How can i add a alpha value to this shader?

Questions & Answers
1

I need the _MainTextue to have a alpha setting.

Shader "ALTO/Additive Overlay Alpha" {
	Properties{
	_MainTex("Texture 1", 2D) = "white" {}
	_SecondaryTex("Texture 2", 2D) = "white" {}
	_SecondaryTexScale("Texture 2 Scale", Color) = (0,0,0,0)
	}

		Category{

		Tags{ "Queue" = "Overlay" }

		Blend SrcAlpha One
		Cull Back Lighting Off ZWrite Off Fog{ Mode Off }
		ZTest Always

		BindChannels{
		Bind "Color", color
		Bind "Vertex", vertex
		Bind "TexCoord", texcoord
	}

		SubShader{
		Tags{ "LightMode" = "Vertex" }
		Pass{
		SetTexture[_SecondaryTex]{
		constantColor[_SecondaryTexScale]
		combine texture * constant
	}
		SetTexture[_MainTex]{
		combine texture + previous
	}
		SetTexture[_MainTex]{
		combine previous * primary
	}
	}
	}
	}
}
2

Start by adding an Alpha property at the top in properties:

_Alpha ("Alpha", Range(0,1)) = 1

In the last/third SetTexture block, update the code to include Alpha

SetTexture[_MainTex]{
    //combine previous * primary
    constantColor(1,1,1,[_Alpha])
    combine previous * constant
}

I’m not sure what primary does and I don’t know how to keep it with previous, I don’t notice a difference without it, so maybe it’s not needed. Sorry if I misinterpret your question, I know you asked how to change the alpha in only MainTexture and not everything, but I guessed that’s you meant. If that’s the case, then I’m not sure.