From 342c88841d71119272f22302d50d74b130bb50f1 Mon Sep 17 00:00:00 2001
From: asheraryam <asheraryam@gmail.com>
Date: Thu, 30 Apr 2020 02:51:43 +0300
Subject: [PATCH] Create bindings for creating multiple-convex-collision static
 bodies from gdscript

---
 doc/classes/MeshInstance.xml |  7 +++++++
 scene/3d/mesh_instance.cpp   | 38 ++++++++++++++++++++++++++++++++++++
 scene/3d/mesh_instance.h     |  3 +++
 3 files changed, 48 insertions(+)

diff --git a/doc/classes/MeshInstance.xml b/doc/classes/MeshInstance.xml
index 70e02461a04..6f6d585fdc3 100644
--- a/doc/classes/MeshInstance.xml
+++ b/doc/classes/MeshInstance.xml
@@ -27,6 +27,13 @@
 				This helper creates a [MeshInstance] child node with gizmos at every vertex calculated from the mesh geometry. It's mainly used for testing.
 			</description>
 		</method>
+		<method name="create_multiple_convex_collisions">
+			<return type="void">
+			</return>
+			<description>
+				This helper creates a [StaticBody] child node with multiple [ConvexPolygonShape] collision shapes calculated from the mesh geometry via convex decomposition. It's mainly used for testing.
+			</description>
+		</method>
 		<method name="create_trimesh_collision">
 			<return type="void">
 			</return>
diff --git a/scene/3d/mesh_instance.cpp b/scene/3d/mesh_instance.cpp
index 1e6886c148e..177226c1436 100644
--- a/scene/3d/mesh_instance.cpp
+++ b/scene/3d/mesh_instance.cpp
@@ -573,6 +573,42 @@ void MeshInstance::create_trimesh_collision() {
 	}
 }
 
+Node *MeshInstance::create_multiple_convex_collisions_node() {
+
+	if (mesh.is_null())
+		return NULL;
+
+	Vector<Ref<Shape> > shapes = mesh->convex_decompose();
+	if (!shapes.size()) {
+		return NULL;
+	}
+
+	StaticBody *static_body = memnew(StaticBody);
+	for (int i = 0; i < shapes.size(); i++) {
+		CollisionShape *cshape = memnew(CollisionShape);
+		cshape->set_shape(shapes[i]);
+		static_body->add_child(cshape);
+	}
+	return static_body;
+}
+
+void MeshInstance::create_multiple_convex_collisions() {
+
+	StaticBody *static_body = Object::cast_to<StaticBody>(create_multiple_convex_collisions_node());
+	ERR_FAIL_COND(!static_body);
+	static_body->set_name(String(get_name()) + "_col");
+
+	add_child(static_body);
+	if (get_owner()) {
+		static_body->set_owner(get_owner());
+		int count = static_body->get_child_count();
+		for (int i = 0; i < count; i++) {
+			CollisionShape *cshape = Object::cast_to<CollisionShape>(static_body->get_child(i));
+			cshape->set_owner(get_owner());
+		}
+	}
+}
+
 Node *MeshInstance::create_convex_collision_node() {
 
 	if (mesh.is_null())
@@ -803,6 +839,8 @@ void MeshInstance::_bind_methods() {
 
 	ClassDB::bind_method(D_METHOD("create_trimesh_collision"), &MeshInstance::create_trimesh_collision);
 	ClassDB::set_method_flags("MeshInstance", "create_trimesh_collision", METHOD_FLAGS_DEFAULT);
+	ClassDB::bind_method(D_METHOD("create_multiple_convex_collisions"), &MeshInstance::create_multiple_convex_collisions);
+	ClassDB::set_method_flags("MeshInstance", "create_multiple_convex_collisions", METHOD_FLAGS_DEFAULT);
 	ClassDB::bind_method(D_METHOD("create_convex_collision"), &MeshInstance::create_convex_collision);
 	ClassDB::set_method_flags("MeshInstance", "create_convex_collision", METHOD_FLAGS_DEFAULT);
 	ClassDB::bind_method(D_METHOD("_mesh_changed"), &MeshInstance::_mesh_changed);
diff --git a/scene/3d/mesh_instance.h b/scene/3d/mesh_instance.h
index 151dbd60194..4b55ec0e8b6 100644
--- a/scene/3d/mesh_instance.h
+++ b/scene/3d/mesh_instance.h
@@ -127,6 +127,9 @@ public:
 	Node *create_trimesh_collision_node();
 	void create_trimesh_collision();
 
+	Node *create_multiple_convex_collisions_node();
+	void create_multiple_convex_collisions();
+
 	Node *create_convex_collision_node();
 	void create_convex_collision();