Function render_thread_main 

pub fn render_thread_main(
    handles: WindowHandles,
    flags: EngineFlags,
    initial_pipeline: PipelineFactory,
    triple_buf: Arc<TripleBuffer<RWorld>>,
    frame_stats: FrameStats,
    cmd_rx: Receiver<RenderCommand>,
    upload_rx: Receiver<GpuUploadRequest>,
    ready_tx: SyncSender<()>,
)