Fix segfaults when deleting objects with upstream bullet lib

Blender tried to free objects twice from the bullet world sometime.

First we would implicity remove all objects when recreating the bullet
world and then explicity try to remove them again from the now empty
world.

This would wouldn't crash older bullet versions, but the recent versions
will as we will try to free objects that no longer exists in the bullet
world.

Also clear the cache on deletion as the object order changes.
Fix T77181: The cache clearing will fix this issue.

1 files changed, 11 insertions, 3 deletions

diff --git a/source/blender/blenkernel/intern/rigidbody.c b/source/blender/blenkernel/intern/rigidbody.c
index 00b993296d0..7eab716d805 100644
--- a/source/blender/blenkernel/intern/rigidbody.c
+++ b/source/blender/blenkernel/intern/rigidbody.c
@@ -174,7 +174,7 @@ void BKE_rigidbody_free_object(Object *ob, RigidBodyWorld *rbw)
   /* free physics references */
   if (is_orig) {
     if (rbo->shared->physics_object) {
-      if (rbw != NULL) {
+      if (rbw != NULL && rbw->shared->physics_world != NULL) {
         /* We can only remove the body from the world if the world is known.
          * The world is generally only unknown if it's an evaluated copy of
          * an object that's being freed, in which case this code isn't run anyway. */
@@ -185,7 +185,7 @@ void BKE_rigidbody_free_object(Object *ob, RigidBodyWorld *rbw)
          * loop over all scenes then. */
         for (Scene *scene = G_MAIN->scenes.first; scene != NULL; scene = scene->id.next) {
           RigidBodyWorld *scene_rbw = scene->rigidbody_world;
-          if (scene_rbw != NULL) {
+          if (scene_rbw != NULL && scene_rbw->shared->physics_world != NULL) {
             RB_dworld_remove_body(scene_rbw->shared->physics_world, rbo->shared->physics_object);
           }
         }
@@ -816,7 +816,9 @@ static void rigidbody_validate_sim_object(RigidBodyWorld *rbw, Object *ob, bool
     rigidbody_validate_sim_shape(rbw, ob, true);
   }
 
-  if (rbo->shared->physics_object) {
+  if (rbo->shared->physics_object && !rebuild) {
+    /* Don't remove body on rebuild as it has already been removed when deleting and rebuilding the
+     * world. */
     RB_dworld_remove_body(rbw->shared->physics_world, rbo->shared->physics_object);
   }
   if (!rbo->shared->physics_object || rebuild) {
@@ -1559,6 +1561,10 @@ void BKE_rigidbody_remove_object(Main *bmain, Scene *scene, Object *ob, const bo
 
   /* flag cache as outdated */
   BKE_rigidbody_cache_reset(rbw);
+  /* Reset cache as the object order probably changed after freeing the object. */
+  PTCacheID pid;
+  BKE_ptcache_id_from_rigidbody(&pid, NULL, rbw);
+  BKE_ptcache_id_reset(scene, &pid, PTCACHE_RESET_OUTDATED);
 
   /* Dependency graph update */
   DEG_relations_tag_update(bmain);
@@ -1771,6 +1777,8 @@ static void rigidbody_update_simulation(Depsgraph *depsgraph,
    * T70667). */
   if (rebuild || rbw->shared->physics_world == NULL) {
     BKE_rigidbody_validate_sim_world(scene, rbw, rebuild);
+    /* We have rebuilt the world so we need to make sure the rest is rebuilt as well. */
+    rebuild = true;
   }
 
   rigidbody_update_sim_world(scene, rbw);