I wanted to add some more to the animation.  I added some 3D text using the "text" option within blender, and positioned it appropriately.  I added a starting keyframe, then rotated the text as I wanted it.  I added a new keyframe.  The text jumped back to it's previous rotation and refuses to move itself.  The keyframe shows itself on the timeline, but no matter what I've tried, the text itself won't move.  Any help at all would be very, very appreciated!
File is here: https://pasteall.org/blend/4e39eebd0c3843298554a7d1555657e2

Your animation is there, it's working for me, the only thing that i'm not sure if it's something that you did, is the Time Remapping (output Properties > Time Remapping) this is showing a new remapping of 200, so the keyframe is in Frame 130 + the time remapping = Frame 230


How to make objects in the scene become physically smaller the further they are from the camera? My camera is in orthographic mode so there is no depth. I want to create a fake sense of depth by making the objects in the scene become physically smaller the farther away they are from the camera or a specified point. Is there a way to do this?

You can do this by drivers.

Right click on Scale X property and Add Driver > Manually Create Later (Single).

Go to Graph Editor and switch to Drivers mode.
Draw a line like this: (this line will show dependence between distance and scale)

In Drivers tab change value to distance, select both objects in Object 1 and Object 2 inputs and swich Type to Averaged value

Update Dependencies. You will see that x-scale now depends of distance between objects:

Finally copy y and z scale from x. Paste #self.scale.x in Scale Y and Z

To makes this work, you need to enable Use self in Drivers tab on Scale Y and Z channels.

Update Dependencies.


Any way to get a multilayer video? So I have an animation that I am trying to render in cycles. It takes about 20 mins per frame (my pc isn't amazing) and is 200 frames. I want to render the animation overnight, close the program and come back to it later.
Question:
Is there any way to close a project after rendering, and be able to edit in the compositor after?
I know that you can do this with MultiLayer EXR files, but thats for pictures. How would I get a multilayer video?
Or is just any way to not have to composite the whole render in one go, and be able to close the program
Sorry in advance if this is already answered, I looked but found nothing.

First render out your animation with the OpenExr Multilayer setting, into an image sequence.

Then load the image sequence into the compositor (can be on a separate blender instance), with the Input -> Image Sequence node

Do whatever composite you desire.

Then in the Output properties tab, set your frame start and end, then change the output format to ffmpeg video. Open up the encoding tab that appears, and change the container and encoding settings to what you want.

Render the animation (Ctrl + F12) (find the output video file in the folder specified under Output. It should be named something like 0001-0250.mkv or similar)


IES light is reflected incorrectly in Cycles I'm trying to use IES file which is 4FT light source and Cycles renders a reflection of it as a simple spot. If I try to use that IES on Area light instead of Point light to get an actual 4Ft rectangle, IES data simply doesn't work and it just is a regular Area light. As far as I know IES only works with Point lgiht source anyway.
In comparison I used the same files in 3Ds Max and it reflects a proper rectangle. Are IES lights simply broken in Blender?
Thank you

Problem solved. I used a simple mesh and applied emission to it with IES. But mesh itself should be exactly close to IES parameters. For example 4'x2" rectangle. In that case IES texture is displayed correctly. If your mesh is different from what IES is supposed to cover, you won't get right result.


more than one vertex group for one bone I'm asking if there is anyway in blender to make more than vertex groups assigned to only one bone? lets say I have a only one bone in cube and I want to assign four different groups representing the four corners of the cube. If anyone could please advise how to do that as from what I know that to link vertex groups with bones the names needs to be the same, but in my case there will be only one bone name and four different vertex groups names, so then how I'm gonna link those four vertex groups with this one bone if they have different names?

You can not assign more than one Vertex Group to one Bone. However you can assign many vertices to a vertex group where each vertex may have different weight. And that should be exactly the solution for which you are searching.

There is no benefit from splitting the weights for one single bone into different vertex groups. Even if that would be possible, blender had to merge the groups anyways before it could apply the weights to the vertices.

Please also check the wiki documentation about vertex groups:

https://docs.blender.org/manual/en/dev/modeling/meshes/properties/vertex_groups/index.html

You should read all 4 chapters of that section.


UV mapping PS to Blender I've imported my texture onto my mesh which is UV unwrapped (Lots of Booleans were used) the text appears on the UV, but it wont appear in the viewports. What am I doing wrong?

Thank you.

You shouldn't combine image and noise texture that way.
If you need a non-smooth surface, just use it as a Bump map.

Connect image texture into Base Color input
Use Noise texture with the Bump node and connect it into Height
Connect the Bump node into Normal input

Other observations:

avoid n-gons, they cause bad shading and prevent loopcuts, proper beveling, etc.
use linked duplicates - similar buttons can share the same mesh yet be independently moved/rotated
the main area has 3.74° tilt. Make sure your buttons are tilted consistently.
don't plug Noise texture node into the Specular input, if you're going for realism.
Avoid extreme values in the Noise texture. Use White Noise for fine grain.

Use quads (and tris) when possible.


How can I access displacement modifier z coordinates in the shader editor? I am trying to create a heatmap style of animation from a black and white image sequence.
So far I created a grid, applied the image sequence as a texture and then added a displacement modifier.
As long as I don't click 'apply' on the modifier, it updates with each frame -> perfect. I also activated the options, that the mesh is updated in edit mode. However, somehow the texture coordinates node does not recognize the new z-positions, unless I click apply on the modifier. But then, it's not dynamic to the image sequence texture.
For the moment, I created a workaround by not choosing the "generated" texture coordinates, but the "reflection" option. However, this may ressemble the actual z- positions, but is not acurate enough for me as it also changes with the viewing angle.
Any suggestions?
Displacement modifier:

Current node setup:

"Reflection" heatmap:

Your modifier displaces the geometry by +/- 1000 units (I suggest setting the midlevel back to 0.5 by the way), but your color ramp only effectively differentiates colors in your geometry between 0 and 1 units.
You could also set the midlevel to 0, and set your plane origin to geometry so that the displacement only raises the geometry.
I'm saying that because you should use the "Object" output which Z coordinate will be negative if it is located under the object origin. That way you can deal with this information only by dividing the Z coordinate by the strength of your modifier. That will give you the full range of height of your mesh, normalized between 0 and 1, perfect for a color ramp.
In short : Use the object output, but move the origin of the object lower (or raise your geometry in edit mode) and plug a math node set to divide by [the same strength as your displace modifier] between the separate XYZ and the color ramp node.


