public ForwardRenderer(ForwardRendererData data) : base(data)
{
  // 绘制不透明物件
  m_RenderOpaqueForwardPass = new DrawObjectsPass("Render Opaques", true, RenderPassEvent.BeforeRenderingOpaques, RenderQueueRange.opaque, data.opaqueLayerMask, m_DefaultStencilState, stencilData.stencilReference);
  // 绘制透明物件
m_RenderTransparentForwardPass = new DrawObjectsPass("Render Transparents", false, RenderPassEvent.BeforeRenderingTransparents, RenderQueueRange.transparent, data.transparentLayerMask, m_DefaultStencilState, stencilData.stencilReference);


...


public DrawObjectsPass(string profilerTag, bool opaque, RenderPassEvent evt, RenderQueueRange renderQueueRange, LayerMask layerMask, StencilState stencilState, int stencilReference)
{
    m_ProfilerTag = profilerTag;
    m_ProfilingSampler = new ProfilingSampler(profilerTag);
    m_ShaderTagIdList.Add(new ShaderTagId("UniversalForward"));
    m_ShaderTagIdList.Add(new ShaderTagId("LightweightForward"));
    m_ShaderTagIdList.Add(new ShaderTagId("SRPDefaultUnlit"));
    renderPassEvent = evt;
    m_FilteringSettings = new FilteringSettings(renderQueueRange, layerMask);
    m_RenderStateBlock = new RenderStateBlock(RenderStateMask.Nothing);
    m_IsOpaque = opaque;

    if (stencilState.enabled)
    {
        m_RenderStateBlock.stencilReference = stencilReference;
        m_RenderStateBlock.mask = RenderStateMask.Stencil;
        m_RenderStateBlock.stencilState = stencilState;
    }
}

public override void Execute(ScriptableRenderContext context, ref RenderingData renderingData)
{
    CommandBuffer cmd = CommandBufferPool.Get(m_ProfilerTag);
    using (new ProfilingScope(cmd, m_ProfilingSampler))
    {
        context.ExecuteCommandBuffer(cmd);
        cmd.Clear();

        Camera camera = renderingData.cameraData.camera;
        var sortFlags = (m_IsOpaque) ? renderingData.cameraData.defaultOpaqueSortFlags : SortingCriteria.CommonTransparent;
        var drawSettings = CreateDrawingSettings(m_ShaderTagIdList, ref renderingData, sortFlags);
        context.DrawRenderers(renderingData.cullResults, ref drawSettings, ref m_FilteringSettings, ref m_RenderStateBlock);

        // Render objects that did not match any shader pass with error shader
        RenderingUtils.RenderObjectsWithError(context, ref renderingData.cullResults, camera, m_FilteringSettings, SortingCriteria.None);
    }
    context.ExecuteCommandBuffer(cmd);
    CommandBufferPool.Release(cmd);
}


// ...


public DrawingSettings CreateDrawingSettings(List<ShaderTagId> shaderTagIdList,
    ref RenderingData renderingData, SortingCriteria sortingCriteria)
{
    if (shaderTagIdList == null || shaderTagIdList.Count == 0)
    {
        Debug.LogWarning("ShaderTagId list is invalid. DrawingSettings is created with default pipeline ShaderTagId");
        return CreateDrawingSettings(new ShaderTagId("UniversalPipeline"), ref renderingData, sortingCriteria);
    }

    DrawingSettings settings = CreateDrawingSettings(shaderTagIdList[0], ref renderingData, sortingCriteria);
    for (int i = 1; i < shaderTagIdList.Count; ++i)
        settings.SetShaderPassName(i, shaderTagIdList[i]);
    return settings;
}