unity MRT(渲染到多個目標)

1. 
   

   轉載：http://forum.unity3d.com/threads/152050-MRT-example?p=1118431&viewfull=1#post1118431

   Unity--延遲渲染
   延遲渲染就是將相機視野中的物體渲染到屏幕之前對這些物體數據進行處理。這些數據可以是法線、位置等。
   unity中我們可以在OnPreRender() 函數中去設置相機渲染方式，我們可以看一下Graphics.SetRenderTarget(....)函數的使用。setRenderTarget後，我們可以在shader中取出我們所需要的法線、位置等信息。這樣在OnRenderImage()函數中我們就可以對這些數據進行處理或直接顯示在屏幕上。
   

   
   

   MRT example?

   Posted: 03:33 PM 09-21-2012

   Does anyone have a simple example of MRT's with ImageEffects? 
   
   I really can't seem to get it to work  
   
   I tried it with SetRenderBuffer and Blit:
   
   

   Code:  

   1.     void OnRenderImage (RenderTexture source, RenderTexture destination)
   2.     {      
   3.        
   4.         RenderTexture meanCol = RenderTexture.GetTemporary(source.width, source.height);
   5.         RenderTexture meanPos = RenderTexture.GetTemporary(source.width, source.height);
   6.        
   7.         //MeanShiftMaterial().SetTexture("_MainTex",source);       
   8.        
   9.         RenderBuffer[] buffers = new RenderBuffer[2];
   10.         buffers[0] = meanCol.colorBuffer;
   11.         buffers[1] = meanPos.colorBuffer;
   12.        
   13.         Graphics.SetRenderTarget(buffers,meanCol.depthBuffer);     
   14.         Graphics.Blit(source,meanCol,MeanShiftMaterial(),0);
   15. }

   
   Doesn't work. 
   
   I tried it with Graphics.DrawTexture, nothing.
   
   Any help hugely appreciated!
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2. epifire 

   Posts

   1

   Posted: 07:41 PM 12-23-2012

   You can't use the Graphics.Blit since it only set one RenderTexture internally.
   When using MRT, you have to render the full screen quad manually for Blit.
   Here's a simple example:
   
   

   Code:  

   1. using UnityEngine;
   2. using System.Collections;
   3.  
   4. [ExecuteInEditMode]
   5. [RequireComponent(typeof(Camera))]
   6.  
   7. public class TestMRT : PostEffectsBase
   8. {
   9.     private Material testMRTMaterial = null;
   10.     private RenderTexture[] mrtTex = new RenderTexture[2];
   11.     private RenderBuffer[] mrtRB = new RenderBuffer[2];
   12.  
   13.     void Start ()
   14.     {
   15.         mrtTex[0] = new RenderTexture(Screen.width, Screen.height, 24, RenderTextureFormat.ARGB32);
   16.         mrtTex[1] = new RenderTexture(Screen.width, Screen.height, 24, RenderTextureFormat.ARGB32);
   17.         mrtRB[0] = mrtTex[0].colorBuffer;
   18.         mrtRB[1] = mrtTex[1].colorBuffer;
   19.     }
   20.  
   21.     public override bool CheckResources()
   22.     {
   23.         CheckSupport(true);
   24.  
   25.         testMRTMaterial = CheckShaderAndCreateMaterial(Shader.Find("Custom/TestMRT"), testMRTMaterial);
   26.  
   27.         if (!isSupported)
   28.             ReportAutoDisable();
   29.         return isSupported;
   30.     }
   31.  
   32.     void OnRenderImage(RenderTexture source, RenderTexture destination)
   33.     {
   34.         if (CheckResources() == false)
   35.         {
   36.             Graphics.Blit(source, destination);
   37.             return;
   38.         }
   39.  
   40.         RenderTexture oldRT = RenderTexture.active;
   41.  
   42.         Graphics.SetRenderTarget(mrtRB, mrtTex[0].depthBuffer);
   43.  
   44.         GL.Clear(false, true, Color.clear);
   45.  
   46.         GL.PushMatrix();
   47.         GL.LoadOrtho();
   48.  
   49.         testMRTMaterial.SetPass(0);     //Pass 0 outputs 2 render textures.
   50.  
   51.         //Render the full screen quad manually.
   52.         GL.Begin(GL.QUADS);
   53.         GL.TexCoord2(0.0f, 0.0f); GL.Vertex3(0.0f, 0.0f, 0.1f);
   54.         GL.TexCoord2(1.0f, 0.0f); GL.Vertex3(1.0f, 0.0f, 0.1f);
   55.         GL.TexCoord2(1.0f, 1.0f); GL.Vertex3(1.0f, 1.0f, 0.1f);
   56.         GL.TexCoord2(0.0f, 1.0f); GL.Vertex3(0.0f, 1.0f, 0.1f);
   57.         GL.End();
   58.  
   59.         GL.PopMatrix();
   60.  
   61.         RenderTexture.active = oldRT;
   62.  
   63.         //Show the result
   64.         testMRTMaterial.SetTexture("_Tex0", mrtTex[0]);
   65.         testMRTMaterial.SetTexture("_Tex1", mrtTex[1]);
   66.         Graphics.Blit(source, destination, testMRTMaterial, 1);
   67.     }
   68. }

