Make object transparent using compositing?

Unity Engine
1

I want to achieve something like this:

Rather than this:

In the first image, the soldier is actually fully opaque, but the result alpha of the whole soldier render is multiplied by a factor. In the second one, the object is using the standard alpha channel for transparency with Z sorting, which causes it to be more or less transparent in some places due to faces overlapping. I don’t want that.

Is this possible to do with a shader?

I suppose it would be possible using multiple cameras and render textures, but that seems a bit long-winded. Also I’m trying to accomplish this in Unity Free, which does not support render textures.

Any ideas?

Thanks.

2

Searching text isn’t effective to get an answer for this type of thing, I think. I looked at the Google image results for “unity render transparent object”, and clicked on an illustration of the problem. I bet there’s a similar search term that would have been more “you” before I influenced your thinking.

1 Like
3

Thanks @Jessy .

Shader "Transparent/Diffuse ZWrite" {
Properties {
    _Color ("Main Color", Color) = (1,1,1,1)
    _MainTex ("Base (RGB) Trans (A)", 2D) = "white" {}
}
SubShader {
    Tags {"Queue"="Transparent" "IgnoreProjector"="True" "RenderType"="Transparent"}
    LOD 200

    // extra pass that renders to depth buffer only
    Pass {
        ZWrite On
        ColorMask 0
    }

    // paste in forward rendering passes from Transparent/Diffuse
    UsePass "Transparent/Diffuse/FORWARD"
}
Fallback "Transparent/VertexLit"
}

Where that extra Zwrite pass at line 11 is the actual solution.

I wonder if there’s a way to set a thing like this up in Shader Forge. From what I gathered, Shader Forge does not allow setting up manual passes. That’s a shame. I suppose I could design the shader like I want in shader forge and hack the last bit (edit: just tried it and works fine).

2 Likes
4

Glad you found it. I was about to roll-eyes, sigh and link the documentation :wink:
Everyone will find 9 out of 10 solutions are solved with a bit of google magic!

1 Like
5

Haha, thanks. Not sure what I googled. While finding plenty of texts stating self-intersecting geometry is a real pain for transparent objects and one needs to sort triangles in code and so on, I didn’t find this simple solution. Exactly what I was looking for.

6

I guess part of google fu is searching for the term you should be searching for.