OpenSubdiv: Avoid crashes when GPU subsurf is tried to be used on CPU

The issue was caused by CCG code being confused by number of geometry returned
by utility functions in the case of the skipped grids.

Made it so that code is always only working with CCG data and handled drawing
code in a bit special way now.

This solves such crashes as i.e. snapping.

4 files changed, 10 insertions, 73 deletions

diff --git a/source/blender/blenkernel/intern/CCGSubSurf.c b/source/blender/blenkernel/intern/CCGSubSurf.c
index b78c3c77aa4..d952e68696e 100644
--- a/source/blender/blenkernel/intern/CCGSubSurf.c
+++ b/source/blender/blenkernel/intern/CCGSubSurf.c
@@ -1191,39 +1191,15 @@ CCGError ccgSubSurf_stitchFaces(CCGSubSurf *ss, int lvl, CCGFace **effectedF, in
 
 int ccgSubSurf_getNumVerts(const CCGSubSurf *ss)
 {
-#ifdef WITH_OPENSUBDIV
-	if (ss->skip_grids) {
-		return ccgSubSurf__getNumOsdBaseVerts(ss);
-	}
-	else
-#endif
-	{
-		return ss->vMap->numEntries;
-	}
+	return ss->vMap->numEntries;
 }
 int ccgSubSurf_getNumEdges(const CCGSubSurf *ss)
 {
-#ifdef WITH_OPENSUBDIV
-	if (ss->skip_grids) {
-		return ccgSubSurf__getNumOsdBaseEdges(ss);
-	}
-	else
-#endif
-	{
-		return ss->eMap->numEntries;
-	}
+	return ss->eMap->numEntries;
 }
 int ccgSubSurf_getNumFaces(const CCGSubSurf *ss)
 {
-#ifdef WITH_OPENSUBDIV
-	if (ss->skip_grids) {
-		return ccgSubSurf__getNumOsdBaseFaces(ss);
-	}
-	else
-#endif
-	{
-		return ss->fMap->numEntries;
-	}
+	return ss->fMap->numEntries;
 }
 
 CCGVert *ccgSubSurf_getVert(CCGSubSurf *ss, CCGVertHDL v)
diff --git a/source/blender/blenkernel/intern/CCGSubSurf_intern.h b/source/blender/blenkernel/intern/CCGSubSurf_intern.h
index d80bdcdb7fc..95ea91461f8 100644
--- a/source/blender/blenkernel/intern/CCGSubSurf_intern.h
+++ b/source/blender/blenkernel/intern/CCGSubSurf_intern.h
@@ -303,10 +303,6 @@ void ccgSubSurf__sync_legacy(CCGSubSurf *ss);
 
 void ccgSubSurf__sync_opensubdiv(CCGSubSurf *ss);
 
-int ccgSubSurf__getNumOsdBaseVerts(const CCGSubSurf *ss);
-int ccgSubSurf__getNumOsdBaseEdges(const CCGSubSurf *ss);
-int ccgSubSurf__getNumOsdBaseFaces(const CCGSubSurf *ss);
-
 /* * CCGSubSurf_opensubdiv_converter.c * */
 
 struct OpenSubdiv_Converter;
diff --git a/source/blender/blenkernel/intern/CCGSubSurf_opensubdiv.c b/source/blender/blenkernel/intern/CCGSubSurf_opensubdiv.c
index c6c8f14dd2c..c7526521963 100644
--- a/source/blender/blenkernel/intern/CCGSubSurf_opensubdiv.c
+++ b/source/blender/blenkernel/intern/CCGSubSurf_opensubdiv.c
@@ -863,46 +863,4 @@ void ccgSubSurf__sync_opensubdiv(CCGSubSurf *ss)
 #endif
 }
 
-static const OpenSubdiv_TopologyRefinerDescr *get_effective_refiner(
-        const CCGSubSurf *ss)
-{
-	if (ss->osd_topology_refiner != NULL) {
-		return ss->osd_topology_refiner;
-	}
-	if (ss->osd_mesh != NULL) {
-		return openSubdiv_getGLMeshTopologyRefiner(ss->osd_mesh);
-	}
-	return 0;
-}
-
-int ccgSubSurf__getNumOsdBaseVerts(const CCGSubSurf *ss)
-{
-	const OpenSubdiv_TopologyRefinerDescr *topology_refiner =
-	        get_effective_refiner(ss);
-	if (topology_refiner == NULL) {
-		return 0;
-	}
-	return openSubdiv_topologyRefinerGetNumVerts(topology_refiner);
-}
-
-int ccgSubSurf__getNumOsdBaseEdges(const CCGSubSurf *ss)
-{
-	const OpenSubdiv_TopologyRefinerDescr *topology_refiner =
-	        get_effective_refiner(ss);
-	if (topology_refiner == NULL) {
-		return 0;
-	}
-	return openSubdiv_topologyRefinerGetNumEdges(topology_refiner);
-}
-
-int ccgSubSurf__getNumOsdBaseFaces(const CCGSubSurf *ss)
-{
-	const OpenSubdiv_TopologyRefinerDescr *topology_refiner =
-	        get_effective_refiner(ss);
-	if (topology_refiner == NULL) {
-		return 0;
-	}
-	return openSubdiv_topologyRefinerGetNumFaces(topology_refiner);
-}
-
 #endif  /* WITH_OPENSUBDIV */
diff --git a/source/blender/blenkernel/intern/subsurf_ccg.c b/source/blender/blenkernel/intern/subsurf_ccg.c
index 71e14eba690..cfc9c32e81e 100644
--- a/source/blender/blenkernel/intern/subsurf_ccg.c
+++ b/source/blender/blenkernel/intern/subsurf_ccg.c
@@ -4551,13 +4551,20 @@ static CCGDerivedMesh *getCCGDerivedMesh(CCGSubSurf *ss,
                                          DerivedMesh *dm,
                                          bool use_gpu_backend)
 {
+#ifdef WITH_OPENSUBDIV
+	const int totedge = dm->getNumEdges(dm);
+	const int totface = dm->getNumPolys(dm);
+#else
 	const int totedge = ccgSubSurf_getNumEdges(ss);
 	const int totface = ccgSubSurf_getNumFaces(ss);
+#endif
 	CCGDerivedMesh *ccgdm = MEM_callocN(sizeof(*ccgdm), "ccgdm");
 	int numTex, numCol;
 	int hasPCol, hasOrigSpace;
 
 	if (use_gpu_backend == false) {
+		BLI_assert(totedge == ccgSubSurf_getNumEdges(ss));
+		BLI_assert(totface == ccgSubSurf_getNumFaces(ss));
 		DM_from_template(&ccgdm->dm, dm, DM_TYPE_CCGDM,
 		                 ccgSubSurf_getNumFinalVerts(ss),
 		                 ccgSubSurf_getNumFinalEdges(ss),