/// fd_rectangle_destroy(instance id);
function fd_rectangle_destroy(domain) {
	// Destroys a fluid dynamics rectangle.
	// instance id: The fluid dynamics rectangle to destroy.

	with (domain) {
	    surface_free(sf_pressure); surface_free(sf_pressure_temporary);
	    surface_free(sf_velocity); surface_free(sf_velocity_temporary);
	    surface_free(sf_material_0); surface_free(sf_material_0_temporary);
	    surface_free(sf_material_1); surface_free(sf_material_1_temporary);
	    surface_free(sf_world);
	    instance_destroy();
	}
}