How to render specular highlights as a separate image with alpha channel? I'm using the Blender Cycles engine to create graphics for a game; specifically, I want to display a grid of coloured ellipsoid counters for the player to move around.  To avoid creating a separate image for each colour, I want to store a single greyscale image in the resources, and apply a colour tint at runtime:

However, with this approach, the specular highlights would also be tinted; so I would like to store the highlights as a separate image with an alpha channel, and overlay it on top of the tinted image.

I've tried Googling for ways to do this in Blender, and cannot find anything.  The best solution I can think of is to set the glossy BSDF colour to red (1.0, 0.0, 0.0) and the diffuse BSDF colour to green (0.0, 1.0, 0.0):

I would then need to create a mask from the red channel, and create base and overlay greyscale images from the green and red channels respectively, either as a manual step in Gimp, or (better) store a single image in the resources and do the channel operations in code:

While I realise that I'm probably subverting the properties of light for the sake of coding simplicity, I am concerned that I may not be getting the most believable results.  Given that the rendering engine knows more about the light paths than I do from the final image, is there a way to do this in Blender?

Thanks!

UPDATE

For posterity, these are the material nodes I ended up with:

With a further change to adjust the alpha channel on the highlight image, these are the compositing nodes I created:

Finally, this is the end result, after tinting and overlaying in the game source code:

You should add in the specular with color, not mix shaders. In that way you will get a white highlight.

Here I'm using color ramps to make a mask for transparency and removing some of the gray on the specular before adding it to a solid color.

You can also render out Diffuse and Glossy and use the Compositor to choose color.

You need to add light passes for gloss direct and diffuse direct

The new passes can be then be exported from the Compositor via Image editor (set the image to be "Viewer Node") and then saved from there Image->Save As...


add controls to already generated meta rig I saw some answers to similar question here, but either it doesn't match my needs or I did not understand them.

Long story short: I didn't change rigify type on the fingers to super_finger but I already did the weight repaint job and generated the rig. Do I have to redo the whole thing? Is this losted hours of work?

full story:
My problem is I have an already generated metarig. I did aaaaall the weight paint corrections (there was a lot because I added few custom bones to the original armature, like a bag, some swords etc) But when I started animating, I noticed there was no controls for the fingers (you know, the lines you select and scale to retract fingers) I found out on stackexchange that I should change the rigify type on those fingers to super_finger instead of tentacles. Do I have to regenerated the whole thing and redo the whole weight repaint job again?

Thank you

The weights are properties of the vertex groups, so they belong to the mesh object, no matter which rig you use. They get overwritten only if you perform an automatic weighting or a "with empty group" option.

So you can create the new rig and parent it to the mesh using the simple "Armature deform" option.

The names of the new rig bones should be the same as the old, so everithing should work fine (except for the new fingers bones, of course).

Later you can also perform an automtic weghting limited to the new fingers bones, to have a good starting point to be refined with weight painting or direct weight assign.


How can I set the object origin for an armature? After importing a .bvh file from Motion Capturing, the object appears translated and its origin isn't in the objects geometric center. I've tried several options from the Set Origin menu (Shift + Ctrl + Alt + C).

However, I still couldn't find a way to have the object's center work in both Object Mode and Edit Mode. When I toggle between the two modes, the object jumps around.

How can I set the object's center for both modes?

Edit Mode:

Object Mode:

In the Edit mode, the pose set in an armature is ignored.  Because in your case the object is translated in an unwanted way in the Object mode but not in the Edit mode, it is possible that you have accidentally set a pose which translates the whole object.

To clear the translation of a pose, do the following.

Select the armature and enter the Pose mode.
Select a bone you want to reset the translation of (or select all bones by using shortcut A if you want).
Press Alt+G (the shortcut for Pose > Clear Transform > Location).

In response to your comment, here is how to clear the keyframes for the bone translation (that is, remove the animation data of the bone location from all frames).

Select the armature and enter the Pose mode.
Select the bone, and open the Bone tab in the Properties window.
Right-click any of the three coordinates in Location, and select Clear Keyframes.

After clearing the keyframes, you can use Alt+G to clear the translation.

However, because this works for only one bone, if you want to do this for many bones, you have to repeat steps 2 and 3 many times.  Maybe there is a better way.


How to make an object bounce with physics i am trying to create an animation where a stretchy "i" bounces on a tnt switch...i thought of creating the bounce with just animation but know i have no idea on how to make the lever as in the picture react to it(move downwards as the "i" bounces)...all i need is pointers on how to do it any help will be appreciated

Seems like an old thread, I was trying to bounce a ball on a plane. There is bounciness property on rigid body. Changing it to more than 0 on both the bodies, result in a bounce


How can i disconnect part of mesh, reconnect it to another part and make it a part of different UV island? I was modifying a boot model consisting of several meshes and ran into a big problem. I have two main mesh parts: the sock (top image on the left) and the boot (top image on the right). I need to disconnect a part of sock (bottom image on the left) and reconnect it to the boot mesh. I tried doing this by hitting the Y short key but this creates additional vertices which messes with the export script. So i need to disconnect and reconnect without changing the total vertex/edge/face count.. I also need the repositioned bit to become a part of a different UV island (bottom image on the right - i sort of drag-and-point where i want the piece to move to). Again, i can't unwrap because blender creates a totally different layout.. I'm almost positive that it's just impossible to do all that but maybe i'm missing something. I've spent 6 hours modifying the model before i realized there was a problem...

