glTF2 : Fix ( An error occurs when it is 0 )#6544
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kimkulling merged 2 commits intoassimp:masterfrom Mar 16, 2026
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📝 WalkthroughWalkthroughThe glTF2 importer now skips allocation and population of triangle faces when Changes
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🧹 Nitpick comments (1)
code/AssetLib/glTF2/glTF2Importer.cpp (1)
769-775: Clean up the comment and consider consistency with other primitive modes.The fix correctly prevents an unnecessary allocation and a subsequent
DeadlyImportErrorwhen the index buffer results in zero faces. However, there are two concerns:
The comment
// copycd:: than > 0appears to be a personal note and is unclear. Please replace it with a descriptive comment explaining the intent.This guard is only applied to the indexed TRIANGLES case. The same issue exists for:
- Other indexed primitive modes (POINTS at line 729, LINES at line 742, LINE_LOOP/LINE_STRIP at line 752, TRIANGLE_STRIP at line 780, TRIANGLE_FAN at line 795)
- The non-indexed TRIANGLES case at line 850
- Other non-indexed primitive modes
Consider applying consistent guards to these cases as well.
Suggested comment fix
- // copycd:: than > 0 + // Skip allocation when there are no faces to avoid unnecessary allocation + // and subsequent "Mesh has no faces" error for empty primitives if (nFaces > 0) {🤖 Prompt for AI Agents
Verify each finding against the current code and only fix it if needed. In `@code/AssetLib/glTF2/glTF2Importer.cpp` around lines 769 - 775, Replace the unclear comment "// copycd:: than > 0" with a clear descriptive note (e.g., "Only allocate face array when computed face count > 0 to avoid allocating zero-sized array and subsequent DeadlyImportError") and add the same guard pattern used here around allocations that use nFaces (i.e., only allocate faces/new aiFace[nFaces] and iterate when nFaces > 0) for all other indexed primitive branches (POINTS, LINES, LINE_LOOP, LINE_STRIP, TRIANGLE_STRIP, TRIANGLE_FAN that use indexBuffer and SetFaceAndAdvance*/SetFaceAndAdvance2/SetFaceAndAdvance1 calls) and for non-indexed branches (including the non-indexed TRIANGLES case) so that facePtr/faces are only created when nFaces > 0 to maintain consistency and prevent zero-length allocations.
🤖 Prompt for all review comments with AI agents
Verify each finding against the current code and only fix it if needed.
Nitpick comments:
In `@code/AssetLib/glTF2/glTF2Importer.cpp`:
- Around line 769-775: Replace the unclear comment "// copycd:: than > 0" with a
clear descriptive note (e.g., "Only allocate face array when computed face count
> 0 to avoid allocating zero-sized array and subsequent DeadlyImportError") and
add the same guard pattern used here around allocations that use nFaces (i.e.,
only allocate faces/new aiFace[nFaces] and iterate when nFaces > 0) for all
other indexed primitive branches (POINTS, LINES, LINE_LOOP, LINE_STRIP,
TRIANGLE_STRIP, TRIANGLE_FAN that use indexBuffer and
SetFaceAndAdvance*/SetFaceAndAdvance2/SetFaceAndAdvance1 calls) and for
non-indexed branches (including the non-indexed TRIANGLES case) so that
facePtr/faces are only created when nFaces > 0 to maintain consistency and
prevent zero-length allocations.
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Actionable comments posted: 1
🤖 Prompt for all review comments with AI agents
Verify each finding against the current code and only fix it if needed.
