# <hr>Calculates the tangents and bitangents for the imported meshes. 
#
# Does nothing if a mesh does not have normals. You might want this post 
# processing step to be executed if you plan to use tangent space calculations 
# such as normal mapping  applied to the meshes. There's a config setting,
# <tt>#AI_CONFIG_PP_CT_MAX_SMOOTHING_ANGLE<tt>, which allows you to specify
# a maximum smoothing angle for the algorithm. However, usually you'll
# want to leave it at the default value.
#
aiProcess_CalcTangentSpace = 0x1

## <hr>Identifies and joins identical vertex data sets within all 
#  imported meshes. 
# 
# After this step is run, each mesh contains unique vertices,
# so a vertex may be used by multiple faces. You usually want
# to use this post processing step. If your application deals with
# indexed geometry, this step is compulsory or you'll just waste rendering
# time. <b>If this flag is not specified<b>, no vertices are referenced by
# more than one face and <b>no index buffer is required<b> for rendering.
#
aiProcess_JoinIdenticalVertices = 0x2

## <hr>Converts all the imported data to a left-handed coordinate space. 
#
# By default the data is returned in a right-handed coordinate space (which 
# OpenGL prefers). In this space, +X points to the right, 
# +Z points towards the viewer, and +Y points upwards. In the DirectX 
# coordinate space +X points to the right, +Y points upwards, and +Z points 
# away from the viewer.
#
# You'll probably want to consider this flag if you use Direct3D for
# rendering. The #aiProcess_ConvertToLeftHanded flag supersedes this
# setting and bundles all conversions typically required for D3D-based
# applications.
#
aiProcess_MakeLeftHanded = 0x4

## <hr>Triangulates all faces of all meshes. 
#
# By default the imported mesh data might contain faces with more than 3
# indices. For rendering you'll usually want all faces to be triangles. 
# This post processing step splits up faces with more than 3 indices into 
# triangles. Line and point primitives are #not# modified! If you want
# 'triangles only' with no other kinds of primitives, try the following
# solution:
# <ul>
# <li>Specify both #aiProcess_Triangulate and #aiProcess_SortByPType <li>
# <li>Ignore all point and line meshes when you process assimp's output<li>
# <ul>
#
aiProcess_Triangulate = 0x8

## <hr>Removes some parts of the data structure (animations, materials, 
#  light sources, cameras, textures, vertex components).
#
# The  components to be removed are specified in a separate
# configuration option, <tt>#AI_CONFIG_PP_RVC_FLAGS<tt>. This is quite useful
# if you don't need all parts of the output structure. Vertex colors
# are rarely used today for example... Calling this step to remove unneeded
# data from the pipeline as early as possible results in increased 
# performance and a more optimized output data structure.
# This step is also useful if you want to force Assimp to recompute 
# normals or tangents. The corresponding steps don't recompute them if 
# they're already there (loaded from the source asset). By using this 
# step you can make sure they are NOT there.
#
# This flag is a poor one, mainly because its purpose is usually
# misunderstood. Consider the following case: a 3D model has been exported
# from a CAD app, and it has per-face vertex colors. Vertex positions can't be
# shared, thus the #aiProcess_JoinIdenticalVertices step fails to
# optimize the data because of these nasty little vertex colors.
# Most apps don't even process them, so it's all for nothing. By using
# this step, unneeded components are excluded as early as possible
# thus opening more room for internal optimizations. 
#
aiProcess_RemoveComponent = 0x10

## <hr>Generates normals for all faces of all meshes. 
#
# This is ignored if normals are already there at the time this flag 
# is evaluated. Model importers try to load them from the source file, so
# they're usually already there. Face normals are shared between all points
# of a single face, so a single point can have multiple normals, which
# forces the library to duplicate vertices in some cases.
# #aiProcess_JoinIdenticalVertices is #senseless# then.
#
# This flag may not be specified together with #aiProcess_GenSmoothNormals.
#
aiProcess_GenNormals = 0x20

## <hr>Generates smooth normals for all vertices in the mesh.
#
# This is ignored if normals are already there at the time this flag 
# is evaluated. Model importers try to load them from the source file, so
# they're usually already there. 
#
# This flag may not be specified together with 
# #aiProcess_GenNormals. There's a configuration option, 
# <tt>#AI_CONFIG_PP_GSN_MAX_SMOOTHING_ANGLE<tt> which allows you to specify
# an angle maximum for the normal smoothing algorithm. Normals exceeding
# this limit are not smoothed, resulting in a 'hard' seam between two faces.
# Using a decent angle here (e.g. 80 degrees) results in very good visual
# appearance.
#
aiProcess_GenSmoothNormals = 0x40

