Add shaders

Sources/Shaders/MaskWrite.shader

@@ -0,0 +1,57 @@
+Shader "GlobalSnow/DeferredMaskWrite" {
+SubShader {
+
+	Tags { "DisableBatching" = "True" }
+	Cull [_EraseCullMode]
+
+	CGINCLUDE
+	#include "UnityCG.cginc"
+    #include "GlobalSnowDeferredOptions.cginc"
+    
+    struct appdata {
+    	float4 vertex : POSITION;
+        float2 uv     : TEXCOORD0;
+    };
+
+	struct v2f {
+	    float4 pos : SV_POSITION;
+		float2 uv  : TEXCOORD0;
+	};
+
+	sampler2D _GS_MaskTexture;
+	float4 _GS_MaskTexture_ST;
+	fixed _GS_MaskCutOff;
+
+	v2f vert(appdata v) {
+    	v2f o;
+        APPLY_VERTEX_MODIFIER(v)
+    	o.pos = UnityObjectToClipPos(v.vertex);
+		o.uv = TRANSFORM_TEX(v.uv, _GS_MaskTexture);
+		return o;
+	}	
+	
+	fixed4 frag(v2f i): SV_Target {
+		fixed4 color = tex2D(_GS_MaskTexture, i.uv);
+		color.a = 1.0 - color.a;
+		clip(color.a - _GS_MaskCutOff);
+		return fixed4(0,0,0,0);
+	}	
+	
+	
+	ENDCG
+
+	Pass { 
+       	Fog { Mode Off }
+       	ColorMask 0
+		CGPROGRAM
+		#pragma target 3.0
+   		#pragma fragmentoption ARB_precision_hint_fastest
+		#pragma vertex vert
+		#pragma fragment frag
+		ENDCG
+	}
+	
+}
+
+Fallback Off
+}