Depsgraph: Add utility function for transform dependency

This is what modifiers are to use to indicate that they depend
on a transformation of the object itself.

Currently should be no functional changes, but in the future
this will allow to easily change transform operation depending
on whether there is a simulation associated with the object.

4 files changed, 46 insertions, 2 deletions

diff --git a/source/blender/depsgraph/DEG_depsgraph_build.h b/source/blender/depsgraph/DEG_depsgraph_build.h
index 0d90f64a37b..fe18193aac7 100644
--- a/source/blender/depsgraph/DEG_depsgraph_build.h
+++ b/source/blender/depsgraph/DEG_depsgraph_build.h
@@ -142,9 +142,18 @@ void DEG_add_generic_id_relation(struct DepsNodeHandle *node_handle,
                                  struct ID *id,
                                  const char *description);
 
+/* Special function which is used from modifiers' updateDepsgraph() callback
+ * to indicate that the modifietr needs to know transformation of the object
+ * which that modifier belongs to.
+ * This function will take care of checking which operation is required to
+ * have transformation for the modifier, taking into account possible simulation
+ * solvers. */
+void DEG_add_modifier_to_transform_relation(
+        struct DepsNodeHandle *node_handle,
+        const char *description);
+
 /* Adds relations from the given component of a given object to the given node
- * handle AND the component to the point cache component of the node's ID.
- */
+ * handle AND the component to the point cache component of the node's ID. */
 void DEG_add_object_pointcache_relation(struct DepsNodeHandle *node_handle,
                                         struct Object *object,
                                         eDepsObjectComponentType component,
diff --git a/source/blender/depsgraph/intern/builder/deg_builder_relations.cc b/source/blender/depsgraph/intern/builder/deg_builder_relations.cc
index c62fc604f94..0888105c248 100644
--- a/source/blender/depsgraph/intern/builder/deg_builder_relations.cc
+++ b/source/blender/depsgraph/intern/builder/deg_builder_relations.cc
@@ -278,6 +278,25 @@ bool DepsgraphRelationBuilder::has_node(const OperationKey &key) const
 	return find_node(key) != NULL;
 }
 
+void DepsgraphRelationBuilder::add_modifier_to_transform_relation(
+        const DepsNodeHandle *handle,
+        const char *description)
+{
+	/* Geometry operation, this is where relation will be wired to. */
+	OperationNode *geometry_operation_node =
+	        handle->node->get_entry_operation();
+	BLI_assert(geometry_operation_node->owner->type == NodeType::GEOMETRY);
+	/* Transform operation, the source of the relation. */
+	ID *id = geometry_operation_node->owner->owner->id_orig;
+	ComponentKey transform_component_key(id, NodeType::TRANSFORM);
+	Node *transform_node = get_node(transform_component_key);
+	OperationNode *transform_operation_node =
+	        transform_node->get_exit_operation();
+	/* Wire up the actual relation. */
+	add_operation_relation(
+	        transform_operation_node, geometry_operation_node, description);
+}
+
 void DepsgraphRelationBuilder::add_customdata_mask(Object *object, uint64_t mask)
 {
 	if (mask != 0 && object != NULL && object->type == OB_MESH) {
diff --git a/source/blender/depsgraph/intern/builder/deg_builder_relations.h b/source/blender/depsgraph/intern/builder/deg_builder_relations.h
index 8765a8a5eb4..de39f624290 100644
--- a/source/blender/depsgraph/intern/builder/deg_builder_relations.h
+++ b/source/blender/depsgraph/intern/builder/deg_builder_relations.h
@@ -194,6 +194,12 @@ struct DepsgraphRelationBuilder
 	                                   const char *description,
 	                                   int flags = 0);
 
+	/* Adds relation from proper transformation opertation to the modifier.
+	 * Takes care of checking for possible physics solvers modifying position
+	 * of this object. */
+	void add_modifier_to_transform_relation(const DepsNodeHandle *handle,
+	                                        const char *description);
+
 	void add_customdata_mask(Object *object, uint64_t mask);
 	void add_special_eval_flag(ID *object, uint32_t flag);
 
diff --git a/source/blender/depsgraph/intern/depsgraph_build.cc b/source/blender/depsgraph/intern/depsgraph_build.cc
index e44a98518d1..8720e407681 100644
--- a/source/blender/depsgraph/intern/depsgraph_build.cc
+++ b/source/blender/depsgraph/intern/depsgraph_build.cc
@@ -190,6 +190,16 @@ void DEG_add_generic_id_relation(struct DepsNodeHandle *node_handle,
 	                                                   description);
 }
 
+void DEG_add_modifier_to_transform_relation(
+        struct DepsNodeHandle *node_handle,
+        const char *description)
+{
+	DEG::DepsNodeHandle *deg_node_handle = get_node_handle(node_handle);
+	deg_node_handle->builder->add_modifier_to_transform_relation(
+	        deg_node_handle,
+	        description);
+}
+
 void DEG_add_special_eval_flag(struct DepsNodeHandle *node_handle,
                                ID *id,
                                uint32_t flag)