Inline comments:
In `@code/AssetLib/glTF2/glTF2Importer.cpp`:
- Around line 769-775: The current indexed TRIANGLES path skips allocating
aiFace array when nFaces == 0 which leaves aim->mNumFaces at 0 and bypasses the
intended no-face validation; restore the previous validity contract by ensuring
faces/facePtr are allocated (or at least aim->mNumFaces is set and the no-face
error path is preserved) even when nFaces == 0. In practice, keep the allocation
guard semantics used previously: allocate faces = new aiFace[nFaces] and set
facePtr, and ensure SetFaceAndAdvance3 is only called within the loop over
count, but if nFaces == 0 explicitly preserve the error/validation behavior for
aim->mNumFaces (matching non-indexed TRIANGLES) so ValidateDataStructure.cpp can
catch the no-face condition. Reference symbols: nFaces, faces, facePtr, aiFace,
count, SetFaceAndAdvance3, and aim->mNumFaces.
ℹ️ Review info
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Configuration used: defaults
Review profile: CHILL
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Run ID: ab3580c7-09e1-48c2-9ab0-256281344c6b
📒 Files selected for processing (1)
code/AssetLib/glTF2/glTF2Importer.cpp
Comment on lines
+769
to
775
| // copycd:: than > 0 | ||
| if (nFaces > 0) { | ||
| facePtr = faces = new aiFace[nFaces]; | ||
| for (unsigned int i = 0; i < count; i += 3) { | ||
| SetFaceAndAdvance3(facePtr, aim->mNumVertices, indexBuffer[i], indexBuffer[i + 1], indexBuffer[i + 2]); | ||
| } | ||
| } |
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Preserve no-face validation instead of silently emitting an empty triangle mesh.
At Line 770, skipping allocation when nFaces == 0 bypasses the existing no-face error path, so indexed TRIANGLES can now leave aim->mNumFaces at 0. That conflicts with validation (code/PostProcessing/ValidateDataStructure.cpp, Line 342-Line 344) and with the non-indexed TRIANGLES path behavior.
Proposed fix (keep the allocation guard, keep previous validity contract)
case PrimitiveMode_TRIANGLES: {
nFaces = count / 3;
if (nFaces * 3 != count) {
ASSIMP_LOG_WARN("The number of vertices was not compatible with the TRIANGLES mode. Some vertices were dropped.");
count = nFaces * 3;
}
- // copycd:: than > 0
- if (nFaces > 0) {
- facePtr = faces = new aiFace[nFaces];
- for (unsigned int i = 0; i < count; i += 3) {
- SetFaceAndAdvance3(facePtr, aim->mNumVertices, indexBuffer[i], indexBuffer[i + 1], indexBuffer[i + 2]);
- }
- }
+ if (nFaces == 0) {
+ throw DeadlyImportError("Mesh \"", aim->mName.C_Str(), "\" has no faces");
+ }
+ facePtr = faces = new aiFace[nFaces];
+ for (unsigned int i = 0; i < count; i += 3) {
+ SetFaceAndAdvance3(facePtr, aim->mNumVertices, indexBuffer[i], indexBuffer[i + 1], indexBuffer[i + 2]);
+ }
break;
}🤖 Prompt for AI Agents
Verify each finding against the current code and only fix it if needed.
In `@code/AssetLib/glTF2/glTF2Importer.cpp` around lines 769 - 775, The current
indexed TRIANGLES path skips allocating aiFace array when nFaces == 0 which
leaves aim->mNumFaces at 0 and bypasses the intended no-face validation; restore
the previous validity contract by ensuring faces/facePtr are allocated (or at
least aim->mNumFaces is set and the no-face error path is preserved) even when
nFaces == 0. In practice, keep the allocation guard semantics used previously:
allocate faces = new aiFace[nFaces] and set facePtr, and ensure
SetFaceAndAdvance3 is only called within the loop over count, but if nFaces == 0
explicitly preserve the error/validation behavior for aim->mNumFaces (matching
non-indexed TRIANGLES) so ValidateDataStructure.cpp can catch the no-face
condition. Reference symbols: nFaces, faces, facePtr, aiFace, count,
SetFaceAndAdvance3, and aim->mNumFaces.
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Merged, thank you for your contribution. |
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29187.zip
I attached a file that used at test.
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