This is old question but I'd figure I'll post possible answer anyways because someone else might google this.

I'd just pin (select these verts and press p) the vertices in uv editor that need to stay put. Leave all seams unpinned. Then just press u and do basic uvunwrap the whole mesh. Only those vertices that you wanted to move should move. If you get weird result then you probably have a missing seam, wrong vertice pinned, hidden geometry in edit mode or something else. After the uvunwrap press alt-p in uv editor to get rid of the pin tool.


How to create a custom UI? I was watching this video on making a custom UI tab using Python, and in the line from bpy.types import Menu, Panel, UIList, I see the names of objects that look like they can all be used to make different UI elements. Does bpy.types contain all the objects that people use when they want to make custom UI elements?

Designing an UI or Add-on is basically a combination of supplying Properties and the inheritance of built-in Type classes (Panel, Operator, Menu etc.).

Properties
Start by defining your Properties first. Properties are basically 'data types' and can be displayed in the UI for basic user interaction. Note that you can access the value of each property from almost everywhere. To populate a complete list in the console use python's dir() method on bpy.props :

Click to enlarge
Property Appearance

Define a BoolProperty for a 'Checkbox'
Define a FloatProperty or IntProperty to get a 'Slider'
Define a StringProperty for all different kinds of 'Character Input' or 'File Paths'
Define an EnumProperty to get a 'Dropdown Menu'
Define a FloatVectorProperty or IntVectorProperty for compound values eg. 'Color Pickers', 'Location Coordinates', 'Velocity Vectors', 'Matrices' etc.
...

Property Definition
from bpy.props import (StringProperty,
                       BoolProperty,
                       IntProperty,
                       FloatProperty,
                       EnumProperty,
                       )

my_bool : BoolProperty(
    name="Enable or Disable",
    description="A bool property",
    default = False
    )

my_int : IntProperty(
    name = "Set a value",
    description="A integer property",
    default = 23,
    min = 10,
    max = 100
    )
...

Note that as of Blender 2.8x, properties should be assigned to variables using a single colon : instead of the usual assignment operator = like in Blender 2.7x or older versions of Blender.

Types
The contents of bpy.types are class templates built for inheritance.
Panel
Panels are everywhere in Blender so it's the most basic element of the user interface. Where the panel is going to be used is defined by bl_space_type. Blenders interface is 'context sensitive' so you can define bl_context to get the Panel in one respective Mode (Object Mode, Edit Mode etc.).

class HelloWorldPanel(bpy.types.Panel):
    bl_idname = "OBJECT_PT_hello_world"
    bl_label = "Hello World"
    bl_space_type = 'PROPERTIES'
    bl_region_type = 'WINDOW'
    bl_context = "object"

    def draw(self, context):
        self.layout.label(text="Hello World")

bpy.utils.register_class(HelloWorldPanel)

Sub Panels

As of Blender 2.8x we can have sub panels by assigning a certain panel (parent) to bl_parent_id:
import bpy

class HelloWorldPanel:
    bl_space_type = "VIEW_3D"
    bl_region_type = "UI"
    bl_category = "Tools"
    bl_options = {"DEFAULT_CLOSED"}

class HELLO_PT_World1(HelloWorldPanel, bpy.types.Panel):
    bl_idname = "HELLO_PT_World1"
    bl_label = "Panel 1"

    def draw(self, context):
        layout = self.layout
        layout.label(text="This is the main panel.")

class HELLO_PT_World2(HelloWorldPanel, bpy.types.Panel):
    bl_parent_id = "HELLO_PT_World1"
    bl_label = "Panel 2"

    def draw(self, context):
        layout = self.layout
        layout.label(text="First Sub Panel of Panel 1.")

class HELLO_PT_World3(HelloWorldPanel, bpy.types.Panel):
    bl_parent_id = "HELLO_PT_World1"
    bl_label = "Panel 3"

    def draw(self, context):
        layout = self.layout
        layout.label(text="Second Sub Panel of Panel 1.")

classes = (
    HELLO_PT_World1,
    HELLO_PT_World2,
    HELLO_PT_World3
)

def register():
    for cls in classes:
        bpy.utils.register_class(cls)

def unregister():
    for cls in classes:
        bpy.utils.unregister_class(cls)

if __name__ == "__main__":
    register()

See also: Text Editor > Templates > Python > UI Panel.
Operator
The Operator is the most important bit to understand. You can display 'operators' as Buttons and once registered and you can call it from everywhere via bpy.ops.IDNAME(). That's also the way blender is designed, all real Buttons are 'operators' under the hood, mostly written in C but then exposed to python. See also: Text Editor > Templates > Python > Operator....

class HelloWorldMinimal(bpy.types.Operator):
    bl_idname = "wm.hello_world"
    bl_label = "Minimal Operator"

    def execute(self, context):
        # Report "Hello World" to the Info Area
        self.report({'INFO'}, "Hello World")

        return {'FINISHED'}

bpy.utils.register_class(HelloWorldMinimal)

# test call the operator
bpy.ops.wm.hello_world()

The Operator class template comes with predefined methods, in fact poll, invoke, execute, draw, modal, and cancel which can be used along custom properties for all different kinds of operations and also to provide user interaction. More complete example of an operator:
class HelloWorld(bpy.types.Operator):
    bl_idname = "wm.hello_world"
    bl_label = "Minimal Operator"
    bl_options = {'REGISTER'}

    # Operator user properties, should be assigned using a single colon :
    # instead of using an equal sign = in Blender 2.8
    report_flag: bpy.props.BoolProperty(
        name = "Report",
        default = True)

