Shader "MY/Shadow"
{
	Properties{
		_ShadowTex("Shadow", 2D) = "gray" {}
		_FadeTex("FadeTex", 2D) = "white" {}
		_Alpha("Alpha", Range(0,1)) = 0.6
	}
		SubShader{
			Tags { "Queue" = "Transparent" }
			Pass {
				ZWrite Off
				Fog { Mode Off }
				ColorMask RGB
				Blend DstColor Zero

				CGPROGRAM
				#pragma vertex vert
				#pragma fragment frag
				#include "UnityCG.cginc"

				struct v2f {
					float4 pos:POSITION;
					float4 sproj:TEXCOORD0;
					float4 fproj:TEXCOORD1;
				};

				float4x4 unity_Projector;
				float4x4 unity_ProjectorClip;
				fixed _Alpha;
				sampler2D _ShadowTex;
				sampler2D _FadeTex;

				v2f vert(float4 vertex:POSITION) {
					v2f o;
					o.pos = UnityObjectToClipPos(vertex);
					o.sproj = mul(unity_Projector, vertex);
					o.fproj = mul(unity_ProjectorClip, vertex);
					return o;
				}

				fixed4 frag(v2f i) :COLOR{
					fixed4 c = tex2Dproj(_ShadowTex, UNITY_PROJ_COORD(i.sproj));
					fixed fade = tex2Dproj(_FadeTex, UNITY_PROJ_COORD(i.sproj)).g;
					fixed4 result;
					result.rgb = lerp(fixed3(1, 1, 1), 1 - c.a, _Alpha);
					result.rgb += 1 - fade;
					result.a = 1;
					return result;
				}

				ENDCG
			}
		}
}