Add Extras Dropdown Menu to Constraints

Add Apply Constraint, Duplicate Constraint, and Copy To Selected
operators, and include them in a menu similar to the menu for modifiers.
The shortcuts in the extras menu are also matched to modifiers.

All the here added operators are intended to work exactly like the
analogous ones for modifiers. That means the apply operator should apply
a constraint as if it was first in the list, just like modifiers do. I
have added the same warning message as for modifiers when that happens.

The decision to use this approach of appling the constraint as if it was
first, was made for consistency with modifiers. People are already used
to how it works there. Is also provides more intricate control over the
applied transforms, then just applying all constraints up to that one.
Apply all constraints is already kinda implemented in Bake Animation.

Reviewed By: HooglyBoogly, sybren, #user_interface

Differential Revision: https://developer.blender.org/D10914

2 files changed, 127 insertions, 0 deletions

diff --git a/source/blender/blenkernel/BKE_constraint.h b/source/blender/blenkernel/BKE_constraint.h
index 575df93a9fc..784b395dfa5 100644
--- a/source/blender/blenkernel/BKE_constraint.h
+++ b/source/blender/blenkernel/BKE_constraint.h
@@ -192,6 +192,28 @@ bool BKE_constraint_remove_ex(ListBase *list,
                               bool clear_dep);
 bool BKE_constraint_remove(ListBase *list, struct bConstraint *con);
 
+bool BKE_constraint_apply_for_object(struct Depsgraph *depsgraph,
+                                     struct Scene *scene,
+                                     struct Object *ob,
+                                     struct bConstraint *con);
+bool BKE_constraint_apply_and_remove_for_object(struct Depsgraph *depsgraph,
+                                                struct Scene *scene,
+                                                ListBase /*bConstraint*/ *constraints,
+                                                struct Object *ob,
+                                                struct bConstraint *con);
+
+bool BKE_constraint_apply_for_pose(struct Depsgraph *depsgraph,
+                                   struct Scene *scene,
+                                   struct Object *ob,
+                                   struct bPoseChannel *pchan,
+                                   struct bConstraint *con);
+bool BKE_constraint_apply_and_remove_for_pose(struct Depsgraph *depsgraph,
+                                              struct Scene *scene,
+                                              ListBase /*bConstraint*/ *constraints,
+                                              struct Object *ob,
+                                              struct bConstraint *con,
+                                              struct bPoseChannel *pchan);
+
 void BKE_constraint_panel_expand(struct bConstraint *con);
 
 /* Constraints + Proxies function prototypes */
diff --git a/source/blender/blenkernel/intern/constraint.c b/source/blender/blenkernel/intern/constraint.c
index 0da29ded13d..4b26022039e 100644
--- a/source/blender/blenkernel/intern/constraint.c
+++ b/source/blender/blenkernel/intern/constraint.c
@@ -5677,6 +5677,111 @@ bool BKE_constraint_remove_ex(ListBase *list, Object *ob, bConstraint *con, bool
   return false;
 }
 
+/* Apply the specified constraint in the given constraint stack */
+bool BKE_constraint_apply_for_object(Depsgraph *depsgraph,
+                                     Scene *scene,
+                                     Object *ob,
+                                     bConstraint *con)
+{
+  if (!con) {
+    return false;
+  }
+
+  const float ctime = BKE_scene_frame_get(scene);
+
+  bConstraint *new_con = BKE_constraint_duplicate_ex(con, 0, !ID_IS_LINKED(ob));
+  ListBase single_con = {new_con, new_con};
+
+  bConstraintOb *cob = BKE_constraints_make_evalob(
+      depsgraph, scene, ob, NULL, CONSTRAINT_OBTYPE_OBJECT);
+  /* Undo the effect of the current constraint stack evaluation. */
+  mul_m4_m4m4(cob->matrix, ob->constinv, cob->matrix);
+
+  /* Evaluate single constraint. */
+  BKE_constraints_solve(depsgraph, &single_con, cob, ctime);
+  /* Copy transforms back. This will leave the object in a bad state
+   * as ob->constinv will be wrong until next evaluation. */
+  BKE_constraints_clear_evalob(cob);
+
+  /* Free the copied constraint. */
+  BKE_constraint_free_data(new_con);
+  BLI_freelinkN(&single_con, new_con);
+
+  /* Apply transform from matrix. */
+  BKE_object_apply_mat4(ob, ob->obmat, true, true);
+
+  return true;
+}
+
+bool BKE_constraint_apply_and_remove_for_object(Depsgraph *depsgraph,
+                                                Scene *scene,
+                                                ListBase /*bConstraint*/ *constraints,
+                                                Object *ob,
+                                                bConstraint *con)
+{
+  if (!BKE_constraint_apply_for_object(depsgraph, scene, ob, con)) {
+    return false;
+  }
+
+  return BKE_constraint_remove_ex(constraints, ob, con, true);
+}
+
+bool BKE_constraint_apply_for_pose(
+    Depsgraph *depsgraph, Scene *scene, Object *ob, bPoseChannel *pchan, bConstraint *con)
+{
+  if (!con) {
+    return false;
+  }
+
+  const float ctime = BKE_scene_frame_get(scene);
+
+  bConstraint *new_con = BKE_constraint_duplicate_ex(con, 0, !ID_IS_LINKED(ob));
+  ListBase single_con;
+  single_con.first = new_con;
+  single_con.last = new_con;
+
+  float vec[3];
+  copy_v3_v3(vec, pchan->pose_mat[3]);
+
+  bConstraintOb *cob = BKE_constraints_make_evalob(
+      depsgraph, scene, ob, pchan, CONSTRAINT_OBTYPE_BONE);
+  /* Undo the effects of currently applied constraints. */
+  mul_m4_m4m4(cob->matrix, pchan->constinv, cob->matrix);
+  /* Evaluate single constraint. */
+  BKE_constraints_solve(depsgraph, &single_con, cob, ctime);
+  BKE_constraints_clear_evalob(cob);
+
+  /* Free the copied constraint. */
+  BKE_constraint_free_data(new_con);
+  BLI_freelinkN(&single_con, new_con);
+
+  /* Prevent constraints breaking a chain. */
+  if (pchan->bone->flag & BONE_CONNECTED) {
+    copy_v3_v3(pchan->pose_mat[3], vec);
+  }
+
+  /* Apply transform from matrix. */
+  float mat[4][4];
+  BKE_armature_mat_pose_to_bone(pchan, pchan->pose_mat, mat);
+  BKE_pchan_apply_mat4(pchan, mat, true);
+
+  return true;
+}
+
+bool BKE_constraint_apply_and_remove_for_pose(Depsgraph *depsgraph,
+                                              Scene *scene,
+                                              ListBase /*bConstraint*/ *constraints,
+                                              Object *ob,
+                                              bConstraint *con,
+                                              bPoseChannel *pchan)
+{
+  if (!BKE_constraint_apply_for_pose(depsgraph, scene, ob, pchan, con)) {
+    return false;
+  }
+
+  return BKE_constraint_remove_ex(constraints, ob, con, true);
+}
+
 void BKE_constraint_panel_expand(bConstraint *con)
 {
   con->ui_expand_flag |= UI_PANEL_DATA_EXPAND_ROOT;