   
   And the shader code:
   
   

   Code:  

   1. Shader "Custom/TestMRT" {
   2.     Properties {
   3.         _MainTex ("", 2D) = "" {}
   4.     }
   5.    
   6.     CGINCLUDE
   7.    
   8.     #include "UnityCG.cginc"
   9.      
   10.     struct v2f {
   11.         float4 pos : POSITION;
   12.         float2 uv : TEXCOORD0;
   13.     };
   14.    
   15.     struct PixelOutput {
   16.         float4 col0 : COLOR0;
   17.         float4 col1 : COLOR1;
   18.     };
   19.    
   20.     sampler2D _MainTex;
   21.     sampler2D _Tex0;
   22.     sampler2D _Tex1;
   23.    
   24.     v2f vert( appdata_img v )
   25.     {
   26.         v2f o;
   27.         o.pos = mul(UNITY_MATRIX_MVP, v.vertex);
   28.         o.uv = v.texcoord.xy;
   29.         return o;
   30.     }
   31.    
   32.     PixelOutput fragTestMRT(v2f pixelData)
   33.     {
   34.         PixelOutput o;
   35.         o.col0 = float4(1.0f, 0.0f, 0.0f, 1.0f);
   36.         o.col1 = float4(0.0f, 1.0f, 0.0f, 1.0f);
   37.         return o;
   38.     }
   39.    
   40.     float4 fragShowMRT(v2f pixelData) : COLOR0
   41.     {
   42.         return tex2D(_Tex0, pixelData.uv);
   43.         //return tex2D(_Tex1, pixelData.uv);
   44.     }
   45.    
   46.     ENDCG
   47.    
   48. Subshader {
   49.  Pass {
   50.       ZTest Always Cull Off ZWrite Off
   51.       Fog { Mode off }
   52.  
   53.       CGPROGRAM
   54.       #pragma glsl
   55.       #pragma fragmentoption ARB_precision_hint_fastest
   56.       #pragma vertex vert
   57.       #pragma fragment fragTestMRT
   58.       #pragma target 3.0
   59.       ENDCG
   60.   }
   61.  Pass {
   62.       ZTest Always Cull Off ZWrite Off
   63.       Fog { Mode off }
   64.  
   65.       CGPROGRAM
   66.       #pragma glsl
   67.       #pragma fragmentoption ARB_precision_hint_fastest
   68.       #pragma vertex vert
   69.       #pragma fragment fragShowMRT
   70.       #pragma target 3.0
   71.       ENDCG
   72.   }
   73. }
   74.  
   75. Fallback off
   76.    
   77. }