超详细介绍Unity中的Command Buffers

Command Buffer简介

首先附加官方文档介绍：Command Buffer简介
Command Buffer 是一个保存渲染命令的缓冲区（内存块），我们可以使用它对渲染管线进行扩展，在渲染管线指定的某几个阶段插入这个渲染命令，以达到想要的效果。Command Buffer可以实现多种后效及特效，常用于对某个模型做二次渲染。
Command Buffer可以插入到渲染管线的以下节点位置：

以上节点可从Camera Event和Light Event获取：

CameraEvent和LightEvent

CameraEvent和LightEvent用于指定Command Buffer 插入的位置，分别对应camera和light：

CameraEvent

Properties

BeforeDepthTexture	Before camera's depth texture is generated.
AfterDepthTexture	After camera's depth texture is generated.
BeforeDepthNormalsTexture	Before camera's depth+normals texture is generated.
AfterDepthNormalsTexture	After camera's depth+normals texture is generated.
BeforeGBuffer	Before deferred rendering G-buffer is rendered.
AfterGBuffer	After deferred rendering G-buffer is rendered.
BeforeLighting	Before lighting pass in deferred rendering.
AfterLighting	After lighting pass in deferred rendering.
BeforeFinalPass	Before final geometry pass in deferred lighting.
AfterFinalPass	After final geometry pass in deferred lighting.
BeforeForwardOpaque	Before opaque objects in forward rendering.
AfterForwardOpaque	After opaque objects in forward rendering.
BeforeImageEffectsOpaque	Before image effects that happen between opaque & transparent objects.
AfterImageEffectsOpaque	After image effects that happen between opaque & transparent objects.
BeforeSkybox	Before skybox is drawn.
AfterSkybox	After skybox is drawn.
BeforeForwardAlpha	Before transparent objects in forward rendering.
AfterForwardAlpha	After transparent objects in forward rendering.
BeforeImageEffects	Before image effects.
AfterImageEffects	After image effects.
AfterEverything	After camera has done rendering everything.
BeforeReflections	Before reflections pass in deferred rendering.
AfterReflections	After reflections pass in deferred rendering.
BeforeHaloAndLensFlares	Before halo and lens flares.
AfterHaloAndLensFlares	After halo and lens flares.

LightEvent

BeforeShadowMap	Before shadowmap is rendered.
AfterShadowMap	After shadowmap is rendered.
BeforeScreenspaceMask	Before directional light screenspace shadow mask is computed.
AfterScreenspaceMask	After directional light screenspace shadow mask is computed.
BeforeShadowMapPass	Before shadowmap pass is rendered.
AfterShadowMapPass	After shadowmap pass is rendered.

测试程序

       public Camera  m_camera;
		public void AddCommandBuffer(CommandBuffer commandBuffer)
		{
			//m_camera.RemoveCommandBuffer(CameraEvent.BeforeImageEffectsOpaque, commandBuffer); // 以防万一
			m_camera.AddCommandBuffer(CameraEvent.AfterForwardOpaque,commandBuffer);
		}
		public Shader shader;
		void start()
		{
		CommandBuffer buffer = new CommandBuffer();
        //设置自己的渲染,使用该shader在渲染不透明物体之前，再渲染一次物体本身
        buffer.DrawRenderer(GetComponent<Renderer>(), new Material(shader));
        AddCommandBuffer(buffer);
		}