func _process(delta):
    simulate_fps += delta
    if simulate_fps > (1.0 / target_fps):
        simulate_fps = 0.0
        render_target_update_mode = Viewport.UPDATE_ONCE

        # might not be set yet
        var texture = $VRPreview.texture
        if texture:
            var textSize = texture.get_size()
            var textSCale = size.x / textSize.x
            $VRPreview.rect_size = textSize*textSCale
            $VRPreview.rect_position = (size - $VRPreview.rect_size)*0.5