Smooth Overlap with Semi-Transparent Geometry

I'm having difficulty with drawing overlapping semi-transparent cubes. Basically, I'd like to have two semi-transparent blue cubes which overlap seamlessly. If I use the built-in Alpha-Diffuse shader, then there is a dark spot where the cubes overlap (see attached picture).

Most of the solutions to this that I've seen say to enable ZWrite on the shader, but that doesn't work in this case for some reason. Below is a copy of my attempt at enabling ZWrite, it didn't get rid of the dark overlapping area. I'm not very famiilar with shaders, so any help would be appreciated.

Code (csharp):

1.  
2. Shader "Transparent/DiffuseZWriteOff" {
3. Properties {
4.     _Color ("Main Color", Color) = (1,1,1,1)
5.     _MainTex ("Base (RGB) Trans (A)", 2D) = "white" {}
6. }
7.  
8. SubShader {
9.     Tags {"Queue"="Transparent" "IgnoreProjector"="True" "RenderType"="Transparent"}
10.     LOD 200
11.  
12.     Pass
13.     {
14.         ZWrite On
15.         ColorMask 0
16.     }
17.  
18. CGPROGRAM
19. #pragma surface surf Lambert alpha
20.  
21. sampler2D _MainTex;
22. fixed4 _Color;
23.  
24. struct Input {
25.     float2 uv_MainTex;
26. };
27.  
28. void surf (Input IN, inout SurfaceOutput o) {
29.     fixed4 c = tex2D(_MainTex, IN.uv_MainTex) * _Color;
30.     o.Albedo = c.rgb;
31.     o.Alpha = c.a;
32. }
33. ENDCG
34. }
35.  
36. Fallback "Transparent/Diffuse"
37. }
38.  
39.  

 

Hi,

I had the same problem, and I found this shader code which solves it:
http://answers.unity3d.com/questions/290333/transparent-solid-color-shader.html

Cheers,
Nicolas

 

Thanks for the link, I tried that shader and I believe it doesn't work if the overlapping happens between different meshes. My guess is that what I'm trying to do is actually impossible, because the rendering pipeline doesn't allow it. Unfortunately, I know enough about that pipeline to verify that.

 

Hi,

did you try the stencil buffer?
Usually you can use the stencil buffer for this.
Here is a example for sprites but this should work for meshes too: http://wompipomp.blogspot.de/2015/10/use-stencil-buffer-to-prevent.html

Put this before CGPROGRAM
Stencil
{
Ref 1
Comp Greater
Pass IncrSat
}

both meshes must use the shader with the stencil buffer.

Cheers
Mark

 

The Stencil worked perfectly, thanks

Final Shader is

Code (csharp):

1.  
2. Shader "Test/Alpha-Diffuse-Test" {
3. Properties {
4.     _Color ("Main Color", Color) = (1,1,1,1)
5.     _MainTex ("Base (RGB) Trans (A)", 2D) = "white" {}
6. }
7.  
8. SubShader {
9.     Tags {"Queue"="Transparent" "IgnoreProjector"="True" "RenderType"="Transparent"}
10.     LOD 200
11.  
12.     Stencil
13. {
14. Ref 1
15. Comp Greater
16. Pass IncrSat
17. }
18.  
19. CGPROGRAM
20. #pragma surface surf Lambert alpha
21.  
22. sampler2D _MainTex;
23. fixed4 _Color;
24.  
25. struct Input {
26.     float2 uv_MainTex;
27. };
28.  
29. void surf (Input IN, inout SurfaceOutput o) {
30.     fixed4 c = tex2D(_MainTex, IN.uv_MainTex) * _Color;
31.     o.Albedo = c.rgb;
32.     o.Alpha = c.a;
33. }
34. ENDCG
35. }
36.  
37. Fallback "Transparent/VertexLit"
38. }
39.  
40.