    @classmethod # Will never run when poll returns false
    def poll(cls, context):
        return context.object

    def invoke(self, context, event): # Used for user interaction
        wm = context.window_manager
        return wm.invoke_props_dialog(self)

    def draw(self, context): # Draw options (typically displayed in the tool-bar)
        row = self.layout
        row.prop(self, "report_flag", text="Report Hello World")

    def execute(self, context): # Runs by default
        if self.report_flag:
            self.report({'INFO'}, "Hello World")
        else:
            print ("Hello World")
        return {'FINISHED'}

bpy.utils.register_class(HelloWorld)

# For interaction, pass 'INVOKE_DEFAULT' when calling
# the operator, this way invoke runs before execute method
bpy.ops.wm.hello_world('INVOKE_DEFAULT')

Further reading: How to call a confirmation dialog box? (for tremendously dangerous operators).
Menu
For a custom menu define/inherit a Menu Class. Add your operators and properties to the draw() function properly (see also: Text Editor > Templates > Python > UI Menu templates).

class SimpleCustomMenu(bpy.types.Menu):
    bl_label = "Simple Custom Menu"
    bl_idname = "OBJECT_MT_simple_custom_menu"

    def draw(self, context):
        layout = self.layout

        layout.operator("wm.open_mainfile")
        layout.operator("wm.save_as_mainfile")

# The menu can also be called from scripts
bpy.ops.wm.call_menu(name=SimpleCustomMenu.bl_idname)

You can also draw a button to call the menu without declaring any extra operator by layout.operator("wm.call_menu").name="bl_idname"
Submenu
To get a submenu, call the second one within the parent menu via layout.menu(bl_idname).

class MyCustomMenu(bpy.types.Menu):
    bl_label = "First Menu"
    bl_idname = "OBJECT_MT_custom_menu"

    def draw(self, context):
        layout = self.layout
        layout.label(text="Hello First Menu!", icon='WORLD_DATA')

         # call the second custom menu
        layout.menu("OBJECT_MT_sub_menu", icon="COLLAPSEMENU")

class MyCustomSubMenu(bpy.types.Menu):
    bl_label = "Sub Menu"
    bl_idname = "OBJECT_MT_sub_menu"

    def draw(self, context):
        layout = self.layout
        layout.label(text="Hello Second Menu!", icon='WORLD_DATA')

        # call another predefined menu
        layout.operator("wm.call_menu", text="Unwrap").name = "VIEW3D_MT_uv_map"

# draw a button within the panel to call the first menu
class OBJECT_PT_my_panel(bpy.types.Panel):
    ...
    def draw(self, context):
        layout.operator("wm.call_menu", text="Call My Menu").name = "OBJECT_MT_custom_menu"
        ...

All in One
When creating an Add-on, usually a lot of properties are requiered. For a better organisation you can create a 'settings class' by using a PropertyGroup.Note that as of Blender 2.8x, properties should be assigned using a single colon : instead of the usual assignment operator =.
2.7x
class MySettings(PropertyGroup):

    my_bool = BoolProperty()
    my_int = IntProperty()
    my_float = FloatProperty()
    ...

2.8x
class MySettings(PropertyGroup):

    my_bool: BoolProperty()
    my_int: IntProperty()
    my_float: FloatProperty()
    ...

Also, as of Blender 2.8x module/class registration has changed to prevent name conflicts. bpy.utils.register_module(__name__) isn't available anymore so you basically have to register/unregister each class separately or within a loop (best practice):
classes = (
    WM_OT_HelloWorld,
    OBJECT_PT_CustomPanel,
)

def register():
    from bpy.utils import register_class
    for cls in classes:
        register_class(cls)

def unregister():
    from bpy.utils import unregister_class
    for cls in reversed(classes):
        unregister_class(cls)

Note that in addition to the old naming conventions you also have to add a seperator like _OT_, _MT_ or _PT_ to the name of your class based on the inherited class type (Operator, Menu, Panel).

Add-On Template
The following Add-on appends a custom panel to the Tool Shelf of the 3D View and prints the current 'user values' of all custom properties to the console:

Blender 2.7x
    bl_info = {
    "name": "Add-on Template",
    "description": "",
    "author": "",
    "version": (0, 0, 2),
    "blender": (2, 70, 0),
    "location": "3D View > Tools",
    "warning": "", # used for warning icon and text in addons panel
    "wiki_url": "",
    "tracker_url": "",
    "category": "Development"
}

import bpy

from bpy.props import (StringProperty,
                       BoolProperty,
                       IntProperty,
                       FloatProperty,
                       EnumProperty,
                       PointerProperty,
                       )
from bpy.types import (Panel,
                       Operator,
                       PropertyGroup,
                       )

# ------------------------------------------------------------------------
#    Scene Properties
# ------------------------------------------------------------------------

class MySettings(PropertyGroup):

    my_bool = BoolProperty(
        name="Enable or Disable",
        description="A bool property",
        default = False
        )

    my_int = IntProperty(
        name = "Int Value",
        description="A integer property",
        default = 23,
        min = 10,
        max = 100
        )

    my_float = FloatProperty(
        name = "Float Value",
        description = "A float property",
        default = 23.7,
        min = 0.01,
        max = 30.0
        )

    my_string = StringProperty(
        name="User Input",
        description=":",
        default="",
        maxlen=1024,
        )

    my_enum = EnumProperty(
        name="Dropdown:",
        description="Apply Data to attribute.",
        items=[ ('OP1', "Option 1", ""),
                ('OP2', "Option 2", ""),
                ('OP3', "Option 3", ""),
               ]
        )

# ------------------------------------------------------------------------
#    Operators
# ------------------------------------------------------------------------

class WM_OT_HelloWorld(bpy.types.Operator):
    bl_idname = "wm.hello_world"
    bl_label = "Print Values Operator"

    def execute(self, context):
        scene = context.scene
        mytool = scene.my_tool

