Add shaders

Sources/Shaders/BasicCoverage.cginc

@@ -0,0 +1,25 @@
+	
+	uniform sampler2D _MainTex;
+	uniform float4    _GS_SnowData1;	// x = relief, y = occlusion, z = glitter, w = brightness
+	uniform float4    _GS_SnowData2;	// x = minimum altitude, y = altitude scattering, z = coverage extension
+
+	struct Input {
+		float2 uv_MainTex;
+    	float3 worldPos;
+		float3 worldNormal;
+	};
+
+	// get snow coverage on simple forms
+	void SetBasicCoverage(Input IN, inout SurfaceOutput o) { 
+
+		// prevent snow on sides and below minimum altitude
+		float3 wsNormal = IN.worldNormal; 
+		float ny = wsNormal.y - 0.2;
+		float flatSurface = saturate(ny * 10.0);
+		float minAltitude = saturate( IN.worldPos.y - _GS_SnowData2.x);
+		float snowCover   = minAltitude * flatSurface;
+		
+		// pass color data to output shader
+		o.Albedo = 1.0; // _GS_SnowData1.www;
+		o.Alpha *= snowCover;
+	}