Fix T88026: Repeated switch to rendered viewport crashes

Resolve ownership ambiguity with shared physics pointers.

Previously, LIB_ID_CREATE_NO_MAIN allowed pointer sharing with
the source ID so physics caches can be shared between original and
evaluated data: (Object.soft.shared & Object.rigidbody_object.shared).

This only worked properly for LIB_TAG_COPIED_ON_WRITE ID's,
as LIB_TAG_NO_MAIN can be used in situations where the original ID's
lifetime limited by it's original data.

This commit adds `LIB_ID_COPY_SET_COPIED_ON_WRITE` so ID's only share
memory with original data for ID's evaluated in the depsgraph.

For all other uses, a full copy of physics data is made.

Ref D11228#287094

1 files changed, 3 insertions, 1 deletions

diff --git a/source/blender/blenkernel/intern/rigidbody.c b/source/blender/blenkernel/intern/rigidbody.c
index 19078446009..2539b990210 100644
--- a/source/blender/blenkernel/intern/rigidbody.c
+++ b/source/blender/blenkernel/intern/rigidbody.c
@@ -260,10 +260,12 @@ static RigidBodyOb *rigidbody_copy_object(const Object *ob, const int flag)
   RigidBodyOb *rboN = NULL;
 
   if (ob->rigidbody_object) {
+    const bool is_orig = (flag & LIB_ID_COPY_SET_COPIED_ON_WRITE) == 0;
+
     /* just duplicate the whole struct first (to catch all the settings) */
     rboN = MEM_dupallocN(ob->rigidbody_object);
 
-    if ((flag & LIB_ID_CREATE_NO_MAIN) == 0) {
+    if (is_orig) {
       /* This is a regular copy, and not a CoW copy for depsgraph evaluation */
       rboN->shared = MEM_callocN(sizeof(*rboN->shared), "RigidBodyOb_Shared");
     }