From bebdb6c8249939623f80cc72433aa7d7418444bf Mon Sep 17 00:00:00 2001
From: Bastien Montagne <montagne29@wanadoo.fr>
Date: Fri, 4 Oct 2019 18:51:00 +0200
Subject: Fix assert when deleting a RBW constraint object.

Side-reported in T70505.

Code did not ensure deleted object was removed from the RBW constraints
collection, leading to some invalid status (object in constraints
collection but without relevant contraints data).

Also fixed another issue - code deleting RBW objects would try to remove
any constraint one using it as target, in a very bad and broken way,
since you cannot iterate over objects of a collection while removing
some... Now instead just NULLify relevant pointers... I hope it works,
otherwise we'll have to take a different approach.

Needless to stress again how weak the whole RBW code is in general, and
regarding same object being used by RBW in more than one scene in particular,
that is known broken situation anyway.
---
 source/blender/blenkernel/intern/rigidbody.c | 34 ++++++++++++++++++++--------
 1 file changed, 24 insertions(+), 10 deletions(-)

(limited to 'source/blender/blenkernel/intern/rigidbody.c')

diff --git a/source/blender/blenkernel/intern/rigidbody.c b/source/blender/blenkernel/intern/rigidbody.c
index 514f000d73d..c7a5104619b 100644
--- a/source/blender/blenkernel/intern/rigidbody.c
+++ b/source/blender/blenkernel/intern/rigidbody.c
@@ -1415,7 +1415,7 @@ bool BKE_rigidbody_add_object(Main *bmain, Scene *scene, Object *ob, int type, R
   return true;
 }
 
-void BKE_rigidbody_remove_object(Main *bmain, Scene *scene, Object *ob)
+void BKE_rigidbody_remove_object(Main *bmain, Scene *scene, Object *ob, const bool free_us)
 {
   RigidBodyWorld *rbw = scene->rigidbody_world;
   RigidBodyCon *rbc;
@@ -1438,8 +1438,13 @@ void BKE_rigidbody_remove_object(Main *bmain, Scene *scene, Object *ob)
       FOREACH_COLLECTION_OBJECT_RECURSIVE_BEGIN (rbw->constraints, obt) {
         if (obt && obt->rigidbody_constraint) {
           rbc = obt->rigidbody_constraint;
-          if (ELEM(ob, rbc->ob1, rbc->ob2)) {
-            BKE_rigidbody_remove_constraint(scene, obt);
+          if (rbc->ob1 == ob) {
+            rbc->ob1 = NULL;
+            DEG_id_tag_update(&obt->id, ID_RECALC_COPY_ON_WRITE);
+          }
+          if (rbc->ob2 == ob) {
+            rbc->ob2 = NULL;
+            DEG_id_tag_update(&obt->id, ID_RECALC_COPY_ON_WRITE);
           }
         }
       }
@@ -1454,7 +1459,7 @@ void BKE_rigidbody_remove_object(Main *bmain, Scene *scene, Object *ob)
        * when we remove them from RB simulation. */
       BKE_collection_object_add(bmain, scene->master_collection, ob);
     }
-    BKE_collection_object_remove(bmain, rbw->group, ob, false);
+    BKE_collection_object_remove(bmain, rbw->group, ob, free_us);
   }
 
   /* remove object's settings */
@@ -1468,15 +1473,24 @@ void BKE_rigidbody_remove_object(Main *bmain, Scene *scene, Object *ob)
   DEG_id_tag_update(&ob->id, ID_RECALC_TRANSFORM);
 }
 
-void BKE_rigidbody_remove_constraint(Scene *scene, Object *ob)
+void BKE_rigidbody_remove_constraint(Main *bmain, Scene *scene, Object *ob, const bool free_us)
 {
   RigidBodyWorld *rbw = scene->rigidbody_world;
   RigidBodyCon *rbc = ob->rigidbody_constraint;
 
-  /* remove from rigidbody world, free object won't do this */
-  if (rbw && rbw->shared->physics_world && rbc->physics_constraint) {
-    RB_dworld_remove_constraint(rbw->shared->physics_world, rbc->physics_constraint);
+  if (rbw != NULL) {
+    /* Remove from RBW constraints collection. */
+    if (rbw->constraints != NULL) {
+      BKE_collection_object_remove(bmain, rbw->constraints, ob, free_us);
+      DEG_id_tag_update(&rbw->constraints->id, ID_RECALC_COPY_ON_WRITE);
+    }
+
+    /* remove from rigidbody world, free object won't do this */
+    if (rbw->shared->physics_world && rbc->physics_constraint) {
+      RB_dworld_remove_constraint(rbw->shared->physics_world, rbc->physics_constraint);
+    }
   }
+
   /* remove object's settings */
   BKE_rigidbody_free_constraint(ob);
 
@@ -2086,10 +2100,10 @@ bool BKE_rigidbody_add_object(Main *bmain, Scene *scene, Object *ob, int type, R
   return false;
 }
 
-void BKE_rigidbody_remove_object(struct Main *bmain, Scene *scene, Object *ob)
+void BKE_rigidbody_remove_object(struct Main *bmain, Scene *scene, Object *ob, const bool free_us)
 {
 }
-void BKE_rigidbody_remove_constraint(Scene *scene, Object *ob)
+void BKE_rigidbody_remove_constraint(Main *bmain, Scene *scene, Object *ob, const bool free_us)
 {
 }
 void BKE_rigidbody_sync_transforms(RigidBodyWorld *rbw, Object *ob, float ctime)
-- 
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