Shader "Hidden/NoiseAndGrain" {
	Properties {
		_MainTex ("Base (RGB)", 2D) = "white" {}
		_NoiseTex ("Noise (RGB)", 2D) = "white" {}
	}
	
	CGINCLUDE

		#include "UnityCG.cginc"

		sampler2D _MainTex;
		sampler2D _NoiseTex;
		float4 _NoiseTex_TexelSize;
		
		uniform float4 _MainTex_TexelSize;

		uniform float3 _NoisePerChannel;
		uniform float3 _NoiseTilingPerChannel;
		uniform float3 _NoiseAmount;
		uniform float3 _ThreshholdRGB;
		uniform float3 _MidGrey;	
		
		struct v2f 
		{
			float4 pos : SV_POSITION;
			float2 uv_screen : TEXCOORD0;
			float4 uvRg : TEXCOORD1;
			float2 uvB : TEXCOORD2;
		};
		
		struct appdata_img2 
		{
		    float4 vertex : POSITION;
		    float2 texcoord : TEXCOORD0;
		    float2 texcoord1 : TEXCOORD1;
		};		

		inline float3 Overlay(float3 m, float3 color) {
			color = saturate(color);
			float3 check = step(float3(0.5,0.5,0.5), color.rgb);
			float3 result = check * (float3(1,1,1) - ((float3(1,1,1) - 2*(color.rgb-0.5)) * (1-m.rgb))); 
			result += (1-check) * (2*color.rgb) * m.rgb;
			return result;
		}			
						
		v2f vert (appdata_img2 v)
		{
			v2f o;
			
			o.pos = UnityObjectToClipPos(v.vertex);	
			
		#if UNITY_UV_STARTS_AT_TOP
			o.uv_screen = v.vertex.xyxy;
			if (_MainTex_TexelSize.y < 0)
        		o.uv_screen.y = 1-o.uv_screen.y;
		#else
        		o.uv_screen = v.vertex.xy;
		#endif

			o.uv_screen = UnityStereoTransformScreenSpaceTex(o.uv_screen);

			// different tiling for 3 channels
			o.uvRg = v.texcoord.xyxy + v.texcoord1.xyxy * _NoiseTilingPerChannel.rrgg * _NoiseTex_TexelSize.xyxy;
			o.uvB = v.texcoord.xy + v.texcoord1.xy * _NoiseTilingPerChannel.bb * _NoiseTex_TexelSize.xy;

			return o; 
		}

		float4 frag ( v2f i ) : SV_Target
		{	
			float4 color = (tex2D (_MainTex, i.uv_screen.xy));
			
			// black & white intensities
			float2 blackWhiteCurve = Luminance(color.rgb) - _MidGrey.x; // maybe tweak middle grey
			blackWhiteCurve.xy = saturate(blackWhiteCurve.xy * _MidGrey.yz); //float2(1.0/0.8, -1.0/0.2));

			float finalIntensity = _NoiseAmount.x + max(0.0f, dot(_NoiseAmount.zy, blackWhiteCurve.xy));
			
			// fetching & scaling noise (COMPILER BUG WORKAROUND)
			float3 m = float3(0,0,0);
			m += (tex2D(_NoiseTex, i.uvRg.xy) * float4(1,0,0,0)).rgb;
			m += (tex2D(_NoiseTex, i.uvRg.zw) * float4(0,1,0,0)).rgb;
			m += (tex2D(_NoiseTex, i.uvB.xy) * float4(0,0,1,0)).rgb;

			m = saturate(lerp(float3(0.5,0.5,0.5), m, _NoisePerChannel.rgb * float3(finalIntensity,finalIntensity,finalIntensity) ));

			return float4(Overlay(m, color.rgb), color.a);
		} 

		float4 fragTmp ( v2f i ) : SV_Target
		{	
			float4 color = (tex2D (_MainTex, i.uv_screen.xy));
			
			// black & white intensities
			float2 blackWhiteCurve = Luminance(color.rgb) - _MidGrey.x; // maybe tweak middle grey
			blackWhiteCurve.xy = saturate(blackWhiteCurve.xy * _MidGrey.yz); //float2(1.0/0.8, -1.0/0.2));

			float finalIntensity = _NoiseAmount.x + max(0.0f, dot(_NoiseAmount.zy, blackWhiteCurve.xy));
			
			// fetching & scaling noise (COMPILER BUG WORKAROUND)
			float3 m = float3(0,0,0);
			m += (tex2D(_NoiseTex, i.uvRg.xy) * float4(1,0,0,0)).rgb;
			m += (tex2D(_NoiseTex, i.uvRg.zw) * float4(0,1,0,0)).rgb;
			m += (tex2D(_NoiseTex, i.uvB.xy) * float4(0,0,1,0)).rgb;

			m = saturate(lerp(float3(0.5,0.5,0.5), m, _NoisePerChannel.rgb * float3(finalIntensity,finalIntensity,finalIntensity)));

			return float4(m.rgb, color.a);
		} 			

		float4 fragOverlayBlend	( v2f i ) : SV_Target
		{	
			float4 color = tex2D(_MainTex, i.uv_screen.xy);
			float4 m = tex2D(_NoiseTex, i.uv_screen.xy);
			
			return float4(Overlay(m, color.rgb), color.a);
		}	
	
	ENDCG
	
	SubShader {
		ZTest Always Cull Off ZWrite Off Blend Off
	  
		Pass {
	
		CGPROGRAM
		
		#pragma vertex vert
		#pragma fragment frag
		
		ENDCG
		 
		}	

		Pass {
	
		CGPROGRAM
		
		#pragma vertex vert
		#pragma fragment fragOverlayBlend
		
		ENDCG
		 
		}	

		Pass {
	
		CGPROGRAM
		
		#pragma vertex vert
		#pragma fragment fragTmp
		
		ENDCG
		 
		}				
	}
	FallBack Off
}