Surf Depth Shader

Unity Engine
1

I’m using frag shader for show depth texture and it works. When I,m trying do the same in the surface shader I’m seeing black screen. Why?))

    void OnRenderImage(RenderTexture src, RenderTexture dest)
    {
        Material mat = Resources.Load("materials/TestBuffer", typeof(Material)) as Material;
        Graphics.Blit(src, dest, mat);
    }

working shader

Shader "Custom/ZBufTest" {
    SubShader{
        Tags{ "RenderType" = "Opaque" }

        Pass{
        CGPROGRAM
            #pragma vertex vert
            #pragma fragment frag
            #include "UnityCG.cginc"

            sampler2D _CameraDepthTexture;

            struct v2f {
                float4 pos : SV_POSITION;
                float4 scrPos:TEXCOORD1;
            };

            v2f vert(appdata_base v) {
                v2f o;
                o.pos = mul(UNITY_MATRIX_MVP, v.vertex);
                o.scrPos = ComputeScreenPos(o.pos);

                return o;
            }

            half4 frag(v2f i) : COLOR
            {
                float depthValue = Linear01Depth(tex2Dproj(_CameraDepthTexture, UNITY_PROJ_COORD(i.scrPos)).r);
             
                depth.r = depthValue;
                depth.g = depthValue;
                depth.b = depthValue;

                depth.a = 1;
                return depth;
            }
        ENDCG
        }
    }
    FallBack "Diffuse"
}

notworking shader

Shader "Custom/ZBufTest"
{
    Properties
    {

    }
    SubShader
    {
        CGPROGRAM

        #include "UnityCG.cginc"
        #pragma surface surf Lambert vertex:vert alpha addshadow

        #pragma target 3.0

        sampler2D _CameraDepthTexture;

        struct Input
        {
            float2 uv_MainTex;
            float4 screenPos;

            float eyeDepth;
        };


        void vert(inout appdata_full v, out Input o)
        {
            UNITY_INITIALIZE_OUTPUT(Input, o);

            float4 vpos = mul(UNITY_MATRIX_MVP, v.vertex);
            o.screenPos = ComputeScreenPos(vpos);
        }

        void surf (Input IN, inout SurfaceOutput o)
        {
    
            float depthValue = Linear01Depth(tex2Dproj(_CameraDepthTexture, UNITY_PROJ_COORD(IN.screenPos)).r);

            half4 depth;
          
            depth.r = depthValue;
            depth.g = depthValue;
            depth.b = depthValue;
          
            depth.a = 1;
          

            o.Albedo = depth;

        }
        ENDCG
    }
    FallBack "Diffuse"
}
2

Surface shaders don’t work properly with blit, and they shouldn’t be expected to. You’re setting the Albedo (the surface color) to the depth, but a material rendered using blit will receive no lighting information and always render as black (albedo * no lighting). You can try doing o.Emission = depth instead, but the shader is still doing all of the work to calculate lighting it doesn’t have!

3

I’ve tried to use even o.Albedo = float3(1, 1, 1) and o.Emission = float3(1, 1, 1), but screen is still black))
Actually I need to use depth buffer for adjusting water opacity near coastline. Maybe instead blit I need to use other approach?

4

Ok. I transfer this surf shader to water material, so it works and I’m getting landscape mesh depth from buffer. If I need to clip water pixels along coastline, how i can compare it with water z value (water use ZWrite off)? Also, how can I add some random for clipping