Render Target in Grabpass and Forward Shader ? (deferred)

Hi everyone,

I have created a forward transparent water shader in deferred mode. The shader use a grabpass to build refraction and and cost foam line. The structure of the shader is like this:

Code (CSharp):

1. SubShader{
2.     Tags{ "Queue" = "Transparent" }
3.     LOD 300
4.     Cull [_Culling]
5.     Zwrite Off
6.     GrabPass{ "_GrabTexture" }
7.     #pragma surface surf StandardSpecularWater nolightmap keepalpha nofog
8.     #pragma target 4.0
9.     #include "Includes/WaterPBSLighting.cginc"
10.  
11.     sampler2D _GrabTexture;
12.     sampler2D _CameraDepthTexture;
13.  
14.     struct Input {
15.         float2 uv_NormalMap; // master uvs
16.         float3 viewDir;
17.         float3 worldPos;
18.         float4 screenPos;
19.         float3 worldNormal;
20.         INTERNAL_DATA
21.     };
22.  
23.     void surf(Input IN, inout SurfaceOutputStandardSpecularWater o) {
24.            edge_blend_area = xxxxxxxx;
25.            // Write out Edge blend data into a RT?
26.     }
27. }
28.  

All the stuff works fine until here.

The edge_blend_area depth is already calculated correctly, where the water plane intersect any other mesh.


Now I'd like to write out the edge_blend_area as gray scale depth data into a render-target inside the surf pass. Or is there any possibility to write the info out into a render-target?

At least I want to have a render target it based on the edge blend mask. I'd like to prevent to render all the stuff twice as a proxy.

Further I read many stuff about MRTs and the special decal thread. But all this doesn't help me really. Any ideas?

Thank you.