## <hr>Splits large meshes into smaller sub-meshes.
#
# This is quite useful for real-time rendering, where the number of triangles
# which can be maximally processed in a single draw-call is limited 
# by the video driverhardware. The maximum vertex buffer is usually limited
# too. Both requirements can be met with this step: you may specify both a 
# triangle and vertex limit for a single mesh.
#
# The split limits can (and should!) be set through the 
# <tt>#AI_CONFIG_PP_SLM_VERTEX_LIMIT<tt> and <tt>#AI_CONFIG_PP_SLM_TRIANGLE_LIMIT<tt> 
# settings. The default values are <tt>#AI_SLM_DEFAULT_MAX_VERTICES<tt> and 
# <tt>#AI_SLM_DEFAULT_MAX_TRIANGLES<tt>. 
#
# Note that splitting is generally a time-consuming task, but only if there's
# something to split. The use of this step is recommended for most users.
#
aiProcess_SplitLargeMeshes = 0x80

## <hr>Removes the node graph and pre-transforms all vertices with
# the local transformation matrices of their nodes.
#
# The output scene still contains nodes, however there is only a
# root node with children, each one referencing only one mesh,
# and each mesh referencing one material. For rendering, you can
# simply render all meshes in order - you don't need to pay
# attention to local transformations and the node hierarchy.
# Animations are removed during this step.
# This step is intended for applications without a scenegraph.
# The step CAN cause some problems: if e.g. a mesh of the asset
# contains normals and another, using the same material index, does not, 
# they will be brought together, but the first meshes's part of
# the normal list is zeroed. However, these artifacts are rare.
# @note The <tt>#AI_CONFIG_PP_PTV_NORMALIZE<tt> configuration property
# can be set to normalize the scene's spatial dimension to the -1...1
# range. 
#
aiProcess_PreTransformVertices = 0x100

## <hr>Limits the number of bones simultaneously affecting a single vertex
#  to a maximum value.
#
# If any vertex is affected by more than the maximum number of bones, the least 
# important vertex weights are removed and the remaining vertex weights are
# renormalized so that the weights still sum up to 1.
# The default bone weight limit is 4 (defined as <tt>#AI_LMW_MAX_WEIGHTS<tt> in
# config.h), but you can use the <tt>#AI_CONFIG_PP_LBW_MAX_WEIGHTS<tt> setting to
# supply your own limit to the post processing step.
#
# If you intend to perform the skinning in hardware, this post processing 
# step might be of interest to you.
#
aiProcess_LimitBoneWeights = 0x200

## <hr>Validates the imported scene data structure.
# This makes sure that all indices are valid, all animations and
# bones are linked correctly, all material references are correct .. etc.
#
# It is recommended that you capture Assimp's log output if you use this flag,
# so you can easily find out what's wrong if a file fails the
# validation. The validator is quite strict and will find #all#
# inconsistencies in the data structure... It is recommended that plugin 
# developers use it to debug their loaders. There are two types of
# validation failures:
# <ul>
# <li>Error: There's something wrong with the imported data. Further
#   postprocessing is not possible and the data is not usable at all.
#   to the log file, <tt>#AI_SCENE_FLAGS_VALIDATION_WARNING<tt> is set
#   in #aiScene::mFlags<li>
# <ul>
#
# This post-processing step is not time-consuming. Its use is not
# compulsory, but recommended. 
#
aiProcess_ValidateDataStructure = 0x400

## <hr>Reorders triangles for better vertex cache locality.
#
# The step tries to improve the ACMR (average post-transform vertex cache
# miss ratio) for all meshes. The implementation runs in O(n) and is 
# roughly based on the 'tipsify' algorithm (see <a href="
# http:www.cs.princeton.edugfxpubsSander_2007_%3ETRtipsy.pdf">this
# paper<a>).
#
# If you intend to render huge models in hardware, this step might
# be of interest to you. The <tt>#AI_CONFIG_PP_ICL_PTCACHE_SIZE<tt>config
# setting can be used to fine-tune the cache optimization.
#
aiProcess_ImproveCacheLocality = 0x800