        # print the values to the console
        print("Hello World")
        print("bool state:", mytool.my_bool)
        print("int value:", mytool.my_int)
        print("float value:", mytool.my_float)
        print("string value:", mytool.my_string)
        print("enum state:", mytool.my_enum)

        return {'FINISHED'}

# ------------------------------------------------------------------------
#    Menus
# ------------------------------------------------------------------------

class OBJECT_MT_CustomMenu(bpy.types.Menu):
    bl_idname = "object.custom_menu"
    bl_label = "Select"

    def draw(self, context):
        layout = self.layout

        # Built-in example operators
        layout.operator("object.select_all", text="Select/Deselect All").action = 'TOGGLE'
        layout.operator("object.select_all", text="Inverse").action = 'INVERT'
        layout.operator("object.select_random", text="Random")

# ------------------------------------------------------------------------
#    Panel in Object Mode
# ------------------------------------------------------------------------

class OBJECT_PT_CustomPanel(Panel):
    bl_idname = "object.custom_panel"
    bl_label = "My Panel"
    bl_space_type = "VIEW_3D"
    bl_region_type = "TOOLS"
    bl_category = "Tools"
    bl_context = "objectmode"

    @classmethod
    def poll(self,context):
        return context.object is not None

    def draw(self, context):
        layout = self.layout
        scene = context.scene
        mytool = scene.my_tool

        layout.prop(mytool, "my_bool")
        layout.prop(mytool, "my_enum", text="")
        layout.prop(mytool, "my_int")
        layout.prop(mytool, "my_float")
        layout.prop(mytool, "my_string")
        layout.operator("wm.hello_world")
        layout.menu(OBJECT_MT_CustomMenu.bl_idname, text="Presets", icon="SCENE")
        layout.separator()

# ------------------------------------------------------------------------
#    Registration
# ------------------------------------------------------------------------

def register():
    bpy.utils.register_module(__name__)
    bpy.types.Scene.my_tool = PointerProperty(type=MySettings)

def unregister():
    bpy.utils.unregister_module(__name__)
    del bpy.types.Scene.my_tool

if __name__ == "__main__":
    register()

Gist: https://gist.github.com/p2or/a00bdde9f2751940717a404cf977dd01
Blender 2.8x
bl_info = {
    "name": "Add-on Template",
    "description": "",
    "author": "p2or",
    "version": (0, 0, 3),
    "blender": (2, 80, 0),
    "location": "3D View > Tools",
    "warning": "", # used for warning icon and text in addons panel
    "wiki_url": "",
    "tracker_url": "",
    "category": "Development"
}

import bpy

from bpy.props import (StringProperty,
                       BoolProperty,
                       IntProperty,
                       FloatProperty,
                       FloatVectorProperty,
                       EnumProperty,
                       PointerProperty,
                       )
from bpy.types import (Panel,
                       Menu,
                       Operator,
                       PropertyGroup,
                       )

# ------------------------------------------------------------------------
#    Scene Properties
# ------------------------------------------------------------------------

class MyProperties(PropertyGroup):

    my_bool: BoolProperty(
        name="Enable or Disable",
        description="A bool property",
        default = False
        )

    my_int: IntProperty(
        name = "Int Value",
        description="A integer property",
        default = 23,
        min = 10,
        max = 100
        )

    my_float: FloatProperty(
        name = "Float Value",
        description = "A float property",
        default = 23.7,
        min = 0.01,
        max = 30.0
        )

    my_float_vector: FloatVectorProperty(
        name = "Float Vector Value",
        description="Something",
        default=(0.0, 0.0, 0.0),
        min= 0.0, # float
        max = 0.1
    )

    my_string: StringProperty(
        name="User Input",
        description=":",
        default="",
        maxlen=1024,
        )

    my_path: StringProperty(
        name = "Directory",
        description="Choose a directory:",
        default="",
        maxlen=1024,
        subtype='DIR_PATH'
        )

    my_enum: EnumProperty(
        name="Dropdown:",
        description="Apply Data to attribute.",
        items=[ ('OP1', "Option 1", ""),
                ('OP2', "Option 2", ""),
                ('OP3', "Option 3", ""),
               ]
        )

# ------------------------------------------------------------------------
#    Operators
# ------------------------------------------------------------------------

class WM_OT_HelloWorld(Operator):
    bl_label = "Print Values Operator"
    bl_idname = "wm.hello_world"

    def execute(self, context):
        scene = context.scene
        mytool = scene.my_tool

        # print the values to the console
        print("Hello World")
        print("bool state:", mytool.my_bool)
        print("int value:", mytool.my_int)
        print("float value:", mytool.my_float)
        print("string value:", mytool.my_string)
        print("enum state:", mytool.my_enum)

        return {'FINISHED'}

# ------------------------------------------------------------------------
#    Menus
# ------------------------------------------------------------------------

class OBJECT_MT_CustomMenu(bpy.types.Menu):
    bl_label = "Select"
    bl_idname = "OBJECT_MT_custom_menu"

    def draw(self, context):
        layout = self.layout

        # Built-in operators
        layout.operator("object.select_all", text="Select/Deselect All").action = 'TOGGLE'
        layout.operator("object.select_all", text="Inverse").action = 'INVERT'
        layout.operator("object.select_random", text="Random")

# ------------------------------------------------------------------------
#    Panel in Object Mode
# ------------------------------------------------------------------------

class OBJECT_PT_CustomPanel(Panel):
    bl_label = "My Panel"
    bl_idname = "OBJECT_PT_custom_panel"
    bl_space_type = "VIEW_3D"
    bl_region_type = "UI"
    bl_category = "Tools"
    bl_context = "objectmode"

