GrabPass - solid color instead of skybox

Hey there.

So, I am using GrabPass to achieve some nice looking, but still cheap effects. The thing is, there's no skybox grabbed, only the camera's clear color.

Like this:



I've seen that when other people use Grabpass, they don't seem to have this problem.

Here's the shader I use (I use deferred rendering, btw):

Code (CSharp):

1. Shader "Custom/Effects/WindSlash"
2. {
3.     Properties
4.     {
5.         _NoiseTex("Bump (RGB)", 2D) = "bump" {}
6.         _Alpha("Alpha", Float) = 1.0
7.     }
8.     SubShader
9.     {
10.         Tags{ "RenderType" = "Transparent" "Queue" = "Transparent" }
11.        
12.         GrabPass{ "_GrabTexture" }
13.         Pass
14.         {
15.             CGPROGRAM
16.             #pragma target 3.0
17.             #pragma vertex vert
18.             #pragma fragment frag
19.             // make fog work
20.             #pragma multi_compile_fog
21.            
22.             #include "UnityCG.cginc"
23.  
24.             struct appdata
25.             {
26.                 float4 vertex : POSITION;
27.             };
28.  
29.             struct v2f
30.             {
31.                 float4 vertex : SV_POSITION;
32.                 float4 scrPos : COLOR;
33.             };
34.  
35.             sampler2D _GrabTexture;
36.             float _Alpha;
37.  
38.             sampler2D _NoiseTex;
39.            
40.             v2f vert (appdata_base v)
41.             {
42.                 v2f o;
43.                 o.vertex = mul(UNITY_MATRIX_MVP, v.vertex);
44.  
45.                 o.scrPos = ComputeScreenPos(o.vertex);
46.                 return o;
47.             }
48.            
49.             fixed4 frag (v2f i) : SV_Target
50.             {
51.                 i.scrPos.xy /= i.scrPos.w;
52.  
53.                 fixed2 noise = UnpackNormal(tex2D(_NoiseTex, i.scrPos.xy + _Time * 0.3f)).xy;
54.                 float w = (abs(noise.y) * 0.15f + 1.0f);
55.                 fixed4 col = tex2D(_GrabTexture, i.scrPos.xy + noise.xy * 0.02f) * float4(1.0 * w, 1.0 * w, 1.6 * w, 1.0);
56.                 fixed4 realCol = tex2D(_GrabTexture, i.scrPos.xy);
57.                 return lerp(realCol, col, _Alpha);
58.             }
59.             ENDCG
60.         }
61.     }
62. }
63.  

Is this the expected behavior? Any way to fix it, or will I have to go back to rendering the whole scene two times to draw it to a render texture first?

 

Grabpass should work.
Maybe check if your main camera's clear flags setting to "Skybox" ?