Water Volume Shader

Hello everyone,

I want to render water volumes, like cubes of water with a depth gradient effect. I started with a shader from catlike coding, that reads the _CameraDepthTexture, provided by Unity and applies some fog, according to the depth of the previously rendered scene. Additionaly the shader uses a GrabPass to add refraction effects.



This works well so far. You'll find the source here: https://catlikecoding.com/unity/tutorials/flow/looking-through-water/

Adding this excact shader to a water cube creates problems however. The Background is very far away and this makes the depth fog very strong. The cube is opaque although it is not a very thick water volume.



This shader runs in the transparent quene, including the GrabPass. I wrote a second shader on a second material, rendering on the geometry quene. This shader culls the front (outside) and renders only the inside cube.

I am currently using a ShadowCaster pass to write the depth texture before the depth fog reads it. I works well, however it interferes with the shadows in a weired way. this is why I don't want to use the ShadowCaster pass.



Below my backside shader. It should only write to depth. I don't want shadows at all.

Code (CSharp):

1. Shader "Custom/ack"
2. {
3.     Properties
4.     {
5.         _Color("Color", Color) = (1,1,1,1)
6.         _MainTex("Albedo (RGB)", 2D) = "white" {}
7.         _Glossiness("Smoothness", Range(0,1)) = 0.5
8.         _Metallic("Metallic", Range(0,1)) = 0.0
9.     }
10.         SubShader
11.         {
12.             //back side pass
13.                     Tags { "RenderType" = "Opaque" "Queue" = "Geometry"}
14.                     LOD 200
15.  
16.             Cull Front
17.             ZWrite On
18.             Blend SrcAlpha OneMinusSrcAlpha
19.  
20.             Pass
21.         {
22.             Tags {"LightMode" = "ShadowCaster"}
23.  
24.             CGPROGRAM
25.             #pragma vertex vert
26.             #pragma fragment frag
27.             #pragma multi_compile_shadowcaster
28.             #include "UnityCG.cginc"
29.  
30.             struct v2f {
31.                 V2F_SHADOW_CASTER;
32.             };
33.  
34.             v2f vert(appdata_base v)
35.             {
36.                 v2f o;
37.                 TRANSFER_SHADOW_CASTER_NORMALOFFSET(o)
38.                 return o;
39.             }
40.  
41.             float4 frag(v2f i) : SV_Target
42.             {
43.                     SHADOW_CASTER_FRAGMENT(i)
44.             }
45.             ENDCG
46.         }
47. }
48. }

 

Seeing as you're rendering a box, you can do a ray-box intersection to find the endpoint of the ray, and use that as your water distance, if it is closer than the background (Depth), its easier than messing around with depth for this particular case.

 

I don't quite understand how I can get this running in a shader. Additionally, the box is just a test. Eventually the shape will be arbitrary.