Fix T46677: OpenSubdiv crashes when witching from simple and CC subdivisions

Crash was happening due to OpenGL free from the non-main thread. Ideally we need
to implement somewhat delayed unused buffer free for OpenSubdiv similar to what we
are doing in GPU module.

1 files changed, 16 insertions, 7 deletions

diff --git a/source/blender/blenkernel/intern/scene.c b/source/blender/blenkernel/intern/scene.c
index bb61ecd63cb..b3fa6018517 100644
--- a/source/blender/blenkernel/intern/scene.c
+++ b/source/blender/blenkernel/intern/scene.c
@@ -1598,7 +1598,8 @@ static void scene_free_unused_opensubdiv_cache(Scene *scene)
 			ModifierData *md = object->modifiers.last;
 			if (md != NULL && md->type == eModifierType_Subsurf) {
 				SubsurfModifierData *smd = (SubsurfModifierData *) md;
-				bool object_in_editmode = object->mode == OB_MODE_EDIT;
+				const bool object_in_editmode = (object->mode == OB_MODE_EDIT);
+				const bool use_simple = (smd->subdivType == ME_SIMPLE_SUBSURF);
 				if (!smd->use_opensubdiv ||
 				    DAG_get_eval_flags_for_object(scene, object) & DAG_EVAL_NEED_CPU)
 				{
@@ -1609,13 +1610,21 @@ static void scene_free_unused_opensubdiv_cache(Scene *scene)
 						ccgSubSurf_free_osd_mesh(smd->emCache);
 					}
 				}
-				if (object_in_editmode && smd->mCache != NULL) {
-					ccgSubSurf_free(smd->mCache);
-					smd->mCache = NULL;
+				if (smd->mCache != NULL) {
+					if (object_in_editmode ||
+					    ccgSubSurf_getSimpleSubdiv(smd->mCache) != use_simple)
+					{
+						ccgSubSurf_free(smd->mCache);
+						smd->mCache = NULL;
+					}
 				}
-				if (!object_in_editmode && smd->emCache != NULL) {
-					ccgSubSurf_free(smd->emCache);
-					smd->emCache = NULL;
+				if (smd->emCache != NULL) {
+					if (!object_in_editmode ||
+					    ccgSubSurf_getSimpleSubdiv(smd->emCache) != use_simple)
+					{
+						ccgSubSurf_free(smd->emCache);
+						smd->emCache = NULL;
+					}
 				}
 			}
 		}