How to make projector/light shader "alpha enabled"?

Questions & Answers
1

I’m using a projector to project a series of images which need to be fade in and fade out in order to look as a smooth animation.
I’m wondering how would I inject alpha possibilities into this shader.

cheers,

2

I’ve slightly tinkered with the standard Projector/light shader of unity 5, and this is what I use:

Shader "Projector/Light" {
	Properties {
		_Color ("Main Color", Color) = (1,1,1,1)
		_ShadowTex ("Cookie", 2D) = "" {}
		_FalloffTex ("FallOff", 2D) = "" {}
	}
	
	Subshader {
		Tags {"Queue"="Transparent"}
		Pass {
			ZWrite Off
			ColorMask RGB
			Blend DstColor One
			Offset -1, -1
	
			CGPROGRAM
			#pragma vertex vert
			#pragma fragment frag
			#pragma multi_compile_fog
			#include "UnityCG.cginc"
			
			struct v2f {
				float4 uvShadow : TEXCOORD0;
				float4 uvFalloff : TEXCOORD1;
				UNITY_FOG_COORDS(2)
				float4 pos : SV_POSITION;
			};
			
			float4x4 _Projector;
			float4x4 _ProjectorClip;
			
			v2f vert (float4 vertex : POSITION)
			{
				v2f o;
				o.pos = mul (UNITY_MATRIX_MVP, vertex);
				o.uvShadow = mul (_Projector, vertex);
				o.uvFalloff = mul (_ProjectorClip, vertex);
				UNITY_TRANSFER_FOG(o,o.pos);
				return o;
			}
			
			fixed4 _Color;
			sampler2D _ShadowTex;
			sampler2D _FalloffTex;
			
			fixed4 frag (v2f i) : SV_Target
			{
				fixed4 texS = tex2Dproj (_ShadowTex, UNITY_PROJ_COORD(i.uvShadow));
				texS.rgb *= _Color.rgb;
				texS.a = (1.0-texS.a);
	
				fixed4 texF = tex2Dproj (_FalloffTex, UNITY_PROJ_COORD(i.uvFalloff));
                                // Added multiplication by _Color.a here
				fixed4 res = texS * texF.a * _Color.a;

				UNITY_APPLY_FOG_COLOR(i.fogCoord, res, fixed4(0,0,0,0));
				return res;
			}
			ENDCG
		}
	}
}
3

Thanks, this made a great projector light, but I can’t seem to access the alpha channels to fade it out.
I tried a fading script in c# but it doesn’t alter the alpha channel. Do I need to alter the shader in some way to do that?