Unity Diffuse Shader with Global Alpha

Question

I'm trying to make a simple diffuse shader in Unity, though with a global alpha value. So you add a texture (without alpha), and then define an alpha value in the shader (float between 0 and 1.) The entire texture then is transparent.

This is what I already have, it's just the most basic diffuse shader you can image, though I'm stuck at adding the alpha.

Properties
{
    _Alpha ("Alpha", Range (0.0,1.0)) = 0.0 
    _MainTex ("Base (RGB) Transparency (A)", 2D) = "" { }
}

SubShader
{
    Pass
    {
        SetTexture [_MainTex] { combine texture }
    }
}

Thanks,

user673679 · Accepted Answer · 2012-11-16 13:51:53Z

1

It's been a while since I've done any of this, but I think you want something like:

SubShader
{
    Tags { "Queue" = "Transparent" }

    Pass
    {
        Blend SrcAlpha OneMinusSrcAlpha

        SetTexture [_MainTex] {
           constantColor (1, 1, 1, [_Alpha])
           combine texture * constant
        }
    }
}

Note that you can download the built-in shaders for unity from here, they're pretty useful to learn from.

answered Nov 16, 2012 at 13:51

user673679

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3 Comments

The Oddler Over a year ago

this almost works! it has to be "constantColor (1, 1, 1, [_Alpha])" otherwise the texture is black. Thanks!

The Oddler Over a year ago

Awesomeness, I'm starting to understand this shaderlab stuff, one of the hardest things in Unity I think :P

user652038 Over a year ago

That isn't semantically the best; I'd either multiply the entire color, or just do a calculation for A and leave RGB alone: Combine texture, texture * constant

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