def _register_defines(self):
        """ Registers all the command types as defines so they can be used
        in a shader later on """
        for attr in dir(GPUCommand):
            if attr.startswith("CMD_"):
                attr_val = getattr(GPUCommand, attr)
                self._pipeline.stage_mgr.defines[attr] = attr_val
        self._pipeline.stage_mgr.defines["GPU_CMD_INT_AS_FLOAT"] = \
            GPUCommand.get_uses_integer_packing()
 Registers all the command types as defines so they can be used
        in a shader later on 
metadrive/render_pipeline/rpcore/gpu_command_queue.py