[Unity]动态修改URP资源的相关参数

一、获取当前的UniversalRenderPipelineAsset

工程里UniversalRenderPipelineAsset可能有好几种（比如low、mid、high等），游戏运行时会根据机型动态加载指定的UniversalRenderPipelineAsset，以下代码可以动态获取当前使用的UniversalRenderPipelineAsset具体是哪个，然后动态修改阴影等别的参数：

UniversalRenderPipelineAsset m_URPAsset = GraphicsSettings.currentRenderPipeline as UniversalRenderPipelineAsset;
        if (m_URPAsset != null)
        {
            m_DefaultDistance = m_URPAsset.shadowDistance;
            m_URPAsset.shadowDistance = m_ShadowDistance;
        }

二、一个坑

上面代码在Start函数里只能获取默认的UniversalRenderPipelineAsset，而不是当前实际运行的UniversalRenderPipelineAsset，我这边的做法是在协程里等了一帧去获取：

private IEnumerator IEResetShadows()
    {
        //第一帧的时候获取的是默认的pipeline
        yield return null;
        // 动态设置阴影距离
        UniversalRenderPipelineAsset m_URPAsset = GraphicsSettings.currentRenderPipeline as UniversalRenderPipelineAsset;
        if (m_URPAsset != null)
        {
            m_DefaultDistance = m_URPAsset.shadowDistance;
            m_URPAsset.shadowDistance = m_ShadowDistance;
        }
    }