## <hr>Searches for redundantunreferenced materials and removes them.
#
# This is especially useful in combination with the 
# #aiProcess_PretransformVertices and #aiProcess_OptimizeMeshes flags. 
# Both join small meshes with equal characteristics, but they can't do 
# their work if two meshes have different materials. Because several
# material settings are lost during Assimp's import filters,
# (and because many exporters don't check for redundant materials), huge
# models often have materials which are are defined several times with
# exactly the same settings.
#
# Several material settings not contributing to the final appearance of
# a surface are ignored in all comparisons (e.g. the material name).
# So, if you're passing additional information through the
# content pipeline (probably using #magic# material names), don't 
# specify this flag. Alternatively take a look at the
# <tt>#AI_CONFIG_PP_RRM_EXCLUDE_LIST<tt> setting.
# 
aiProcess_RemoveRedundantMaterials = 0x1000

## <hr>This step tries to determine which meshes have normal vectors 
# that are facing inwards and inverts them.
#
# The algorithm is simple but effective:
# the bounding box of all vertices + their normals is compared against
# the volume of the bounding box of all vertices without their normals.
# This works well for most objects, problems might occur with planar
# surfaces. However, the step tries to filter such cases.
# The step inverts all in-facing normals. Generally it is recommended
# to enable this step, although the result is not always correct.
#
aiProcess_FixInfacingNormals = 0x2000

## <hr>This step splits meshes with more than one primitive type in 
#  homogeneous sub-meshes. 
#
#  The step is executed after the triangulation step. After the step
#  returns, just one bit is set in aiMesh::mPrimitiveTypes. This is 
#  especially useful for real-time rendering where point and line
#  primitives are often ignored or rendered separately.
#  You can use the <tt>#AI_CONFIG_PP_SBP_REMOVE<tt> option to specify which
#  primitive types you need. This can be used to easily exclude
#  lines and points, which are rarely used, from the import.
#
aiProcess_SortByPType = 0x8000

## <hr>This step searches all meshes for degenerate primitives and
#  converts them to proper lines or points.
#
# A face is 'degenerate' if one or more of its points are identical.
# To have the degenerate stuff not only detected and collapsed but
# removed, try one of the following procedures:
# <br><b>1.<b> (if you support lines and points for rendering but don't
#    want the degenerates)<br>
# <ul>
#   <li>Specify the #aiProcess_FindDegenerates flag.
#   <li>
#   <li>Set the <tt>AI_CONFIG_PP_FD_REMOVE<tt> option to 1. This will 
#       cause the step to remove degenerate triangles from the import
#       as soon as they're detected. They won't pass any further
#       pipeline steps.
#   <li>
# <ul>
# <br><b>2.<b>(if you don't support lines and points at all)<br>
# <ul>
#   <li>Specify the #aiProcess_FindDegenerates flag.
#   <li>
#   <li>Specify the #aiProcess_SortByPType flag. This moves line and
#     point primitives to separate meshes.
#   <li>
#   <li>Set the <tt>AI_CONFIG_PP_SBP_REMOVE<tt> option to 
#       @code aiPrimitiveType_POINTS | aiPrimitiveType_LINES
#       @endcode to cause SortByPType to reject point
#       and line meshes from the scene.
#   <li>
# <ul>
# @note Degenerate polygons are not necessarily evil and that's why
# they're not removed by default. There are several file formats which 
# don't support lines or points, and some exporters bypass the
# format specification and write them as degenerate triangles instead.
#
aiProcess_FindDegenerates = 0x10000

## <hr>This step searches all meshes for invalid data, such as zeroed
#  normal vectors or invalid UV coords and removesfixes them. This is
#  intended to get rid of some common exporter errors.
#
# This is especially useful for normals. If they are invalid, and
# the step recognizes this, they will be removed and can later
# be recomputed, i.e. by the #aiProcess_GenSmoothNormals flag.<br>
# The step will also remove meshes that are infinitely small and reduce
# animation tracks consisting of hundreds if redundant keys to a single
# key. The <tt>AI_CONFIG_PP_FID_ANIM_ACCURACY<tt> config property decides
# the accuracy of the check for duplicate animation tracks.
#
aiProcess_FindInvalidData = 0x20000

## <hr>This step converts non-UV mappings (such as spherical or
#  cylindrical mapping) to proper texture coordinate channels.
#
# Most applications will support UV mapping only, so you will
# probably want to specify this step in every case. Note that Assimp is not
# always able to match the original mapping implementation of the 
# 3D app which produced a model perfectly. It's always better to let the
# modelling app compute the UV channels - 3ds max, Maya, Blender, 
# LightWave, and Modo do this for example.
#
# @note If this step is not requested, you'll need to process the
# <tt>#AI_MATKEY_MAPPING<tt> material property in order to display all assets
# properly.
#
aiProcess_GenUVCoords = 0x40000

