FBXLoader: Loading FBX files with out-of-bounds material assignments lead to incorrect geometry groups and subsequent errors #30581
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…lead to incorrect geometry groups and subsequent errors In line with other FBX loaders, a default material is now created.
Mugen87
reviewed
Feb 21, 2025
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| if ( needsDefaultMaterial ) { | ||
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| const defaultMaterial = new MeshStandardMaterial(); |
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Can we use MeshPhongMaterial here? FBXLoader already uses MeshPhongMaterial as a default material in parseMaterial().
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Description
The previous behaviour was a visual hole (invalid material) and hard-to-catch errors e.g. when using
Mesh._computeIntersectionsorSkinnedMesh._computeIntersections.In line with other FBX loaders (tested in Unity/Blender/F3D), a default material is now created. Note that "default material" is to be taken literal; the material looks different in all implementations I tested because their defaults differ, so I decided that's the most reasonable approach here as well.
Reproduction file:
response.fbx.zip
Screenshots
The hot pink parts have an invalid materialIndex already in the underlying FBX data (there's 6 materials in the file, the index here is "8"):
Unity just uses an existing default material for that problematic slot:
Blender just kicks out the wrong group and thus uses whatever the "last valid" material was, which is super confusing (e.g. if the last valid material was textured, that texture is now on random geometry).
This contribution is funded by Needle