OpenSubdiv: Completely avoid possible access to non-existing CPU data

Make it so CCGDM reports 0 number of geometry when it uses GPU backend for
drawing. This screws up a bit statistics in info header and requires to have
some special handle of CCGDM in the drawing code, but makes it so non of the
areas will try to access non-existing geometry.

1 files changed, 22 insertions, 0 deletions

diff --git a/source/blender/blenkernel/intern/subsurf_ccg.c b/source/blender/blenkernel/intern/subsurf_ccg.c
index 617bf70c081..9971a9ef141 100644
--- a/source/blender/blenkernel/intern/subsurf_ccg.c
+++ b/source/blender/blenkernel/intern/subsurf_ccg.c
@@ -4850,3 +4850,25 @@ void subsurf_calculate_limit_positions(Mesh *me, float (*r_positions)[3])
 
 	dm->release(dm);
 }
+
+bool subsurf_has_edges(DerivedMesh *dm)
+{
+	CCGDerivedMesh *ccgdm = (CCGDerivedMesh *) dm;
+#ifdef WITH_OPENSUBDIV
+	if (ccgdm->useGpuBackend) {
+		return true;
+	}
+#endif
+	return dm->getNumEdges(dm) != 0;
+}
+
+bool subsurf_has_faces(DerivedMesh *dm)
+{
+	CCGDerivedMesh *ccgdm = (CCGDerivedMesh *) dm;
+#ifdef WITH_OPENSUBDIV
+	if (ccgdm->useGpuBackend) {
+		return true;
+	}
+#endif
+	return dm->getNumPolys(dm) != 0;
+}