## <hr>This step applies per-texture UV transformations and bakes
#  them into stand-alone vtexture coordinate channels.
#  
# UV transformations are specified per-texture - see the 
# <tt>#AI_MATKEY_UVTRANSFORM<tt> material key for more information. 
# This step processes all textures with 
# transformed input UV coordinates and generates a new (pre-transformed) UV channel 
# which replaces the old channel. Most applications won't support UV 
# transformations, so you will probably want to specify this step.
#
# @note UV transformations are usually implemented in real-time apps by 
# transforming texture coordinates at vertex shader stage with a 3x3
# (homogenous) transformation matrix.
#
aiProcess_TransformUVCoords = 0x80000

## <hr>This step searches for duplicate meshes and replaces them
#  with references to the first mesh.
#
#  This step takes a while, so don't use it if speed is a concern.
#  Its main purpose is to workaround the fact that many export
#  file formats don't support instanced meshes, so exporters need to
#  duplicate meshes. This step removes the duplicates again. Please 
#  note that Assimp does not currently support per-node material
#  assignment to meshes, which means that identical meshes with
#  different materials are currently #not# joined, although this is 
#  planned for future versions.
#
aiProcess_FindInstances = 0x100000

## <hr>A postprocessing step to reduce the number of meshes.
#
#  This will, in fact, reduce the number of draw calls.
#
#  This is a very effective optimization and is recommended to be used
#  together with #aiProcess_OptimizeGraph, if possible. The flag is fully
#  compatible with both #aiProcess_SplitLargeMeshes and #aiProcess_SortByPType.
#
aiProcess_OptimizeMeshes  = 0x200000


## <hr>A postprocessing step to optimize the scene hierarchy. 
#
#  Nodes without animations, bones, lights or cameras assigned are 
#  collapsed and joined.
#
#  Node names can be lost during this step. If you use special 'tag nodes'
#  to pass additional information through your content pipeline, use the
#  <tt>#AI_CONFIG_PP_OG_EXCLUDE_LIST<tt> setting to specify a list of node 
#  names you want to be kept. Nodes matching one of the names in this list won't
#  be touched or modified.
#
#  Use this flag with caution. Most simple files will be collapsed to a 
#  single node, so complex hierarchies are usually completely lost. This is not
#  useful for editor environments, but probably a very effective
#  optimization if you just want to get the model data, convert it to your
#  own format, and render it as fast as possible. 
#
#  This flag is designed to be used with #aiProcess_OptimizeMeshes for best
#  results.
#
#  @note 'Crappy' scenes with thousands of extremely small meshes packed
#  in deeply nested nodes exist for almost all file formats.
#  #aiProcess_OptimizeMeshes in combination with #aiProcess_OptimizeGraph 
#  usually fixes them all and makes them renderable. 
#
aiProcess_OptimizeGraph  = 0x400000

## <hr>This step flips all UV coordinates along the y-axis and adjusts
# material settings and bitangents accordingly.
#
# <b>Output UV coordinate system:<b>
# @code
# 0y|0y ---------- 1x|0y 
# |                 |
# |                 |
# |                 |
# 0x|1y ---------- 1x|1y
# @endcode
#
# You'll probably want to consider this flag if you use Direct3D for
# rendering. The #aiProcess_ConvertToLeftHanded flag supersedes this
# setting and bundles all conversions typically required for D3D-based
# applications.
#
aiProcess_FlipUVs = 0x800000

## <hr>This step adjusts the output face winding order to be CW.
#
# The default face winding order is counter clockwise (CCW).
#
# <b>Output face order:<b>
# @code
#       x2
#           
#                         x0
#  x1
# @endcode
#
aiProcess_FlipWindingOrder  = 0x1000000

## <hr>This step splits meshes with many bones into sub-meshes so that each
# su-bmesh has fewer or as many bones as a given limit. 
#
aiProcess_SplitByBoneCount  = 0x2000000

## <hr>This step removes bones losslessly or according to some threshold.
#
#  In some cases (i.e. formats that require it) exporters are forced to
#  assign dummy bone weights to otherwise static meshes assigned to
#  animated meshes. Full, weight-based skinning is expensive while
#  animating nodes is extremely cheap, so this step is offered to clean up
#  the data in that regard. 
#                                                              
#  Use <tt>#AI_CONFIG_PP_DB_THRESHOLD<tt> to control this. 
#  Use <tt>#AI_CONFIG_PP_DB_ALL_OR_NONE<tt> if you want bones removed if and 
#  only if all bones within the scene qualify for removal.
#
aiProcess_Debone  = 0x4000000

aiProcess_GenEntityMeshes = 0x100000
aiProcess_OptimizeAnimations = 0x200000
aiProcess_FixTexturePaths = 0x200000

