de61cfe7c5
Better materials: - default values will no longer trigger things like emission, clear coat being enabled etc incorrectly, mostly importers misunderstand this value, a value of 1 is not actually enabled emission, it must have a non zero setting other than emission value for the emission flags to actually be enabled correctly in our engine #42386 - lambert materials are warned against significantly, do not use Lambert in Godot, use a PBR material like Ai Standard Surface (it's like going from low quality to high definition in terms of output in scenes and on assets) - roughness values are calculated correctly in this version Fixes for normal's array - some normal's from some files were dropped and generated, this is now fixed. - FBX indexing for items with (-1) index, for normal data is supported, this is super helpful at increasing our range of compatibility of FBX meshes. Fix bone rest data **no longer requiring go to bind pose in Maya and various applications** - Partial fix for #43688 Validation tools added for validating large projects Provide package name, vendor and FBX vendor in the log. Implemented metadata properties so we can read extra document info required for bug reporting **FBX 2011 (version 7200)** is unsupported now, you must re-export your file in Maya or Max to upgrade the file format. Fixes skin bind poses being generated based on node xforms in the scene Fixes duplicate bones being added to skin and prevents add_bones from registering skeleton bones it now registers skin bind poses, but this should really be documented in the engine correctly right now it doesn't tell you this is the case. |
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.. | ||
data | ||
doc_classes | ||
fbx_parser | ||
tools | ||
config.py | ||
editor_scene_importer_fbx.cpp | ||
editor_scene_importer_fbx.h | ||
readme.md | ||
register_types.cpp | ||
register_types.h | ||
SCsub |
Open Source FBX Specification for the Importer
The goal of this document is to make everything in FBX clearly stated, any errors will be corrected over time this is a first draft.
fbx parser - originally from assimp
- Folder: /modules/fbx/fbx_parser
- Upstream: assimp
- Original Version: git (308db73d0b3c2d1870cd3e465eaa283692a4cf23, 2019)
- License: BSD-3-Clause
This can never be updated from upstream, we have heavily modified the parser to provide memory safety and add some functionality. If anything we should give this parser back to assimp at some point as it has a lot of new features.
Updating assimp fbx parser
Don't. it's not possible the code is rewritten in many areas to remove thirdparty deps and various bugs are fixed.
Many days were put into rewriting the parser to use safe code and safe memory accessors.
File Headers
FBX Binaries start with the header "Kaydara FBX Binary"
FBX ASCII documents contain a larger header, sometimes with copyright information for a file.
Detecting these is pretty simple.
What is an OP link?
It's an object to property link. It lists the properties for that object in some cases. Source and destination based by ID.
What is a OO link?
Its an object to object link, it contains the ID source and destination ID.
FBX Node connections
Nodes in FBX are connected using OO links, This means Object to Object.
FBX has a single other kind of link which is Object Property, this is used for Object to Property Links, this can be extra attributes, defaults, or even some simple settings.
Bones / Joints / Locators
Bones in FBX are nodes, they initially have the Model:: Type, then have links to SubDeformer the sub deformer is part of the skin there is also an explicit Skin link, which then links to the geometry using OO links in the document.
Rotation Order in FBX compared to Godot
Godot uses the rotation order: YXZ
FBX has dynamic rotation order to prevent gimbal lock with complex animations
enum RotOrder {
RotOrder_EulerXYZ = 0
RotOrder_EulerXZY,
RotOrder_EulerYZX,
RotOrder_EulerYXZ,
RotOrder_EulerZXY,
RotOrder_EulerZYX,
RotOrder_SphericXYZ // nobody uses this - as far as we can tell
};
Pivot transforms
Pivot description:
- Maya and 3DS max consider everything to be in node space (bones joints, skins, lights, cameras, etc)
- Everything is a node, this means essentially nodes are auto or variants
- They are local to the node in the tree.
