MRT example?

Unity Engine
1

Does anyone have a simple example of MRT’s with ImageEffects?

I really can’t seem to get it to work :frowning:

I tried it with SetRenderBuffer and Blit:

	void OnRenderImage (RenderTexture source, RenderTexture destination)
	{		
		
		RenderTexture meanCol = RenderTexture.GetTemporary(source.width, source.height);
		RenderTexture meanPos = RenderTexture.GetTemporary(source.width, source.height);
		
		//MeanShiftMaterial().SetTexture("_MainTex",source);		
		
		RenderBuffer[] buffers = new RenderBuffer[2];
		buffers[0] = meanCol.colorBuffer;
		buffers[1] = meanPos.colorBuffer;
		
		Graphics.SetRenderTarget(buffers,meanCol.depthBuffer);		
		Graphics.Blit(source,meanCol,MeanShiftMaterial(),0);
}

Doesn’t work.

I tried it with Graphics.DrawTexture, nothing.

Any help hugely appreciated!

2

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:

using UnityEngine;
using System.Collections;

[ExecuteInEditMode]
[RequireComponent(typeof(Camera))]

public class TestMRT : PostEffectsBase
{
	private Material testMRTMaterial = null;
	private RenderTexture[] mrtTex = new RenderTexture[2];
	private RenderBuffer[] mrtRB = new RenderBuffer[2];

	void Start ()
	{
		mrtTex[0] = new RenderTexture(Screen.width, Screen.height, 24, RenderTextureFormat.ARGB32);
		mrtTex[1] = new RenderTexture(Screen.width, Screen.height, 24, RenderTextureFormat.ARGB32);
		mrtRB[0] = mrtTex[0].colorBuffer;
		mrtRB[1] = mrtTex[1].colorBuffer;
	}

	public override bool CheckResources()
	{
		CheckSupport(true);

		testMRTMaterial = CheckShaderAndCreateMaterial(Shader.Find("Custom/TestMRT"), testMRTMaterial);

		if (!isSupported)
			ReportAutoDisable();
		return isSupported;
	}

	void OnRenderImage(RenderTexture source, RenderTexture destination)
	{
		if (CheckResources() == false)
		{
			Graphics.Blit(source, destination);
			return;
		}

		RenderTexture oldRT = RenderTexture.active;

		Graphics.SetRenderTarget(mrtRB, mrtTex[0].depthBuffer);

		GL.Clear(false, true, Color.clear);

		GL.PushMatrix();
		GL.LoadOrtho();

		testMRTMaterial.SetPass(0);		//Pass 0 outputs 2 render textures.

		//Render the full screen quad manually.
		GL.Begin(GL.QUADS);
		GL.TexCoord2(0.0f, 0.0f); GL.Vertex3(0.0f, 0.0f, 0.1f);
		GL.TexCoord2(1.0f, 0.0f); GL.Vertex3(1.0f, 0.0f, 0.1f);
		GL.TexCoord2(1.0f, 1.0f); GL.Vertex3(1.0f, 1.0f, 0.1f);
		GL.TexCoord2(0.0f, 1.0f); GL.Vertex3(0.0f, 1.0f, 0.1f);
		GL.End();

		GL.PopMatrix();

		RenderTexture.active = oldRT;

		//Show the result
		testMRTMaterial.SetTexture("_Tex0", mrtTex[0]);
		testMRTMaterial.SetTexture("_Tex1", mrtTex[1]);
		Graphics.Blit(source, destination, testMRTMaterial, 1);
	}
}

And the shader code:

Shader "Custom/TestMRT" {
	Properties {
		_MainTex ("", 2D) = "" {}
	}
	
	CGINCLUDE
	
	#include "UnityCG.cginc"
	 
	struct v2f {
		float4 pos : POSITION;
		float2 uv : TEXCOORD0;
	};
	
	struct PixelOutput {
		float4 col0 : COLOR0;
		float4 col1 : COLOR1;
	};
	
	sampler2D _MainTex;
	sampler2D _Tex0;
	sampler2D _Tex1;
	
	v2f vert( appdata_img v ) 
	{
		v2f o;
		o.pos = mul(UNITY_MATRIX_MVP, v.vertex);
		o.uv = v.texcoord.xy;
		return o;
	}
	
	PixelOutput fragTestMRT(v2f pixelData)
	{
		PixelOutput o;
		o.col0 = float4(1.0f, 0.0f, 0.0f, 1.0f);
		o.col1 = float4(0.0f, 1.0f, 0.0f, 1.0f);
		return o;
	}
	
	float4 fragShowMRT(v2f pixelData) : COLOR0
	{
		return tex2D(_Tex0, pixelData.uv);
		//return tex2D(_Tex1, pixelData.uv);
	}
	
	ENDCG 
	
Subshader {
 Pass {
	  ZTest Always Cull Off ZWrite Off
	  Fog { Mode off }

      CGPROGRAM
	  #pragma glsl
      #pragma fragmentoption ARB_precision_hint_fastest 
      #pragma vertex vert
      #pragma fragment fragTestMRT
	  #pragma target 3.0
      ENDCG
  }
 Pass {
	  ZTest Always Cull Off ZWrite Off
	  Fog { Mode off }

      CGPROGRAM
	  #pragma glsl
      #pragma fragmentoption ARB_precision_hint_fastest 
      #pragma vertex vert
      #pragma fragment fragShowMRT
	  #pragma target 3.0
      ENDCG
  }
}

Fallback off
	
}
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