Add support for glTF line primitives #1736
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Description
This PR adds support for the
LINES,LINE_LOOP, andLINE_STRIPprimitive modes in glTF.Apparently the only line mode supported in Unreal is
PT_LineList, so the other two have to be converted into line lists with duplicate indices.Author checklist
CHANGES.mdwith a short summary of my change (for user-facing changes).[ ] I have added or updated unit tests to ensure consistent code coverage as necessary.[ ] I have updated the documentation as necessary.Remaining Tasks
The normals are off somehow for this model and I haven't figured out why? I added a clause to disable flat normal generation for non-triangle models (since that doesn't make much sense), but there's still some lighting variation among the lines themselves. You can see it when the sun angle is really extreme. 🤔
Testing plan
Load this tileset under a georeference with True Origin: MeshPrimitiveModes.zip
Reference screenshot for this sample model here: https://github.com/KhronosGroup/glTF-Sample-Assets/tree/main/Models/MeshPrimitiveModes