- They are used to calculate where a node is in space
// For a better reference you can check editor_scene_importer_fbx.h
// references: GenFBXTransform / read the data in
// references: ComputePivotTransform / run the calculation
// This is the local pivot transform for the node, not the global transforms
Transform ComputePivotTransform(
Transform chain[TransformationComp_MAXIMUM],
Transform &geometric_transform) {
// Maya pivots
Transform T = chain[TransformationComp_Translation];
Transform Roff = chain[TransformationComp_RotationOffset];
Transform Rp = chain[TransformationComp_RotationPivot];
Transform Rpre = chain[TransformationComp_PreRotation];
Transform R = chain[TransformationComp_Rotation];
Transform Rpost = chain[TransformationComp_PostRotation];
Transform Soff = chain[TransformationComp_ScalingOffset];
Transform Sp = chain[TransformationComp_ScalingPivot];
Transform S = chain[TransformationComp_Scaling];
// 3DS Max Pivots
Transform OT = chain[TransformationComp_GeometricTranslation];
Transform OR = chain[TransformationComp_GeometricRotation];
Transform OS = chain[TransformationComp_GeometricScaling];
// Calculate 3DS max pivot transform - use geometric space (e.g doesn't effect children nodes only the current node)
geometric_transform = OT * OR * OS;
// Calculate standard maya pivots
return T * Roff * Rp * Rpre * R * Rpost.inverse() * Rp.inverse() * Soff * Sp * S * Sp.inverse();
}
Transform inheritance for FBX Nodes
The goal of below is to explain why they implement this in the first place.
The use case is to make nodes have an option to override their local scaling or to make scaling influenced by orientation, which i would imagine would be useful for when you need to rotate a node and the child to scale based on the orientation rather than setting on the rotation matrix planes.
// not modified the formatting here since this code must remain clear
enum TransformInheritance {
Transform_RrSs = 0,
// Parent Rotation * Local Rotation * Parent Scale * Local Scale -- Parent Rotation Offset * Parent ScalingOffset (Local scaling is offset by rotation of parent node)
Transform_RSrs = 1, // Parent Rotation * Parent Scale * Local Rotation * Local Scale -- Parent * Local (normal mode)
Transform_Rrs = 2, // Parent Rotation * Local Rotation * Local Scale -- Node transform scale is the only relevant component
TransformInheritance_MAX // end-of-enum sentinel
};
enum TransformInheritance {
Transform_RrSs = 0,
// Local scaling is offset by rotation of parent node
Transform_RSrs = 1,
// Parent * Local (normal mode)
Transform_Rrs = 2,
// Node transform scale is the only relevant component
TransformInheritance_MAX // end-of-enum sentinel
};
Axis in FBX
Godot has one format for the declared axis
AXIS X, AXIS Y, -AXIS Z
FBX supports any format you can think of. As it has to support Maya and 3DS Max.
FBX File Header
GlobalSettings: {
Version: 1000
Properties70: {
P: "UpAxis", "int", "Integer", "",1
P: "UpAxisSign", "int", "Integer", "",1
P: "FrontAxis", "int", "Integer", "",2
P: "FrontAxisSign", "int", "Integer", "",1
P: "CoordAxis", "int", "Integer", "",0
P: "CoordAxisSign", "int", "Integer", "",1
P: "OriginalUpAxis", "int", "Integer", "",1
P: "OriginalUpAxisSign", "int", "Integer", "",1
P: "UnitScaleFactor", "double", "Number", "",1
P: "OriginalUnitScaleFactor", "double", "Number", "",1
P: "AmbientColor", "ColorRGB", "Color", "",0,0,0
P: "DefaultCamera", "KString", "", "", "Producer Perspective"
P: "TimeMode", "enum", "", "",6
P: "TimeProtocol", "enum", "", "",2
P: "SnapOnFrameMode", "enum", "", "",0
P: "TimeSpanStart", "KTime", "Time", "",0
P: "TimeSpanStop", "KTime", "Time", "",92372316000
P: "CustomFrameRate", "double", "Number", "",-1
P: "TimeMarker", "Compound", "", ""
P: "CurrentTimeMarker", "int", "Integer", "",-1
}
}
FBX FILE declares axis dynamically using FBX header
Coord is X Up is Y Front is Z
GODOT - constant reference point
Coord is X positive, Y is up positive, Front is -Z negative
Explaining MeshGeometry indexing
Reference type declared:
- Direct (directly related to the mapping information type)
- IndexToDirect (Map with key value, meaning depends on the MappingInformationType)
ControlPoint is a vertex
- None The mapping is undetermined.
- ByVertex There will be one mapping coordinate for each surface control point/vertex.
- If you have direct reference type vertices [x]
- If you have IndexToDirect reference type the UV
- ByPolygonVertex There will be one mapping coordinate for each vertex, for every polygon of which it is a part. This means that a vertex will have as many mapping coordinates as polygons of which it is a part. (Sorted by polygon, referencing vertex)
- ByPolygon There can be only one mapping coordinate for the whole polygon.
- One mapping per polygon polygon x has this normal x
- For each vertex of the polygon then set the normal to x
- ByEdge There will be one mapping coordinate for each unique edge in the mesh. This is meant to be used with smoothing layer elements. (Mapping is referencing the edge id)
- AllSame There can be only one mapping coordinate for the whole surface.