## @def aiProcess_ConvertToLeftHanded
 #  @brief Shortcut flag for Direct3D-based applications. 
 #
 #  Supersedes the #aiProcess_MakeLeftHanded and #aiProcess_FlipUVs and
 #  #aiProcess_FlipWindingOrder flags.
 #  The output data matches Direct3D's conventions: left-handed geometry, upper-left
 #  origin for UV coordinates and finally clockwise face order, suitable for CCW culling.
 #
 #  @deprecated 
 #
aiProcess_ConvertToLeftHanded = ( \
    aiProcess_MakeLeftHanded     | \
    aiProcess_FlipUVs            | \
    aiProcess_FlipWindingOrder   | \
    0 ) 


## @def aiProcessPreset_TargetRealtimeUse_Fast
 #  @brief Default postprocess configuration optimizing the data for real-time rendering.
 #  
 #  Applications would want to use this preset to load models on end-user PCs,
 #  maybe for direct use in game.
 #
 # If you're using DirectX, don't forget to combine this value with
 # the #aiProcess_ConvertToLeftHanded step. If you don't support UV transformations
 # in your application apply the #aiProcess_TransformUVCoords step, too.
 #  @note Please take the time to read the docs for the steps enabled by this preset. 
 #  Some of them offer further configurable properties, while some of them might not be of
 #  use for you so it might be better to not specify them.
 #
aiProcessPreset_TargetRealtime_Fast = ( \
    aiProcess_CalcTangentSpace      |  \
    aiProcess_GenNormals            |  \
    aiProcess_JoinIdenticalVertices |  \
    aiProcess_Triangulate           |  \
    aiProcess_GenUVCoords           |  \
    aiProcess_SortByPType           |  \
    0 )

 ## @def aiProcessPreset_TargetRealtime_Quality
  #  @brief Default postprocess configuration optimizing the data for real-time rendering.
  #
  #  Unlike #aiProcessPreset_TargetRealtime_Fast, this configuration
  #  performs some extra optimizations to improve rendering speed and
  #  to minimize memory usage. It could be a good choice for a level editor
  #  environment where import speed is not so important.
  #  
  #  If you're using DirectX, don't forget to combine this value with
  #  the #aiProcess_ConvertToLeftHanded step. If you don't support UV transformations
  #  in your application apply the #aiProcess_TransformUVCoords step, too.
  #  @note Please take the time to read the docs for the steps enabled by this preset. 
  #  Some of them offer further configurable properties, while some of them might not be
  #  of use for you so it might be better to not specify them.
  #
aiProcessPreset_TargetRealtime_Quality = ( \
    aiProcess_CalcTangentSpace              |  \
    aiProcess_GenSmoothNormals              |  \
    aiProcess_JoinIdenticalVertices         |  \
    aiProcess_ImproveCacheLocality          |  \
    aiProcess_LimitBoneWeights              |  \
    aiProcess_RemoveRedundantMaterials      |  \
    aiProcess_SplitLargeMeshes              |  \
    aiProcess_Triangulate                   |  \
    aiProcess_GenUVCoords                   |  \
    aiProcess_SortByPType                   |  \
    aiProcess_FindDegenerates               |  \
    aiProcess_FindInvalidData               |  \
    0 )

 ## @def aiProcessPreset_TargetRealtime_MaxQuality
  #  @brief Default postprocess configuration optimizing the data for real-time rendering.
  #
  #  This preset enables almost every optimization step to achieve perfectly
  #  optimized data. It's your choice for level editor environments where import speed 
  #  is not important.
  #  
  #  If you're using DirectX, don't forget to combine this value with
  #  the #aiProcess_ConvertToLeftHanded step. If you don't support UV transformations
  #  in your application, apply the #aiProcess_TransformUVCoords step, too.
  #  @note Please take the time to read the docs for the steps enabled by this preset. 
  #  Some of them offer further configurable properties, while some of them might not be
  #  of use for you so it might be better to not specify them.
  #
aiProcessPreset_TargetRealtime_MaxQuality = ( \
    aiProcessPreset_TargetRealtime_Quality   |  \
    aiProcess_FindInstances                  |  \
    aiProcess_ValidateDataStructure          |  \
    aiProcess_OptimizeMeshes                 |  \
    0 )
#   The import fails. #Importer::GetErrorString() or #aiGetErrorString()
#   carry the error message around.<li>
# <li>Warning: There are some minor issues (e.g. 1000000 animation 
#   keyframes with the same time), but further postprocessing and use
#   of the data structure is still safe. Warning details are written