Texturing: make the keep-existing-UVs path reachable (and non-crashing once it is) - #173
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xocialize wants to merge 1 commit into
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Texturing: make the keep-existing-UVs path reachable (and non-crashing once it is)#173xocialize wants to merge 1 commit into
xocialize wants to merge 1 commit into
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- preprocess_mesh: carry mesh.visual through the rebuilt Trimesh. run() normalizes the mesh before postprocess_mesh ever sees it, so dropping the visual made the keep-existing-UVs branch unreachable via the public API. Vertex order is unchanged, so per-vertex UVs stay valid. - postprocess_mesh: copy vertices/faces/normals up front. trimesh's vertex_normals cache is read-only and the glTF axis swap writes in place; only the uv-unwrap branch happened to replace these with fresh arrays. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
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Problem
Trellis2TexturingPipeline.postprocess_meshimplements a keep-existing-UVs branch, but it is unreachable viarun():preprocess_meshrebuilds the mesh astrimesh.Trimesh(vertices=vertices, faces=mesh.faces, process=False)and dropsmesh.visual, so by the timepostprocess_meshchecksmesh.visual.uv, the UVs are always gone and every input falls into the uv-unwrap branch. The shipped "texture an existing mesh preserving its UVs" capability silently never engages.Fix
preprocess_mesh: passvisual=mesh.visualthrough the rebuiltTrimesh. The rebuild doesn't change vertex order (only positions), so per-vertex UVs remain valid.postprocess_mesh: copyvertices/faces/normalswithnp.array()up front.mesh.vertex_normalsis a read-only trimesh cache, and the glTF axis swap at the end writes it in place (normals[:, 1], normals[:, 2] = ...). Today only the uv-unwrap branch runs, and it happens to replacenormalswith a fresh indexed array — so this second bug is latent until fix (1) makes the UV-preserve branch reachable, at which point it crashes. The two fixes belong in the same PR.Evidence
With these changes, re-texturing an existing UV-mapped mesh preserves its UVs bit-identically — we measured max UV delta 0.0 between input and output in production use (Apple Silicon port work, https://github.com/xocialize/trellis2-apple).
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