Shader "CRLuo/RGBAMask3"
{
	Properties
	{
		//_MainTex ("黑色默认纹理", 2D) = "white" {}
		_RTex ("红色通道图像", 2D) = "white" {}
		_GTex ("绿色通道图像", 2D) = "white" {}
		_BTex ("蓝色通道图像", 2D) = "white" {}
		//_ATex ("透明通道图像", 2D) = "white" {}
		_MaskTex ("RGBA遮罩图像", 2D) = "white" {}
	}
	SubShader
	{
		Tags { "RenderType"="Opaque" }
		LOD 100

		Pass
		{
			CGPROGRAM
			#pragma vertex vert
			#pragma fragment frag
			// make fog work
			#pragma multi_compile_fog
			#pragma multi_compile LIGHTMAP_ON LIGHTMAP_OFF

			#include "UnityCG.cginc"

			struct appdata
			{
				float4 vertex : POSITION;
				float2 Muv : TEXCOORD0;
				#if LIGHTMAP_ON
				float3 uv1 : TEXCOORD1;
				#endif
			};

			struct v2f
			{
				float2 Muv : TEXCOORD0;
				#if LIGHTMAP_ON
				//lightmap
				float2 uv0 : TEXCOORD1;
				#endif
				UNITY_FOG_COORDS(2)
				float4 vertex : SV_POSITION;
			};

			//sampler2D _MainTex;
			//float4 _MainTex_ST;

			sampler2D _RTex;
			float4 _RTex_ST;

			sampler2D _GTex;
			float4 _GTex_ST;

			sampler2D _BTex;
			float4 _BTex_ST;

			//sampler2D _ATex;
			//float4 _ATex_ST;

			sampler2D _MaskTex;
			float4 _MaskTex_ST;


			v2f vert (appdata v)
			{
				v2f o;
				UNITY_SETUP_INSTANCE_ID(v);
            	UNITY_INITIALIZE_VERTEX_OUTPUT_STEREO(o);
				o.vertex = UnityObjectToClipPos(v.vertex);
				o.Muv = TRANSFORM_TEX(v.Muv, _MaskTex);
				UNITY_TRANSFER_FOG(o,o.vertex);

				#if LIGHTMAP_ON
				o.uv0 = v.uv1.xy * unity_LightmapST.xy + unity_LightmapST.zw;
				#endif

				return o;
			}
			
			fixed4 frag (v2f i) : SV_Target
			{

				//float2 MainUV = float2(i.Muv.x * _MainTex_ST.x,i.Muv.y * _MainTex_ST.y);
				float2 RUV = float2(i.Muv.x * _RTex_ST.x,i.Muv.y * _RTex_ST.y);
				fixed4 col = tex2D(_RTex, RUV);
				//col = col lerp(tex2D(_MainTex, MainUV),tex2D(_RTex, RUV),tex2D(_MaskTex, i.Muv).r);

				float2 GUV = float2(i.Muv.x * _GTex_ST.x,i.Muv.y * _GTex_ST.y);
				col = lerp(col,tex2D(_GTex, GUV),tex2D(_MaskTex, i.Muv).g);

				float2 BUV = float2(i.Muv.x * _BTex_ST.x,i.Muv.y * _BTex_ST.y);
				col = lerp(col,tex2D(_BTex, BUV),tex2D(_MaskTex, i.Muv).b);

				//float2 AUV = float2(i.Muv.x * _ATex_ST.x,i.Muv.y * _ATex_ST.y);
				//col = lerp(col,tex2D(_ATex, AUV),tex2D(_MaskTex, i.Muv).a);

				#if LIGHTMAP_ON
				fixed4 coll;
            	// Fetch lightmap
            	half4 bakedColorTex = UNITY_SAMPLE_TEX2D(unity_Lightmap, i.uv0.xy);
            	coll.rgb = DecodeLightmap(bakedColorTex);
            	col.rgb = col.rgb * coll.rgb;
            	#endif

				// apply fog
				UNITY_APPLY_FOG(i.fogCoord, col);
				return col;
			}

			ENDCG
		}
	}
}