EEVEE: Fix crash when using animated visibility with motion blur steps

This was caused by the same VBO being remapped twice by
`EEVEE_motion_blur_cache_finish`. Leading to memory corruption.

1 files changed, 9 insertions, 5 deletions

diff --git a/source/blender/draw/engines/eevee/eevee_motion_blur.c b/source/blender/draw/engines/eevee/eevee_motion_blur.c
index 530becfe771..59842ec50f7 100644
--- a/source/blender/draw/engines/eevee/eevee_motion_blur.c
+++ b/source/blender/draw/engines/eevee/eevee_motion_blur.c
@@ -457,9 +457,6 @@ void EEVEE_motion_blur_cache_finish(EEVEE_Data *vedata)
         }
         else {
           GPUVertBuf *vbo = mb_geom->vbo[mb_step];
-          /* If this assert fails, it means that different EEVEE_GeometryMotionDatas
-           * has been used for each motion blur step.  */
-          BLI_assert(vbo);
           if (vbo) {
             /* Use the vbo to perform the copy on the GPU. */
             GPU_vertbuf_use(vbo);
@@ -470,6 +467,10 @@ void EEVEE_motion_blur_cache_finish(EEVEE_Data *vedata)
             int attrib_id = GPU_vertformat_attr_id_get(format, "pos");
             GPU_vertformat_attr_rename(format, attrib_id, (mb_step == MB_PREV) ? "prv" : "nxt");
           }
+          else {
+            /* This might happen if the object visibility has been animated. */
+            mb_geom->use_deform = false;
+          }
         }
         break;
 
@@ -515,6 +516,8 @@ void EEVEE_motion_blur_swap_data(EEVEE_Data *vedata)
           DRW_TEXTURE_FREE_SAFE(mb_hair->psys[i].hair_pos_tx[MB_PREV]);
           mb_hair->psys[i].hair_pos[MB_PREV] = mb_hair->psys[i].hair_pos[MB_NEXT];
           mb_hair->psys[i].hair_pos_tx[MB_PREV] = mb_hair->psys[i].hair_pos_tx[MB_NEXT];
+          mb_hair->psys[i].hair_pos[MB_NEXT] = NULL;
+          mb_hair->psys[i].hair_pos_tx[MB_NEXT] = NULL;
         }
         break;
 
@@ -529,9 +532,10 @@ void EEVEE_motion_blur_swap_data(EEVEE_Data *vedata)
         }
         GPU_VERTBUF_DISCARD_SAFE(mb_geom->vbo[MB_PREV]);
         mb_geom->vbo[MB_PREV] = mb_geom->vbo[MB_NEXT];
+        mb_geom->vbo[MB_NEXT] = NULL;
 
-        if (mb_geom->vbo[MB_NEXT]) {
-          GPUVertBuf *vbo = mb_geom->vbo[MB_NEXT];
+        if (mb_geom->vbo[MB_PREV]) {
+          GPUVertBuf *vbo = mb_geom->vbo[MB_PREV];
           GPUVertFormat *format = (GPUVertFormat *)GPU_vertbuf_get_format(vbo);
           int attrib_id = GPU_vertformat_attr_id_get(format, "nxt");
           GPU_vertformat_attr_rename(format, attrib_id, "prv");