    @classmethod
    def poll(self,context):
        return context.object is not None

    def draw(self, context):
        layout = self.layout
        scene = context.scene
        mytool = scene.my_tool

        layout.prop(mytool, "my_bool")
        layout.prop(mytool, "my_enum", text="")
        layout.prop(mytool, "my_int")
        layout.prop(mytool, "my_float")
        layout.prop(mytool, "my_float_vector", text="")
        layout.prop(mytool, "my_string")
        layout.prop(mytool, "my_path")
        layout.operator("wm.hello_world")
        layout.menu(OBJECT_MT_CustomMenu.bl_idname, text="Presets", icon="SCENE")
        layout.separator()

# ------------------------------------------------------------------------
#    Registration
# ------------------------------------------------------------------------

classes = (
    MyProperties,
    WM_OT_HelloWorld,
    OBJECT_MT_CustomMenu,
    OBJECT_PT_CustomPanel
)

def register():
    from bpy.utils import register_class
    for cls in classes:
        register_class(cls)

    bpy.types.Scene.my_tool = PointerProperty(type=MyProperties)

def unregister():
    from bpy.utils import unregister_class
    for cls in reversed(classes):
        unregister_class(cls)
    del bpy.types.Scene.my_tool

if __name__ == "__main__":
    register()

Gist: https://gist.github.com/p2or/2947b1aa89141caae182526a8fc2bc5a

More complex examples

What ui would work for choosing from a long, long list?
script custom previews in a menu
Create an interface which is similar to the material list box


Why is only the hair based particle system appearing in two levels of particles? I have a plane with Reed sticks applied on as particles in Layer 1.
These Reed stick Particles consisted of a group of objects with their own particles applied on another layer.  These group of particles systems are in layer 2.

When I render the scene I can only see one Particles "called HAIR in the scene" I can not see " SEEDS and LEAVES" particles, even in the view port. I have double checked that hey are under same group objects. Can you please help me to find out what's going on? Thanks

Does hair get special treatment?

Cycles engine.

You can download the blend file here

Visibilities are on as shown below

Image Above

Right Side Render.

Left Side Yellow Particles Emitter in Layer 1.  Group in Layer 2.  Brown Cube Reeds. Golden Seeds. Green Leaves.  Reeds, Seeds, Leaves are part of the emitter.  The [join] mesh command used.

Nail Shaped Hair is the second Particles system of the reed emitter in Layer 2.  The Hair appears as strands in the 3D View Window.

Image Above

Second Emitter complex in layer 2.

Primary

You have already successfully rendered the emitter and the hair particle system.  I have done the same in a new file.  I have not succeeded to render the non hair non emitter.

You could have a finished model with only the group particles hair system present.  The seeds and leaves can be part of the emitter.

For the seed and leaves you can convert them to non particles and be part of the emitter. The particles system can be used to generate the model. Then press the button [convert] in the the modifier panel for the particle system.  The hair particles remain. The emitter is now a complex  of reed, leaves, seed.  Your artistic needs would determine if that is suitable.

You do NOT need to convert hair.  The [convert] of the hair seems to produce edges only which will need to use something like a solidify modifier

Secondary

I used a particle instance modifier ... different from a particle system ... and I could duplicate hair but not object particles.

Tertiary

I will seek a few more alternatives.

Older

Verify your Object Cycles Setting, Cycles Ray Visibility: Camera checkbox is [enabled] for the missing particles.

Verify your particle systems camera render option is TRUE

Under the object Duplication Panel for the missing particles make sure the either None or Frames are selected.  Do not use Verts Faces Groups.

Verify all particles system generate particles for the frame above.

Verify that all materials are created for the render engine.  Cycles Render is compatible with Cycles materials.  Blender Render is compatible with Blender Materials.

Verify that the Render visibility is on for the missing materials.  The camera icon in the outliner panel.

Verify that you have no  transparency in your material.


Converting light emitting objects from Cycles Render to Blender Render After struggling a tiny bit with render durations on some low-lit Cycles scenes, I am trying to convert a Cycles render scene to a Blender internal scene and hopefully, get faster rendering times.

After switching the project to Blender Internal Render, I converted the neon lights that spell the word on the wall, by deleting the material and creating a new material. I increased the Emit value since the neon letters should illuminate the whole scene. And enabled Indirect Lighting in World panel, as well as set Gather to Approximate.

The result is somewhat strange:

1-There are strange artifacts around the emitting objects

2-The letters do not illuminate the scene as they used to in Cycles, unless the objects are mirror/reflection enabled (the bed and the hand are very dark)

3-the glow coming from the light objects only carries onto a small strip of the neighboring walls, which then become dark abruptly, instead of bathing the room in an ambient glow

This is the scene in Cycles, and what I would like the scene to look like (note how the whole room is filled with light yet the glow is soft and casts shadows):

I have looked online and here on SE for render engine conversion tips but couldn't find any...

Blend file:

I did some changes to your scene. The strange artefacts result from the high emit value and the curves themselves.

I adjusted emit value to 15 instead of 1000.
Give the curves some extrusion. No neon light is total flat, it has some depth. A value of 0.001 works great.
I added some ambient occlusion. A value of 0.008 makes the scene less dark but preserves the night mood...


Move material actions separately in NLA for duplicated objects From the starting scene, I keyframed the material of the cube to change intensity 0 -> 1 between frames 1 and 40. I Shift+D-ed that cube to create a new one. I'd like to move the material animation for the second cube to start at a different frame, i.e. go 0 -> 1 between frames 21 and 60.

In NLA I see this:

Both tracks are selected and I cannot select just the one for Cube.001.

I see that I can create a new material (or use Make Single User), but then I would lose the ability to change the material properties (e.g. color) for all objects at once or the ability to tweak the action (e.g. duration) and have it applied to all objects at once.

Is there a way to have linked materials between objects, but manipulate their actions independently in NLA editor?

Blender v2.78 if that matters.

