Convert images to black-and-white format with alpha channel

Unity Engine
1

Hello, my shader is not working properly with an alpha channel, what went wrong?

Shader "Custom/BWDiffuse" {
    Properties{
        _MainTex("Base (RGB)", 2D) = "white" {}
        _bwBlend("Blend", Range(0, 1)) = 0
    }
        SubShader{
        Pass{ Blend SrcAlpha OneMinusSrcAlpha
        CGPROGRAM
#pragma vertex vert_img
#pragma fragment frag

#include "UnityCG.cginc"

        uniform sampler2D _MainTex;
    uniform float _bwBlend;

    float4 frag(v2f_img i) : COLOR{
        float4 c = tex2D(_MainTex, i.uv);

        float lum = c.r*.3 + c.g*.59 + c.b*.11;
        float3 bw = float3(lum, lum, lum);

        float4 result = c;
        result.rgb = lerp(c.rgb, bw, 1 - _bwBlend);
        return result;
    }
        ENDCG
    }
    }
}
2

why not just use float3 bw =Luminance(c.rgb);?

3

This don’t significantly, the result does not change.

4

adding test scene, showing the bug.

2340293–158243–test.unitypackage (1.4 MB)

2340293--158245--test.png
2340293--158245--test.png772Ă—1007 142 KB

5

You need to tell the shader not to write to the depth buffer by using ZWrite Off. You should also set some tags, like “Queue”=“Transparent”, “RenderType”=“Transparent”, and “IgnoreProjector”=“True”. Check it out here: Unity - Manual: ShaderLab: assigning tags to a SubShader

Here’s your shader back. This works in your test scene.

2341061–158309–test.shader (699 Bytes)

1 Like
6

Thank you