It would be too much to say that I wrote this shader, but I did just assemble it from pieces of other shaders. Anyway…

Here’s an additive shader that takes a color and a texture.

Shader "Additive Texture with Color" {
 
Properties {
    _Color ("Main Color", Color) = (1,1,1,1)
    _MainTex ("Texture", 2D) = ""
}
 
SubShader {
    Tags {Queue = Transparent}
    Blend One One
    ZWrite Off
    Pass {
        SetTexture[_MainTex] {
        	constantColor [_Color]
            Combine texture * constant
        }
    } 
}
 
}