Shader "Unlit/Transparent Colored Gray"
{
Properties
{
_MainTex ("Base (RGB) Gray, Alpha (A)", 2D) = "white" {}
}

SubShader
{
LOD 100

Tags
{
"Queue" = "Transparent"
"IgnoreProjector" = "True"
"RenderType" = "Transparent"
}

Pass
{
Cull Off
Lighting Off
ZWrite Off
Fog { Mode Off }
Offset -1, -1
ColorMask RGB
AlphaTest Greater .01
Blend SrcAlpha OneMinusSrcAlpha
ColorMaterial AmbientAndDiffuse

CGPROGRAM
#pragma vertex vert
#pragma fragment frag
#pragma fragmentoption ARB_precision_hint_fastest

#include "UnityCG.cginc"

sampler2D _MainTex;
fixed4 _Color;

struct appdata_t
{
float4 vertex : POSITION;
fixed4 color : COLOR;
float2 texcoord : TEXCOORD0;
};

struct v2f
{
float4 vertex : POSITION;
fixed4 color : COLOR;
float2 texcoord : TEXCOORD0;
fixed gray : TEXCOORD1;
};

float4 _MainTex_ST;

v2f vert (appdata_t v)
{
v2f o;
o.vertex = mul(UNITY_MATRIX_MVP, v.vertex);
o.color = v.color;
o.gray = dot(v.color, fixed4(1,1,1,0));
o.texcoord = TRANSFORM_TEX(v.texcoord, _MainTex);
return o;
}

fixed4 frag (v2f i) : COLOR
{
fixed4 col;
if (i.gray == 0)
{
col = tex2D(_MainTex, i.texcoord);
col.rgb = dot(col.rgb, fixed3(.222,.707,.071));
}
else
{
col = tex2D(_MainTex, i.texcoord) * i.color;
}
return col;
}
ENDCG
}
}
}