[Bf-blender-cvs] [0012d54a70a] master: Alembic import: fixed mesh corruption when changing topology

[Sybren A. Stüvel]

Commit: 0012d54a70ac1dcd83531a32d1fe3ab017034e4b
Author: Sybren A. Stüvel
Date:   Sun Oct 29 13:55:42 2017 +0100
Branches: master
https://developer.blender.org/rB0012d54a70ac1dcd83531a32d1fe3ab017034e4b

Alembic import: fixed mesh corruption when changing topology

When the mesh changed topology but kept the vertex count the same, it would
result in a corrupt mesh. By checking the face & loop counts too, this has
become less likely.

I've checked IPolyMeshSchema::isConstant(), but it returns true even when
we see that the mesh changed topology.

===================================================================

M	source/blender/alembic/intern/abc_mesh.cc

===================================================================

diff --git a/source/blender/alembic/intern/abc_mesh.cc b/source/blender/alembic/intern/abc_mesh.cc
index 6545ced8e4a..36b134f8b0c 100644
--- a/source/blender/alembic/intern/abc_mesh.cc
+++ b/source/blender/alembic/intern/abc_mesh.cc
@@ -1082,7 +1082,10 @@ DerivedMesh *AbcMeshReader::read_derivedmesh(DerivedMesh *dm,
 	ImportSettings settings;
 	settings.read_flag |= read_flag;
 
-	if (dm->getNumVerts(dm) != positions->size()) {
+	bool topology_changed =  positions->size() != dm->getNumVerts(dm) ||
+	                         face_counts->size() != dm->getNumPolys(dm) ||
+	                         face_indices->size() != dm->getNumLoops(dm);
+	if (topology_changed) {
 		new_dm = CDDM_from_template(dm,
 		                            positions->size(),
 		                            0,