Fix Rigidbody depsgraph passive and constraint transform relations.

We need to have transforms from passive objects if they are animated or
driven by parent relations. This is not immediately obvious as the
object transform matrix will still be available, it is just one frame
behind in some cases.

Fixed dependency cycles if there is a constraint between two rigid
bodies. Because bullet keeps track of its simulated bodies, we do not
need to supply objects transforms as bullet should already have them.

I need combine these two fixes because otherwise we will get depsgraph
warnings that nodes are missing that it expects to be there.

Reviewed By: Sergey, Jacques

Differential Revision: http://developer.blender.org/D8732

2 files changed, 19 insertions, 6 deletions

diff --git a/source/blender/blenkernel/BKE_rigidbody.h b/source/blender/blenkernel/BKE_rigidbody.h
index c2059144388..ae1e437cd60 100644
--- a/source/blender/blenkernel/BKE_rigidbody.h
+++ b/source/blender/blenkernel/BKE_rigidbody.h
@@ -143,6 +143,7 @@ void BKE_rigidbody_aftertrans_update(struct Object *ob,
                                      float rotAngle);
 void BKE_rigidbody_sync_transforms(struct RigidBodyWorld *rbw, struct Object *ob, float ctime);
 bool BKE_rigidbody_check_sim_running(struct RigidBodyWorld *rbw, float ctime);
+bool BKE_rigidbody_is_affected_by_simulation(struct Object *ob);
 void BKE_rigidbody_cache_reset(struct RigidBodyWorld *rbw);
 void BKE_rigidbody_rebuild_world(struct Depsgraph *depsgraph, struct Scene *scene, float ctime);
 void BKE_rigidbody_do_simulation(struct Depsgraph *depsgraph, struct Scene *scene, float ctime);
diff --git a/source/blender/blenkernel/intern/rigidbody.c b/source/blender/blenkernel/intern/rigidbody.c
index ece7d0f9136..13c791ffa85 100644
--- a/source/blender/blenkernel/intern/rigidbody.c
+++ b/source/blender/blenkernel/intern/rigidbody.c
@@ -1901,21 +1901,33 @@ bool BKE_rigidbody_check_sim_running(RigidBodyWorld *rbw, float ctime)
   return (rbw && (rbw->flag & RBW_FLAG_MUTED) == 0 && ctime > rbw->shared->pointcache->startframe);
 }
 
-/* Sync rigid body and object transformations */
-void BKE_rigidbody_sync_transforms(RigidBodyWorld *rbw, Object *ob, float ctime)
+bool BKE_rigidbody_is_affected_by_simulation(Object *ob)
 {
-  RigidBodyOb *rbo = ob->rigidbody_object;
+  /* Check if the object will have its transform changed by the rigidbody simulation. */
 
   /* True if the shape of this object's parent is of type compound */
   bool obCompoundParent = (ob->parent != NULL && ob->parent->rigidbody_object != NULL &&
                            ob->parent->rigidbody_object->shape == RB_SHAPE_COMPOUND);
 
-  /* keep original transform for kinematic and passive objects */
-  if (ELEM(NULL, rbw, rbo) || rbo->flag & RBO_FLAG_KINEMATIC || rbo->type == RBO_TYPE_PASSIVE ||
+  RigidBodyOb *rbo = ob->rigidbody_object;
+  if (rbo == NULL || rbo->flag & RBO_FLAG_KINEMATIC || rbo->type == RBO_TYPE_PASSIVE ||
       obCompoundParent) {
+    return false;
+  }
+
+  return true;
+}
+
+/* Sync rigid body and object transformations */
+void BKE_rigidbody_sync_transforms(RigidBodyWorld *rbw, Object *ob, float ctime)
+{
+  if (!BKE_rigidbody_is_affected_by_simulation(ob)) {
+    /* Don't sync transforms for objects that are not affected/changed by the simulation. */
     return;
   }
 
+  RigidBodyOb *rbo = ob->rigidbody_object;
+
   /* use rigid body transform after cache start frame if objects is not being transformed */
   if (BKE_rigidbody_check_sim_running(rbw, ctime) &&
       !(ob->base_flag & BASE_SELECTED && G.moving & G_TRANSFORM_OBJ)) {
@@ -1941,8 +1953,8 @@ void BKE_rigidbody_sync_transforms(RigidBodyWorld *rbw, Object *ob, float ctime)
 void BKE_rigidbody_aftertrans_update(
     Object *ob, float loc[3], float rot[3], float quat[4], float rotAxis[3], float rotAngle)
 {
+  bool correct_delta = BKE_rigidbody_is_affected_by_simulation(ob);
   RigidBodyOb *rbo = ob->rigidbody_object;
-  bool correct_delta = !(rbo->flag & RBO_FLAG_KINEMATIC || rbo->type == RBO_TYPE_PASSIVE);
 
   /* return rigid body and object to their initial states */
   copy_v3_v3(rbo->pos, ob->loc);