Crash when compiling Mutable Customizable Object

Development Pipeline & Plugins
, ,
1

When using OpenCode to analyze the crash, this is what I’m getting back;

Root Cause

There is a bug in the header-copy phase of MergeMorphs at OpMeshMerge.h:130:

// Line 128 — copies MeshB.Morph.BatchesPerMorph[MeshBMorphIndex] batches
FMemory::Memcpy(..., MeshB.Morph.BatchesPerMorph[MeshBMorphIndex] * NumBatchHeaderDwords * sizeof(uint32));

// Line 130 — BUT advances the offset using Result's count (already incremented on line 115!)
BatchAccumulatedOffsetInDwords += MeshB.Morph.BatchesPerMorph[MorphIndex] * NumBatchHeaderDwords;
//                                                             ^^^^^^^^^^^ WRONG — should be MeshBMorphIndex

Line 115 first adds MeshB’s batch count into Result.Morph.BatchesPerMorph[MorphIndex]:

Result.Morph.BatchesPerMorph[MorphIndex] += MeshB.Morph.BatchesPerMorph[MeshBMorphIndex];

I made local changes to the OpMeshMerge.h in the Engine, but the crash persisted.

2

Hello Avian,

Some crashes with morph merging have been addressed for 5.8. For example, the issue you found with OpenCode has already been resolved. To have a better understanding of the problem we would need a callstack or, if possible, a simple reproduction case.

Thanks for reporting,

Genis.