This is an extension for glTFRuntime (https://github.com/rdeioris/glTFRuntime) adding support for FBX assets.
Currently the following features are supported:
- Static Meshes
- Hierarchies
- Skeletal Meshes with unlimited influences
- Morph Targets
- Skeletal Animations (with or without Mesh specified in the asset)
- MorphTarget Animations
- Vertex Colors
- PBR Material (still far from perfect)
Work in progress:
- LOD Groups
- Cameras
- Lights
- Async functions
- Improved material handling
- Raw curves extraction
- Animation retargeting
- Load StaticMeshes as Skeletal (for supporting MorphTargets without a Skeleton)
This plugin makes use of the amazing ufbx (https://github.com/ufbx/ufbx) library for the parsing.
- You need an Unreal C++ project (otherwise you will not be able to compile this plugin).
- You need glTFRuntime enabled in your project (at least version 20240427)
- Clone the master branch of this repository in the Plugins/ directory of your project
- Regenerate the solution
- Enjoy!
The easiest way is to use the provided Actor, glTFRuntimeFBXAssetActor that contains the logic for building a scene by iterating the nodes as well as playing animations.
The Actor expects a glTFRuntimeAsset as input. Those objects can be generated by the various glTFRuntime loaders (File, URLs, strings, commands, clipboard...) but requires the 'Blob' mode (that disables the GLTF parsing):
As with other glTFRuntime extensions, the loaders can process FBX files compressed as gzip, lz4 or as zip archives (generally the most common way if you want to bundle the external textures in a single file).
Currently loading textures from external files is not supported for security reasons (The FBX format has a weird/risky way of dealing with textures paths...)
Once you have the glTFRuntimeAsset object, you can pass it to a standard Spawn Actor From Class node (or the World->SpawnActor C++ method):
For more advanced users lower-level functions as provided in a Blueprint Function Library: UglTFRuntimeFBXFunctionLibrary
The glTFRuntimeFBXAssetActor uses those functions to implement its whole logic.
There are two main 'Objects' (well, actually they are Structs) to deal with:
- FBXNode (FglTFRuntimeFBXNode): represents a node in the FBX asset, it is the basic block for the hiearchy (nodes can be plain transforms/locators, meshes, skeletons, bones, cameras, lights...). It exposes a name.
- FBXAnim (FglTFRuntimeFBXAnim): represents an animation, multiple animations can be exposed in the same asset. It exposes a name and the duration of the animation (in seconds).
static FglTFRuntimeFBXNode GetFBXRootNode(UglTFRuntimeAsset* Asset);Returns the so called "root node" (the initial node in the tree from which you can start iterating the graph)
static TArray<FglTFRuntimeFBXNode> GetFBXNodes(UglTFRuntimeAsset* Asset);Returns all of the nodes in the asset.
static TArray<FglTFRuntimeFBXNode> GetFBXNodesMeshes(UglTFRuntimeAsset* Asset);Returns all of the nodes containing a mesh.
static TArray<FglTFRuntimeFBXNode> GetFBXNodeChildren(UglTFRuntimeAsset* Asset, const FglTFRuntimeFBXNode& FBXNode);Get the children of a node.
static TArray<FglTFRuntimeFBXAnim> GetFBXAnimations(UglTFRuntimeAsset* Asset);Returns all the animations in the asset.
static bool GetFBXDefaultAnimation(UglTFRuntimeAsset* Asset, FglTFRuntimeFBXAnim& FBXAnim);An asset can specify a default animation. If available this function will return it in the FBXAnim parameter. (otherwise it returns 'false')
static bool IsFBXNodeBone(UglTFRuntimeAsset* Asset, const FglTFRuntimeFBXNode& FBXNode);Returns true if the specified node is a bone.
static bool LoadFBXAsRuntimeLODByNode(UglTFRuntimeAsset* Asset, const FglTFRuntimeFBXNode& FBXNode, FglTFRuntimeMeshLOD& RuntimeLOD, bool& bIsSkeletal, const FglTFRuntimeMaterialsConfig& StaticMeshMaterialsConfig, const FglTFRuntimeMaterialsConfig& SkeletalMeshMaterialsConfig);Generates a glTFRuntime MeshLOD from an FBXNode. It is the basic structure for generating Static and SkeletalMeshes:
static UAnimSequence* LoadFBXAnimAsSkeletalMeshAnimation(UglTFRuntimeAsset* Asset, const FglTFRuntimeFBXAnim& FBXAnim, const FglTFRuntimeFBXNode& FBXNode, USkeletalMesh* SkeletalMesh, const FglTFRuntimeSkeletalAnimationConfig& SkeletalAnimationConfig);Generates an Animation Asset (supporting both bones and morph targets) starting from an FBXAnim. The Animation curves are generated for the specified FBXNode mesh and the related SkeletalMesh.
This function assumes you are extracting both the mesh and the animation from the same asset. If you need to extract an animation from a different FXB files (like the mixamo 'unskinned' ones) you can use the LoadFBXExternalAnimAsSkeletalMeshAnimation variant.
static UAnimSequence* LoadFBXExternalAnimAsSkeletalMeshAnimation(UglTFRuntimeAsset* Asset, const FglTFRuntimeFBXAnim& FBXAnim, USkeletalMesh* SkeletalMesh, const FglTFRuntimeSkeletalAnimationConfig& SkeletalAnimationConfig);Generates an Animation Asset (bones only) from an 'unskinned' FBX (animation curves without related meshes):
The system assumes that every animation curve has the same name of a bone in the provided SkeletalMesh asset.
Unfortunately the vast majority of FBX assets around use the Phong shading model, so a pretty raw conversion needs to be done.
Most of the work is done by the ufbx library, but it is not enough for a robust material management.
In addition to this the textures handling is extremely messy (you all experienced the missing textures in an imported FBX :( ).
The best approach is to embed the textures in the FBX itself, or to put the fbx and the textures in a zip file (that you can directly load).
If you want to hack/improve the material handling just look at the glTFRuntimeFBX::LoadMaterial function in glTFRuntimeFBXFunctionLibrary.cpp
The 'fbx' channel on the glTFRuntime discord server (https://discord.gg/DzS7MHy)
HEAT (https://heat.tech/) for providing the test assets and supporting the development.