fix(assimp): pass -f<format> so non-extension targets work#557
Merged
C4illin merged 3 commits intoC4illin:mainfrom Apr 22, 2026
Merged
fix(assimp): pass -f<format> so non-extension targets work#557C4illin merged 3 commits intoC4illin:mainfrom
C4illin merged 3 commits intoC4illin:mainfrom
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The assimp converter invokes `assimp export <in> <out>` and relies on
assimp's extension-based format inference to pick the output format.
That works for targets whose id happens to match a real file extension
(glb, gltf, obj, stl, ply, etc.) but silently fails for every target
whose assimp id is not a conventional filename extension:
glb2, gltf2, objnomtl, stlb, plyb, fbxa, assbin, assxml, pbrt, assjson
Picking any of those in the UI aborts the job with:
assimp export: no output format specified and I failed to guess it
assimp_cmd's `-f<h>` flag overrides extension inference, and the values
in `properties.to.object` already correspond 1:1 to assimp's format ids
(verified against `assimp listexport`). Passing `-f${convertTo}` makes
every advertised target work without changing anything else.
Reproduction: upload any .stl, convert to glb2. Before: ENOENT on the
nonexistent output file. After: valid binary glTF 2.0.
Follow-up to the previous commit. With `-f<format>` now passed to assimp, every advertised target exports successfully — but seven of them still produce files with assimp's internal format id as the extension, which no third-party viewer recognises: glb2 → .glb2 (really binary glTF 2.0, should be .glb) gltf2 → .gltf2 (text glTF 2.0, should be .gltf) objnomtl → .objnomtl (OBJ without .mtl, should be .obj) stlb → .stlb (binary STL, should be .stl) plyb → .plyb (binary PLY, should be .ply) fbxa → .fbxa (ASCII FBX, should be .fbx) assjson → .assjson (JSON dump, should be .json) Map these in `normalizeOutputFiletype`, the same helper that already handles jpeg→jpg, latex→tex, markdown→md. The format id on `convertTo` is untouched, so `assimp -f<id>` still selects the correct encoding/variant — only the output filename changes. assbin, assxml, and pbrt are both the format id and the canonical extension, so they need no mapping.
![cubic-dev-ai[bot]](https://avatars.githubusercontent.com/in/1082092?s=60&v=4){kind=small}
dantebarbieri
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Apr 22, 2026
Smoke test on the fork's fix/assimp-explicit-output-format branch passed (STL → glb2 produces a valid `.glb` binary glTF 2.0 file). Upstream PR filed at C4illin/ConvertX#557 — once merged, the next `:latest` pull picks up the fix. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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My ConvertX on my HomeServer failed to convert an STL file I found into a GLB file using the GLB2 format in
assimp.tools/assimp_cmd/Export.cpp:54 seems to indicate we need to pass
-f<h>where<h>is the format. And it can't infer since the extension for formatglb2is.glb: code/Common/Exporter.cpp:188. That's in line with the spec: https://github.com/KhronosGroup/glTF/blob/main/specification/2.0/Specification.adocBut if you just use
glb2with-fglb2, then the output from ConvertX is a.glb2file which must be renamed, so I altered thenormalizeOutputFiletypefunction to handle these filetypes in assimp.Shows this working in my self-hosted ConvertX instance.
Summary by cubic
Pass
-f<format>toassimp exportso non-extension format IDs (e.g.,glb2,stlb) export reliably, and write real file extensions so outputs open in viewers.Bug Fixes
assimp exportwith-f${convertTo}to bypass extension inference and fix failures for non-extension targets (glb2,gltf2,objnomtl,stlb,plyb,fbxa,assjson).glb2→.glb,gltf2→.gltf,objnomtl→.obj,stlb→.stl,plyb→.ply,fbxa→.fbx,assjson→.json.Refactors
assimp.ts(no behavior changes).Written for commit f7bbe71. Summary will update on new commits.