Problems Trying To Write To RWTextures From Frag Shaders..

No matter what I do, I cannot seem to write to an RWTexture from a frag shader. Simply nothing happens, and there is absolutely no documentation on this. I've looked through the forums and lots of others seem to have similar problems, but I never see any real solutions.


In this shader I attempt to write red into 0,0 of the RWTexture, but the value always comes out black.

Code (CSharp):

1. Shader "Custom/RenderToVolume"
2. {
3.      Properties
4.      {
5.          _MainTex ("Diffuse (RGBA)", 2D) = "white" {}
6.      }
7.      SubShader
8.      {
9.          Pass
10.          {
11.              Tags { "RenderType"="Opaque" }
12.              Cull Off ZWrite Off ZTest Always Fog { Mode Off }
13.              CGPROGRAM
14.              #pragma target 5.0
15.              #pragma vertex vert
16.              #pragma fragment frag
17.              #pragma exclude_renderers flash gles opengl
18.              #include "UnityCG.cginc"
19.              sampler2D _MainTex;
20.              RWTexture2D<float4> volTex;
21.              float volumeResolution;
22.              float4 volumeParams;
23.  
24.  
25.  
26.  
27.              struct ApplicationToVertex
28.              {
29.                  float4 vertex : POSITION;
30.                  float4 texcoord : TEXCOORD0;
31.              };
32.              struct VertexToFragment
33.              {
34.                  float4 pos : SV_POSITION;
35.                  float4 wPos : TEXCOORD0;
36.                  float2 uv : TEXCOORD1;
37.              };
38.              void vert(ApplicationToVertex input, out VertexToFragment output)
39.              {
40.                  output.pos = UnityObjectToClipPos (input.vertex);
41.                  output.wPos = mul(unity_ObjectToWorld, input.vertex);
42.                  output.uv = input.texcoord.xy;
43.              }
44.  
45.  
46.  
47.  
48.  
49.  
50.              void frag(VertexToFragment input)
51.              {
52.                  float4 color = tex2D(_MainTex, input.uv);
53.                
54.            
55.                  volTex[float2(0,0)] = float4(1,0,0,1);
56.                
57.              }
58.              ENDCG
59.          }
60.      }
61.      Fallback Off
62. }

Here is the C# part.

Code (CSharp):

1.     void OnPostRender(){
2.         Graphics.ClearRandomWriteTargets ();
3.  
4.  
5.  
6.         Graphics.SetRandomWriteTarget(1, RText);
7.         cam.SetReplacementShader(RShader, "RenderType");
8.  
9.  
10.         Shader.SetGlobalTexture ("volTex",RText);
11.  
12.         cam.SetReplacementShader(RShader, "RenderType");
13.         ComputeVol.SetTexture (1,"VolumeIn",RText);
14.         ComputeVol.SetTexture (0,"VolumeIn",RText);
15.  
16.         Graphics.ClearRandomWriteTargets ();
17.  
18.  
19.     }

Here's where the render texture(RText) is intialized

Code (CSharp):

1.     RenderTexture NewText(int Res)
2.     {
3.         RenderTexture Diftex = new RenderTexture(Res, Res, 16, RenderTextureFormat.ARGBFloat);
4.  
5.         Diftex.hideFlags = HideFlags.HideAndDontSave;
6.         Diftex.filterMode = FilterMode.Point;
7.  
8.         Diftex.enableRandomWrite = true;
9.         Diftex.useMipMap = false;
10.  
11.         Diftex.Create();
12.         Graphics.SetRenderTarget(Diftex);
13.         GL.Clear(false, true, new Color(0,0,0,0));
14.         return Diftex;
15.     }

 

Bump. Anyone solved this problem?

 

Bump: Also having a similar issue. Can't get a RWTexture2D written to in a pixel shader. I've defined mine like this based on another thread:

uniform RWTexture2D<float4> _RWTexture : register(u1);

supposedly specifying the register is key.

 

Holy jeez I finally found out the issue. You MUST specify the RenderTarget AFTER you've specified SetRandomWriteTarget (see https://forum.unity3d.com/threads/h...ss-compute-buffer-from-a-pixel-shader.403783/).