Function gvr_sys::gvr_buffer_viewport_set_external_surface_id

pub unsafe extern "C" fn gvr_buffer_viewport_set_external_surface_id(
    viewport: *mut gvr_buffer_viewport, 
    external_surface_id: i32
)

Sets the ID of the externally-managed Surface texture from which this viewport reads. The ID is issued by GvrLayout.

@param viewport The buffer viewport. @param external_surface_id The ID of the surface to read from.