You can't create different animations for same material, because NLA-tracks belong to the material, not to the objects. But there is a walkaround, to make that you want:

You can use one material that will be displayed differently depending on the properties of the object. For example, object index:

Object index sets in object properties. Relations tab:

Then using node setup, like this, you can set different settings for different object using same material.


Is UV mapping and texturing necessary? Can I just use materials before rigging? Brand new to Blender. I've modeled my first character and added materials to give her color. In my research I've found that UV mapping and Texturing is generally the next step. If I'm happy with the coloring that materials gave, can I skip this step and go straight to rigging?
Is UV mapping and texturing just to give it an added sense of realism, since materials give it a cartoony shine?

Thanks,

You don't have to texture a character before you rig it and you don't have to UV unwrap it if a procedural texture works.

While a UV wrapped texture can be used to control the glossy factor in precise parts of the character, you can turn down the overall glossiness of a procedural texture, the steps will depend on which render engine you use and the material you have.

I think it is better to rig a character before unwrapping (especially when learning) as the rigging process can lead to finding bad mesh deforms that need better topology to fix, this leads to an existing UV unwrap needing to be adjusted for the changes.


Keyframe all bones in armature at once? How do I keyframe the location, rotation and scale for all bones in an armature at once?

Select the bones you want to keyframe, then change the mode from Object Mode to Pose Mode.

Then, once you are satisfied with editing your bones, press I and then click on LocRotScale.

This will add a keyframe for the location, rotation and scaling for all selected bones. I suggest you read this.


EEVEE render not using GPU fully I am rendering PNG RGBA frames in EEVEE of a camera fly over a historic building modeled in Blender 2.80.74. PC specs: i7 with 20GB, 1Gb SSD and a GTX 1070 & GTX 1050. EEVEE uses only the GTX 1070. Each Frame takes in total on average 40 seconds to render and write to SSD. During these 40 seconds, the Task manager shows the GTX 1070 is 100% active for roughly 6 seconds and the CPU is 100% active for roughly 10 seconds. Any idea why GPU and/or CPU are not fully used in the 40 seconds and what i can do to reduce render time? See Task Manager output (60 sec charts) below.

Rendering task are more complicated then CPU and GPU usage graph show.

When Blender encounter a bottle neck, sometime it is not the multi-threading task like rendering tiles but a calculation in a single process thread.

And some time because the RAM speed isn't fully catch up with CPU and GPU, or sometime some I/O waiting of hardware is locking the process.

It is hard to tell what is the bottle neck from the scene, especially you just show a task manager image with low resolution. From your graph, the RAM is actually drop for a large amount during the processing. I would guess that Blender is dealing with quite large of detail from your scene, and the thing dealing in Blender is often single python thread which can't not benefit from multi-core CPU.

For speed up the rendering, there are a bunch of option in performance panel, you can try to render single image to see the speed difference.


How to model a wheel (tyre) This is how far I got:

But the tyre is not smooth and has some artifacts on it. If I use more subsurf, it gets more weird.

The steps I took:
The bump map tyre will be of high poly, right? This is what I did:

Make a base mesh with high subsurf.
Model a patch of seamless pattern (this is very hard) and shrinkwrap it to the base mesh. Here it is:

Array it using empty as offset.

More info: https://blenderartists.org/forum/showthread.php?442524-Modeling-a-motorcyle-tyre

Can anyone help in in this regard? I am modeling a wheel for harley davidson sporster.

I also tried the Blenderguru's tutorial. Didn't help as his tutorial aims toward different bump.

I would try using a bevel modifier and add it to the top of the modifier stack. It adds more cuts to the edges giving it a more defined look to the overall shape you may be looking for.


How to flip normals with python in blender game engine? Is there a way to flip or change the normal vector of a face using python in the blender game engine?

This is only possible via Python.

Basically you turn the order of the vertices for each single polygon (face) by exchanging the positions of the first and third vertex

flipping triangles:

flipping quads:

You might need to set the vertex normal too to correct the shading.

Attention:

KX_PolyProxy does not provide the right vertices when the mesh consists of a mix of quads and triangles (Blender 2.73 and earlier). I do not know when this gets fixed.


Glass material is transparent only when object is selected As you can see, I would like to get similar effect in rendering as in material view mode but I'm don't know what could cause the problem. I've used Kitchen_glass material form Archipack standard library and there are two layers of glass on the door and single  layer over screen. Other side is barely visible when rendered and screen light is not visible at all (this is not actual light).

Update

I found out that the shadow from the glass was obscuring inside.
I've turned the "Cast" property off and now I can see through the fist glass, however I cannot see through the second glass when it's sits in the right place:

You might have probably deleted the glass material. So you have to delete your object and add another one.

You can watch the following tutorial
https://youtu.be/p5q_P8WQegQ
https://youtu.be/I685JGTCpCU

Hope it helps.


How to scale a plane to the exact dimensions of a loop cut? I have a plane and a loop cut that is highlighted as shown in the image above. I wanted to know how do I scale the plane to the exact dimensions of the loop cut?

You may do it using a snapping tool.
First select the edge loop in Edit Mode (Alt+RMB) and snap the cursor to it (Shift+S-->Cursor to Selected). Then select the plane in Object Mode and press Shift+S-->Selection to Cursor [Offset]).

Next press the magnet icon to enable the snapping tool and change its type to Vertex. Scale the plane until it snaps to the loopcut's border.

To see the loopcut in Object Mode check the Wire and Draw All Edges checkboxes in Display panel of the Object header.

For irregular planes you can scale along the chosen axes (e.g. S,Y).

You may also snap the plane to the corner of the edge loop in Object Mode. Then change the pivot point type to 3D Cursor, snap the cursor to the corner of the plane in Edit Mode with Shift+S-->Cursor to Selected and then scale it until it fits the edgeloop.


