Unity SRP 可编程渲染管线的基本用法

可编程渲染管线使用教程
SRP 可以处理Canvas为Screen Space - Overlay的渲染

安装插件

首先进入package manager，下载Core RP Lib组件

创建渲染管线

编写渲染管线逻辑脚本

新建脚本取名为MPipeLine，该脚本用于实现渲染管线的处理逻辑

using UnityEngine;
using UnityEngine.Rendering;public class MPipeLine : RenderPipeline
{public MPipeLine() { }protected override void Render(ScriptableRenderContext context, Camera[] cameras){// 创建渲染指令，默认填充白色var cmd = new CommandBuffer();cmd.ClearRenderTarget(true, true, Color.white);context.ExecuteCommandBuffer(cmd);cmd.Release();// 提交渲染指令context.Submit();}
}

编写渲染管线与编辑器关联

创建脚本MPipelineAsset，用于与unity编辑器建立关联，允许将工程与自定义渲染管线进行绑定

using UnityEngine;
using UnityEngine.Rendering;[CreateAssetMenu(menuName = "Rendering/MPipelineAsset")]
public class MPipelineAsset : RenderPipelineAsset
{protected override RenderPipeline CreatePipeline(){// 渲染逻辑脚本return new MPipeLine();}
}

创建并配置PipeLine Asset

首先创建Asset文件


点击Edit > projectsettings > graphics，设置asset为我们刚才新建的那个管线资源

编辑渲染管线逻辑

渲染逻辑有两种写法，一种是直接创建指令

    //var cmd = new CommandBuffer() { name = "clear" };//cmd.ClearRenderTarget(true, true, Color.white);//context.ExecuteCommandBuffer(cmd);//cmd.Release();//context.Submit();

另一种是调用渲染api来实现，所有的逻辑要包在Begin、end之间

    RenderPipeline.BeginFrameRendering(context, cameras);// 要渲染的相机Camera camera = cameras[0];// 相机渲染   不透明RenderCamera(context, camera, "shader1", SortingCriteria.CommonOpaque, RenderQueueRange.opaque);RenderCamera(context, camera, "shader2", SortingCriteria.CommonTransparent, RenderQueueRange.transparent);// 结束帧渲染你RenderPipeline.EndFrameRendering(context, cameras);

我们这里使用后者来分别创建透明、不透明、及天空盒的渲染逻辑

  protected override void Render(ScriptableRenderContext context, Camera[] cameras){// 开始帧渲染RenderPipeline.BeginFrameRendering(context, cameras);// 要渲染的相机Camera camera = cameras[0];// 相机渲染   不透明， shader1是自建shader，代码在后面RenderCamera(context, camera, "shader1", SortingCriteria.CommonOpaque, RenderQueueRange.opaque);// 相机渲染   不透明， shader2是自建shader，代码在后面RenderCamera(context, camera, "shader2", SortingCriteria.CommonTransparent, RenderQueueRange.transparent);// 结束帧渲染RenderPipeline.EndFrameRendering(context, cameras);}private void RenderCamera(ScriptableRenderContext context, Camera camera, string TagId, SortingCriteria criteria, RenderQueueRange queue){// 开始渲染摄像机RenderPipeline.BeginCameraRendering(context, camera);// Camera 区域剔除ScriptableCullingParameters cullingParameters = new ScriptableCullingParameters();cullingParameters.cullingOptions |= CullingOptions.OcclusionCull;// 剔除除了default layer之外的layercullingParameters.cullingMask = 1 << 0;camera.TryGetCullingParameters(out cullingParameters);var cullingResults = context.Cull(ref cullingParameters);// 更新当前摄像机内置着色器变量值context.SetupCameraProperties(camera);// DrawingSettings用来描述可见物体的排序方式，以及绘制使用的Shader PassShaderTagId shaderTagId = new ShaderTagId(TagId);var sortingSettings = new SortingSettings(camera) {criteria = criteria };DrawingSettings drawingSettings = new DrawingSettings(shaderTagId, sortingSettings);// 过滤  FilteringSettings用来描述渲染时如何过滤可见物体FilteringSettings filteringSettings = new FilteringSettings(queue);// 绘制图形context.DrawRenderers(cullingResults, ref drawingSettings, ref filteringSettings);// 绘制天空盒if (camera.clearFlags == CameraClearFlags.Skybox && RenderSettings.skybox != null && queue != RenderQueueRange.transparent){context.DrawSkybox(camera);}// 提交渲染按 context.Submit();// 结束渲染摄像机RenderPipeline.EndCameraRendering(context, camera);}

创建着色器

分别创建shader1.shader, shader2.shader两个着色器资源，并将下列代码填入
shader1：

Shader "Custom/mShader1"
{Properties{_MainTex ("Texture", 2D) = "white" {}}SubShader{Blend One OneMinusSrcAlphaPass{Tags { "LightMode"="shader1" }CGPROGRAM#pragma vertex vert#pragma fragment frag// make fog work#pragma multi_compile_fog#include "UnityCG.cginc"struct appdata{float4 vertex : POSITION;float2 uv : TEXCOORD0;};struct v2f{float2 uv : TEXCOORD0;UNITY_FOG_COORDS(1)float4 vertex : SV_POSITION;};sampler2D _MainTex;float4 _MainTex_ST;v2f vert (appdata v){v2f o;o.vertex = UnityObjectToClipPos(v.vertex);o.uv = TRANSFORM_TEX(v.uv, _MainTex);UNITY_TRANSFER_FOG(o,o.vertex);return o;}fixed4 frag (v2f i) : SV_Target{// sample the texturefixed4 col = tex2D(_MainTex, i.uv);// apply fogUNITY_APPLY_FOG(i.fogCoord, col);return col;}ENDCG}}
}

shader2:

Shader "Custom/mShader2"
{Properties{_MainTex ("Texture", 2D) = "#A84242" {}_MainColor("color", Color) = (1,1,1,1)}SubShader{Tags{"Queue" = "Transparent""RenderType"="Transparent""PreviewType"="Plane"}Cull Off//Lighting On //ZWrite OnBlend One OneMinusSrcAlphaPass{Tags { "LightMode"="shader2" }CGPROGRAM#pragma vertex vert#pragma fragment frag// make fog work#pragma multi_compile_fog#include "UnityCG.cginc"struct appdata{float4 vertex : POSITION;float2 uv : TEXCOORD0;};struct v2f{float2 uv : TEXCOORD0;UNITY_FOG_COORDS(1)float4 vertex : SV_POSITION;};sampler2D _MainTex;float4 _MainTex_ST;fixed4 _MainColor;v2f vert (appdata v){v2f o;o.vertex = UnityObjectToClipPos(v.vertex);o.uv = TRANSFORM_TEX(v.uv, _MainTex);UNITY_TRANSFER_FOG(o,o.vertex);return o;}fixed4 frag (v2f i) : SV_Target{// sample the texturefixed4 col = tex2D(_MainTex, i.uv) * _MainColor;// apply fog//UNITY_APPLY_FOG(i.fogCoord, col);col.a = _MainColor.a;return col;}ENDCG}}
}

测试效果

然后创建材质mat1.materil、mat2.materil。 mat1关联shader1，mat2关联shader2，将mat2的color透明度调到100

在场景中创建cube1和cube2两个方形物体，这时我们是什么都看不到的。

拖动cube2，一部分挡在cube1前面，并将mat1赋给cube1，mat2赋给cube2。此时我们就能看到自定义渲染管线生效了