Fix T72593 Blender crashes when modifier change the material count

Instead of changing the modifiers behavior, we make sure to always use
the data->totcol instead of the ob->totcol. Also we centralize getting
this number to avoid future issues.

Fix T72593 Blender crashes when separating mesh
Fix T72017 Crash on set visibility change

1 files changed, 8 insertions, 0 deletions

diff --git a/source/blender/draw/intern/draw_cache_impl_metaball.c b/source/blender/draw/intern/draw_cache_impl_metaball.c
index e3bfcbde3ef..c14e66c2b47 100644
--- a/source/blender/draw/intern/draw_cache_impl_metaball.c
+++ b/source/blender/draw/intern/draw_cache_impl_metaball.c
@@ -25,6 +25,7 @@
 
 #include "MEM_guardedalloc.h"
 
+#include "BLI_math_base.h"
 #include "BLI_utildefines.h"
 
 #include "DNA_meta_types.h"
@@ -206,6 +207,8 @@ GPUBatch **DRW_metaball_batch_cache_get_surface_shaded(Object *ob,
     return NULL;
   }
 
+  BLI_assert(gpumat_array_len == DRW_metaball_material_count_get(mb));
+
   MetaBallBatchCache *cache = metaball_batch_cache_get(mb);
   if (cache->shaded_triangles == NULL) {
     cache->mat_len = gpumat_array_len;
@@ -270,3 +273,8 @@ struct GPUBatch *DRW_metaball_batch_cache_get_edge_detection(struct Object *ob,
 
   return cache->edge_detection;
 }
+
+int DRW_metaball_material_count_get(MetaBall *mb)
+{
+  return max_ii(1, mb->totcol);
+}