Shader "Hidden/Mirza Beig/Image Effects/Sharpen" 
{
	Properties 
	{
		_MainTex ("Base (RGB)", 2D) = "white" {}
		//_strength ("Strength", Range(0.0, 1.0)) = 1.0
	}

	SubShader 
	{
		Pass 
		{							
			CGPROGRAM

			#pragma vertex vert_img
			#pragma fragment frag

			#include "UnityCG.cginc"	
			
			// ...

			uniform sampler2D _MainTex;
						
			uniform float _strength;
			uniform float _edgeMult;			
			
			// ...
						
			float4 frag (v2f_img image) : SV_Target
			{				
				float4 textureColour = tex2D(_MainTex, image.uv);

				// x9 because colour is subtracted 8 times as well as the base.

				float4 sharpenedTextureColour = textureColour * 9.0f;

				// Offset distance proportional to texture size (usually same as screen size).

				float4 offset = 1.0f / (_ScreenParams / _edgeMult);
	
				// Begin offsets counter-clockwise.

				sharpenedTextureColour -= tex2D(_MainTex, image.uv + float2(offset.x,	offset.y));		// Top right.
				sharpenedTextureColour -= tex2D(_MainTex, image.uv + float2(0.0f,		offset.y));		// Up.
				sharpenedTextureColour -= tex2D(_MainTex, image.uv + float2(-offset.x,	offset.y));		// Top left.
				sharpenedTextureColour -= tex2D(_MainTex, image.uv + float2(-offset.x,	0.0f));			// Left.

				sharpenedTextureColour -= tex2D(_MainTex, image.uv + float2(-offset.x,	-offset.y));	// Bottom left.
				sharpenedTextureColour -= tex2D(_MainTex, image.uv + float2(0.0f,		-offset.y));	// Bottom.
				sharpenedTextureColour -= tex2D(_MainTex, image.uv + float2(offset.x,	-offset.y));	// Bottom right.
				sharpenedTextureColour -= tex2D(_MainTex, image.uv + float2(offset.x,	0.0f));			// Right.
				
				// Return mix between original and sharpened.

				return lerp(textureColour, sharpenedTextureColour, _strength);
			}

			ENDCG
		}
	}
}