Make texture parameter optional in begin() of ImmediateGeometry. Closes #5676 and closes #5720

scene/3d/immediate_geometry.cpp

@@ -149,7 +149,7 @@ void ImmediateGeometry::add_sphere(int p_lats,int p_lons,float p_radius) {
 
 void ImmediateGeometry::_bind_methods() {
 
-	ObjectTypeDB::bind_method(_MD("begin","primitive","texture:Texture"),&ImmediateGeometry::begin);
+	ObjectTypeDB::bind_method(_MD("begin","primitive","texture:Texture"),&ImmediateGeometry::begin,DEFVAL(Ref<Texture>()));
 	ObjectTypeDB::bind_method(_MD("set_normal","normal"),&ImmediateGeometry::set_normal);
 	ObjectTypeDB::bind_method(_MD("set_tangent","tangent"),&ImmediateGeometry::set_tangent);
 	ObjectTypeDB::bind_method(_MD("set_color","color"),&ImmediateGeometry::set_color);

scene/3d/immediate_geometry.h

@@ -47,7 +47,7 @@ protected:
 public:
 
 
-	void begin(Mesh::PrimitiveType p_primitive,const Ref<Texture>& p_texture);
+	void begin(Mesh::PrimitiveType p_primitive,const Ref<Texture>& p_texture=Ref<Texture>());
 	void set_normal(const Vector3& p_normal);
 	void set_tangent(const Plane& p_tangent);
 	void set_color(const Color& p_color);