graphics.blit ( src, dest, mat) How to grab the src in the shader?

Hi everyone,

I use the graphics.blit ( src, dest, mat) in a cs script.
Unfortunately I did not receive the src in the frag() shader.

I tried to grab the src from the _MainTex after using graphics.blit graphics.blit ( src, dest, mat)
but it stays white.

Code (CSharp):

1.  
2.        dest = new RenderTexture(256, 256, 0);
3.        ...
4.        src = new RenderTexture(256, 256, 0);
5.        src.wrapMode = TextureWrapMode.Repeat;
6.  
7.        // init color for RT                    
8.       RenderTexture.active = src;
9.       GL.Begin(GL.TRIANGLES);
10.       GL.Clear(true, true, new Color(.2f, .3f, .6f, 1));
11.       GL.End();
12.  
13.       Graphics.Blit(src, dest, mat);
14.  
15.  

Test frag() shader:

Code (CSharp):

1. Properties
2.     {
3.         _MainTex    ("Base (RGB)", 2D) = "white" { }
4.     }
5.  
6.     SubShader {
7.  
8.     Lighting Off
9.     ZTest Always Cull Off ZWrite Off
10.         Fog { Mode off }
11.  
12.         Pass {
13.         CGPROGRAM
14.             #pragma target 3.0
15.             #pragma vertex vert
16.             #pragma fragment frag
17.             #include "UnityCG.cginc"
18.          
19.             uniform sampler2D _MainTex;
20.                                  
21.             // TRANSFORM_TEX in the vertex method
22.             // _ST variables are automatically populated with the
23.             // texture tiling (x,y) and Offset (z,w) values from the
24.             // correspondingly-named texture (in this case, _MainTex).                                      
25.  
26.          half4 _MainTex_ST;                                              
27.                                  
28.             struct v2f {
29.                 float4 pos    : SV_POSITION;
30.                 float2 mainuv : TEXCOORD0;
31.             };
32.          
33.         v2f vert (appdata_base v){
34.         v2f o;
35.         o.pos         = mul (UNITY_MATRIX_MVP, v.vertex);
36.         o.mainuv     = TRANSFORM_TEX (v.texcoord.xy, _MainTex);
37.         // Tried both..  
38.         //o.mainuv     = v.texcoord;
39.         return o;
40.                }
41.          
42.             half4 frag (v2f i) : COLOR0{
43.          
44.                 half3  main = tex2D(_MainTex, i.mainuv).xyz;
45.                  return half4(main.x , main.y, main.z, 1);  
46.             }
47.  
48.             ENDCG
49.         }
50.     }

How to receive the src coming from the graphics.blit ( src, dest, mat) then?

Thanks and kind regards,
Quatum

 

Try this:

Code (CSharp):

1. Shader "YourShader" {
2.     Properties {
3.         _MainTex ("Base (RGB)", 2D) = "" {}
4.     }
5.     SubShader {
6.         ZTest Always Cull Off ZWrite Off Fog { Mode Off }
7.         Pass {
8.             CGPROGRAM
9.             #pragma vertex vert_img
10.             #pragma fragment frag
11.             #pragma fragmentoption ARB_precision_hint_fastest
12.             #include "UnityCG.cginc"
13.            
14.             uniform sampler2D _MainTex;
15.  
16.             fixed4 frag(v2f_img i) : COLOR {
17.            
18.                 fixed4 renderTex = tex2D( _MainTex, i.uv);
19.                 return renderTex;
20.             }
21.            
22.             ENDCG
23.         }
24.        
25.     }
26.  
27. }
28.  

The code is tested and it works. But if it does not, then you are probably doing something wrong while blitting.

 

Graphics.Blit is mostly used for implementing image effects, and requires Unity Pro. Unity Free does not support anything that involves RenderTexture.

 

Thanks for your answers.. Yes I have the pro version U5RC2.

 

Unfortunately it does not currently. Here is an full example:
Don't know whats wrong here.

I want to change the SRC texture in the Shader and the result should to into DST.
Does anyone know how to do correctly?
Thank you..

Code (CSharp):

1. Shader "Custom/RT2Shader" {
2. Properties {
3.         _MainTex ("Base (RGB)", 2D) = "" {}
4.     }
5.     SubShader {
6.         ZTest Always Cull Off ZWrite Off Fog { Mode Off }
7.         Pass {
8.             CGPROGRAM
9.             #pragma vertex vert_img
10.             #pragma fragment frag
11.             #pragma fragmentoption ARB_precision_hint_fastest
12.             #include "UnityCG.cginc"
13.      
14.             uniform sampler2D _MainTex;
15.             fixed4 frag(v2f_img i) : COLOR {
16.      
17.                 fixed4 renderTex = tex2D( _MainTex, i.uv);
18.                 return renderTex;
19.             }
20.      
21.             ENDCG
22.         }
23.     }
24. }
25.  

C#

Code (CSharp):

1. using UnityEngine;
2. using System.Collections;
3.  
4. public class RT2Shader : MonoBehaviour {
5.  
6.     public RenderTexture Src;
7.     public RenderTexture Dst;
8.     public Material Mat;
9.  
10.     void Start () {
11.  
12.         Src = new RenderTexture(256, 256, 0);
13.         Dst = new RenderTexture(256, 256, 0);
14.     }
15.  
16.     void Update () {
17.  
18.         // Green in
19.         RenderTexture.active = Src;
20.         GL.Begin(GL.TRIANGLES);
21.         GL.Clear(true, true, new Color(0f, 1f, 0f, 1f));
22.         GL.End();
23.  
24.         RenderTexture.active = Dst;
25.         GL.Begin(GL.TRIANGLES);
26.         GL.Clear(true, true, new Color(1f, 0f, 0f, 1f));
27.         GL.End();
28.  
29.         Graphics.Blit(Src, Dst, Mat);
30.         // Red was overwritten with Green
31.     }
32. }
33.  

Src (Green) will transfered directly into DST.