Resolved Custom depth map with custom matrices.

I've been fighting with this for a while now and I have no ideas anymore.

I want to create a depth map/texture with my shader. I don't use the macros/functions from unity because they are based on the camera's matrices (I guess). I use my matrices. I get the scene drawn to a texture completely fine, but I can't create a depth texture from it.

I tried multiple ways to achieve this. Here some code to get a better understanding of my problem. this will be called every update:

Code (CSharp):

1.  // Remember the current texture and set our own as "active".
2. RenderTexture prevRT = RenderTexture.active;
3. RenderTexture.active = renderTexture;
4.  
5. // Set material as "active". Without this, Unity editor will freeze.
6. material.SetPass(0);
7.  
8. // Push the projection matrix
9. GL.PushMatrix();
10.  
11. // `projectionMatrix` is an ortho projection
12. GL.LoadProjectionMatrix(projectionMatrix);
13.  
14. // `viewMatrix` is a TRS matrix
15. material.SetMatrix("_viewMatrix", viewMatrix);
16.  
17. // Clear the texture
18. GL.Clear(true, true, Color.white);
19.  
20.  
21. // bunch of meshes
22. foreach (var mesh in meshes){
23.     Quaternion rotation = Quaternion.Euler(mesh.rotation);
24.     // Create the model matrix
25.     Matrix4x4 objectMatrix = Matrix4x4.TRS(mesh.position, rotation, mesh.scale);
26.  
27.     // Draw the mesh!
28.     Graphics.DrawMeshNow(mesh.mesh, objectMatrix);
29. }
30.  
31. // Pop the projection matrix to set it back to the previous one
32. GL.PopMatrix();
33.  
34. // Re-set the RenderTexture to the last used one
35. RenderTexture.active = prevRT;

So this draws everything fine into a RenderTexture which has a shader attached. The shader is an unlit shader which is very basic.

Code (CSharp):

1. //...
2. SubShader
3. {
4.     Pass
5.     {
6.         CGPROGRAM
7.         #pragma vertex vert
8.         #pragma fragment frag
9.  
10.         #include "UnityCG.cginc"
11.  
12.         float4x4 _viewMatrix;
13.  
14.         struct appdata
15.         {
16.             float4 vertex : POSITION;
17.         };
18.  
19.         struct v2f
20.         {
21.             float4 vertex : SV_POSITION;
22.             float2 depth : DEPTH;
23.         };
24.  
25.         v2f vert (appdata v)
26.         {
27.             v2f o;
28.             float4 vertex = v.vertex;
29.             float4x4 mv = mul(_viewMatrix, unity_ObjectToWorld);
30.             float4x4 mvp = mul(UNITY_MATRIX_P, mv);
31.             vertex = mul(mvp, vertex);
32.             o.vertex = vertex;
33.             o.depth = vertex.zw;
34.             return o;
35.         }
36.  
37.         fixed4 frag (v2f i) : SV_Target
38.         {
39.             half depth = i.depth.x / i.depth.y;
40.             return fixed4(depth,depth,depth,1);
41.         }
42.         ENDCG
43.     }
44. }
45. //...

I also tried to just return 0 in the pixel shader by disabling Cull Off and ZWrite On. The result that I get is always a black or transparent texture where the meshes are. So, there is no depth.

Has someone an idea how I can create a depth map with custom matrices? I'd appreciate any help.

 

In the meanwhile, I got help somewhere else and I wanted to post the solution in case someone else might have the same problem. See comments for the changes.

Code (CSharp):

1. struct v2f
2. {
3.     float4 vertex : SV_POSITION;
4.     // this line below is new
5.     float depth : DEPTH;
6. };
7.  
8. v2f vert (appdata v)
9. {
10.     v2f o;
11.     float4 vertex = v.vertex;
12.     float4x4 mv = mul(_viewMatrix, unity_ObjectToWorld);
13.     float4x4 mvp = mul(UNITY_MATRIX_P, mv);
14.     vertex = mul(mvp, vertex);
15.     o.vertex = vertex;
16.     // this line below is new
17.     o.depth = -mul(mv, v.vertex).z * _ProjectionParams.w;
18.     return o;
19. }
20.  
21. fixed4 frag (v2f i) : SV_Target
22. {
23.     // this line below is new
24.     half depth = i.depth;
25.     return fixed4(depth,depth,depth,1);
26. }