Yet another fix for crashes when drawing empty base mesh with constructive modifier. This crashed with ocean modifier (#29241). The previous fix was to avoid drawing mapped faces altogether for empty edit mesh, but that also disables the actual derived mesh display (#29346).

The real reason for this crash is that ocean modifier (in generative setting) does not properly set the derived mesh face ORIGINDEX data to ORIGINDEX_NONE. With this the previous fixes are not necessary.

1 files changed, 5 insertions, 0 deletions

diff --git a/source/blender/modifiers/intern/MOD_ocean.c b/source/blender/modifiers/intern/MOD_ocean.c
index 3ba49f26449..db98c223416 100644
--- a/source/blender/modifiers/intern/MOD_ocean.c
+++ b/source/blender/modifiers/intern/MOD_ocean.c
@@ -277,6 +277,7 @@ static DerivedMesh *generate_ocean_geometry(OceanModifierData *omd)
 	MVert *mv;
 	MFace *mf;
 	MTFace *tf;
+	int *origindex;
 
 	int cdlayer;
 
@@ -305,6 +306,7 @@ static DerivedMesh *generate_ocean_geometry(OceanModifierData *omd)
 
 	mv = CDDM_get_verts(result);
 	mf = CDDM_get_faces(result);
+	origindex= result->getFaceDataArray(result, CD_ORIGINDEX);
 
 	/* create vertices */
 	#pragma omp parallel for private(x, y) if (rx > OMP_MIN_RES)
@@ -329,6 +331,9 @@ static DerivedMesh *generate_ocean_geometry(OceanModifierData *omd)
 			mf[fi].v4 = vi + res_x+1;
 
 			mf[fi].flag |= ME_SMOOTH;
+
+			/* generated geometry does not map to original faces */
+			origindex[fi] = ORIGINDEX_NONE;
 		}
 	}