added offset for plane mesh and quad mesh

doc/classes/PlaneMesh.xml

@@ -12,6 +12,9 @@
 	<methods>
 	</methods>
 	<members>
+		<member name="center_offset" type="Vector3" setter="set_center_offset" getter="get_center_offset" default="Vector3( 0, 0, 0 )">
+			Offset from the origin of the generated plane. Useful for particles.
+		</member>
 		<member name="size" type="Vector2" setter="set_size" getter="get_size" default="Vector2( 2, 2 )">
 			Size of the generated plane.
 		</member>

doc/classes/QuadMesh.xml

@@ -13,6 +13,9 @@
 	<methods>
 	</methods>
 	<members>
+		<member name="center_offset" type="Vector3" setter="set_center_offset" getter="get_center_offset" default="Vector3( 0, 0, 0 )">
+			Offset of the generated Quad. Useful for particles.
+		</member>
 		<member name="size" type="Vector2" setter="set_size" getter="get_size" default="Vector2( 1, 1 )">
 			Size on the X and Y axes.
 		</member>

scene/resources/primitive_meshes.cpp

@@ -982,7 +982,7 @@ void PlaneMesh::_create_mesh_array(Array &p_arr) const {
 			u /= (subdivide_w + 1.0);
 			v /= (subdivide_d + 1.0);
 
-			points.push_back(Vector3(-x, 0.0, -z));
+			points.push_back(Vector3(-x, 0.0, -z) + center_offset);
 			normals.push_back(Vector3(0.0, 1.0, 0.0));
 			ADD_TANGENT(1.0, 0.0, 0.0, 1.0);
 			uvs.push_back(Vector2(1.0 - u, 1.0 - v)); /* 1.0 - uv to match orientation with Quad */
@@ -1020,10 +1020,13 @@ void PlaneMesh::_bind_methods() {
 	ClassDB::bind_method(D_METHOD("get_subdivide_width"), &PlaneMesh::get_subdivide_width);
 	ClassDB::bind_method(D_METHOD("set_subdivide_depth", "subdivide"), &PlaneMesh::set_subdivide_depth);
 	ClassDB::bind_method(D_METHOD("get_subdivide_depth"), &PlaneMesh::get_subdivide_depth);
+	ClassDB::bind_method(D_METHOD("set_center_offset", "offset"), &PlaneMesh::set_center_offset);
+	ClassDB::bind_method(D_METHOD("get_center_offset"), &PlaneMesh::get_center_offset);
 
 	ADD_PROPERTY(PropertyInfo(Variant::VECTOR2, "size"), "set_size", "get_size");
 	ADD_PROPERTY(PropertyInfo(Variant::INT, "subdivide_width", PROPERTY_HINT_RANGE, "0,100,1,or_greater"), "set_subdivide_width", "get_subdivide_width");
 	ADD_PROPERTY(PropertyInfo(Variant::INT, "subdivide_depth", PROPERTY_HINT_RANGE, "0,100,1,or_greater"), "set_subdivide_depth", "get_subdivide_depth");
+	ADD_PROPERTY(PropertyInfo(Variant::VECTOR3, "center_offset"), "set_center_offset", "get_center_offset");
 }
 
 void PlaneMesh::set_size(const Size2 &p_size) {
@@ -1053,11 +1056,21 @@ int PlaneMesh::get_subdivide_depth() const {
 	return subdivide_d;
 }
 
+void PlaneMesh::set_center_offset(const Vector3 p_offset) {
+	center_offset = p_offset;
+	_request_update();
+}
+
+Vector3 PlaneMesh::get_center_offset() const {
+	return center_offset;
+}
+
 PlaneMesh::PlaneMesh() {
 	// defaults
 	size = Size2(2.0, 2.0);
 	subdivide_w = 0;
 	subdivide_d = 0;
+	center_offset = Vector3(0.0, 0.0, 0.0);
 }
 
 /**
@@ -1365,10 +1378,10 @@ void QuadMesh::_create_mesh_array(Array &p_arr) const {
 	Vector2 _size = Vector2(size.x / 2.0f, size.y / 2.0f);
 
 	Vector3 quad_faces[4] = {
-		Vector3(-_size.x, -_size.y, 0),
+		Vector3(-_size.x, -_size.y, 0) + center_offset,
-		Vector3(-_size.x, _size.y, 0),
+		Vector3(-_size.x, _size.y, 0) + center_offset,
-		Vector3(_size.x, _size.y, 0),
+		Vector3(_size.x, _size.y, 0) + center_offset,
-		Vector3(_size.x, -_size.y, 0),
+		Vector3(_size.x, -_size.y, 0) + center_offset,
 	};
 
 	static const int indices[6] = {
@@ -1404,12 +1417,17 @@ void QuadMesh::_create_mesh_array(Array &p_arr) const {
 void QuadMesh::_bind_methods() {
 	ClassDB::bind_method(D_METHOD("set_size", "size"), &QuadMesh::set_size);
 	ClassDB::bind_method(D_METHOD("get_size"), &QuadMesh::get_size);
+	ClassDB::bind_method(D_METHOD("set_center_offset", "center_offset"), &QuadMesh::set_center_offset);
+	ClassDB::bind_method(D_METHOD("get_center_offset"), &QuadMesh::get_center_offset);
+
 	ADD_PROPERTY(PropertyInfo(Variant::VECTOR2, "size"), "set_size", "get_size");
+	ADD_PROPERTY(PropertyInfo(Variant::VECTOR3, "center_offset"), "set_center_offset", "get_center_offset");
 }
 
 QuadMesh::QuadMesh() {
 	primitive_type = PRIMITIVE_TRIANGLES;
 	size = Size2(1.0, 1.0);
+	center_offset = Vector3(0.0, 0.0, 0.0);
 }
 
 void QuadMesh::set_size(const Size2 &p_size) {
@@ -1421,6 +1439,15 @@ Size2 QuadMesh::get_size() const {
 	return size;
 }
 
+void QuadMesh::set_center_offset(Vector3 p_center_offset) {
+	center_offset = p_center_offset;
+	_request_update();
+}
+
+Vector3 QuadMesh::get_center_offset() const {
+	return center_offset;
+}
+
 /**
   SphereMesh
 */

scene/resources/primitive_meshes.h

@@ -205,6 +205,7 @@ private:
 	Size2 size;
 	int subdivide_w;
 	int subdivide_d;
+	Vector3 center_offset;
 
 protected:
 	static void _bind_methods();
@@ -220,6 +221,9 @@ public:
 	void set_subdivide_depth(const int p_divisions);
 	int get_subdivide_depth() const;
 
+	void set_center_offset(const Vector3 p_offset);
+	Vector3 get_center_offset() const;
+
 	PlaneMesh();
 };
 
@@ -268,6 +272,7 @@ class QuadMesh : public PrimitiveMesh {
 
 private:
 	Size2 size;
+	Vector3 center_offset;
 
 protected:
 	static void _bind_methods();
@@ -278,6 +283,9 @@ public:
 
 	void set_size(const Size2 &p_size);
 	Size2 get_size() const;
+
+	void set_center_offset(const Vector3 p_offset);
+	Vector3 get_center_offset() const;
 };
 
 /**