If I make one object with 2 hair particle systems, can I make each particle system on a different layer? If so, how? (blender 2.83) If I make one object with 2 hair particle systems, can I make each particle system on a different layer?  If so, how? (blender 2.83)

never mind, figured it out.
I didn't see the field weights section in the particle settings, that fixed it.


how to make same extrude to other side in object How to make same extrude cut to I did in another side of the same object?

Like this pic here:

There are many ways, tTsure that your object is symmetrical and it's origin is at the center. In the modifier options, choose which axis (x,y, or z) you would like the other extrusion to be.

Hope this helps


Change Base Shapekey without changing the other shapekeys I started adding shapekeys and then noticed I want to edit my basemesh. Unfortunately the changes in the base shapekey affect the other shapekeys. Is it possible to change the base shapekey and not have it affect the other shape keys?

If you edit the basis then it will change all the following shapekeys but to change the other ones without it editing the basis you have to so it in edit mode


Render issue - wrong mesh? As an absolute beginner in Blender 2.8 I modeled a hammer.

Although the mesh looks completely OK to me, it gets ugly in a few places during rendering.

I have 2 questions: 1.) What did I do wrong?  &  2.) How do I fix this?

I would be very happy about your advice.

The complete Model found here: https://drive.google.com/file/d/1VAgxWriZOUKWnnxoGWMVHuRJk8Jojx9M/view?usp=drive_web

The mesh looks TERRIBLE, It contains so many unnecessary vertices, edges, faces. And the faces, NO.

And in the render, you turn the smooth shading on, but in your mesh, the edges, they are probably in flat shading. You don't even get enough bevel edge for the smooth shading, that's a reason for your bad rendering.

You may abused the Boolean tool and accidentally apply it to a high-res mesh. Or you just download, import the mesh from other file format.

There are two way to fix this mess:

Join those unwanted topologies manually
Remesh it by some tool and decimate to a reasonable resolution. (Instant Meshes might be a powerful one)

But the mesh it self isn't that complicated to craft, you might want (and need) to start it over again, with some good topologies.

Here is a good tutorial for this task: Blender Guru - Anvil


Rendering messes up my image but its correct in viewport. please help I was wondering if anyone could help me with a problem I have when rendering in blender.
So my Viewport looks like

But when I render it looks like

If you could please give me some advice on how to fix it I would be very grateful.
Thanks

You have a copy of the donut and the icing in the collection named archive. It's hidden in the viewport only ("eye" icon) but not hidden for rendering. The ojbects are rendered overlapping. That's what you see on the final render.
Uncheck the checkmark of the archive collection in the Outliner and all objects in there are completely hidden in the viewport and rendering in Blender 2.9x.
(Blender 2.8x users must disable the rendering with a Restriction Toggle as shown here: Image Texture completely washed out in Render, but not in Viewport Shading)


Is it possible to color-code the tabs on the toolshelf? One thing I've been wanting to do is color-code the tabs on Blender's toolshelf, either with an existing addon somewhere, or by myself in Python. There are so many great addons going on the T-panel that I can't read what's on the tabs anymore.

Ideally putting an icon on a tab, or at the very least making each a different color, would help a lot. If there isn't an addon, can I do within Blender's Python?

My knowledge of Blender's Python API isn't great but is improving. I'd definitely make this a goal but I'd like to know first if it's even possible.

In blender's preferences for the 3DView theme settings, almost at the bottom, you will find the colours used for drawing the tabs.

This is a global property that is used by every tab and the only way blender offers to alter the tab panel colouring. You could adjust your theme so that the Tab Active and Tab Inactive colours are lighter so that there is more contrast with the text to make them easier to read.

In general blender doesn't offer ways to adjust the UI as far as colours go, almost every colour used is defined within a theme so that the UI stays consistant.


While texture painting, is there a way to limit the maximum opacity of the paint simmilar to the weight setting in weight paint mode I am using a mouse to do try and paint an area, I have to zoom in on the area to be able to get the precision I need however as I have to move the camera multiple times to cover the whole area I can't paint in a single stroke and I Can't find a way to prevent the paint from different strokes from stacking creating darker patches of paint where the strokes meet. Is there a setting like the weight slider in weight painting mode that simply limits the maximum strength of the paint or some other way to prevent dark edges between strokes

Example:

Intended result:

The answer is that no, you cannot set a threshold that will limit the full opacity of overlapping strokes - these strokes from your example are additive, so the overlapping area appears more opaque than the parts that do not intersect.

The better way to handle this is to use the Mask tool to paint your strokes using the visualization color of your choice and setting your strength to full with no pressure control, then inverting the mask and switching to the Fill tool and setting the strength to your desired transparency, and then you can get even fill across your whole mask.


Export FBX with shape keys and animations takes FOREVER? Ok, I am following https://www.youtube.com/watch?v=1Zqy5GhUV-Q just trying to export my skapekeys/animations in FBX from Blender (going to Unity).

Granted my mesh has a lot of parts and I had total 6 animations, but it has been loading for the past 2 min now. Did I do something wrong? I'm on a Mac and blender 2.79, cycles.

How can I reduce this export time? Im not even sure it's going through at this point.

Try 'Selected Objects only' - on my machine, Blender hangs for tens of minutes if this isn't selected as it tries to export every object's animation for every object recursively.


"Apply modifiers" button not appearing? I am attempting to follow a youtube tutorial for decimating a model - I need to do this for a continuous LOD in a game I am creating.

However, in the tutorial, he uses some "Apply modifiers" button, which I can't find anywhere!

If I start up blender with the default box, I see it, but when I open a .blend, or import a model, the button disappears!

Screenshot:

What am I doing wrong here?

The apply modifier button will be on the modifier.
Blender 2.9x
In Blender 2.9x click on the top triangle to apply the modifier, or use Ctrl+A.

See: How to apply a modifier in V2.9+
Blender 2.7x

You have to be in object mode to apply modifiers. Applying the  modifier does not work on multiple selections, only the active object gets applied.