// $MinimumShaderProfile: ps_4_0

Texture2D tex : register(t0);
SamplerState samp : register(s0);

cbuffer PS_CONSTANTS : register(b0)
{
	float  px;
	float  py;
	float2 wh;
	uint   counter;
	float  clock;
};

/* Parameters */

// for the blur filter
#define mean 0.6
#define dx (mean * px)
#define dy (mean * py)

#define CoefBlur 2
#define CoefOrig (1 + CoefBlur)

// for the sharpen filter
#define SharpenEdge  0.2
#define Sharpen_val0 2
#define Sharpen_val1 ((Sharpen_val0 - 1) / 8.0)

float4 main(float4 pos : SV_POSITION, float2 coord : TEXCOORD) : SV_Target
{
	// get original pixel
	float4 orig = tex.Sample(samp, coord);

	// compute blurred image (gaussian filter)
	float4 c1 = tex.Sample(samp, coord + float2(-dx, -dy));
	float4 c2 = tex.Sample(samp, coord + float2(  0, -dy));
	float4 c3 = tex.Sample(samp, coord + float2( dx, -dy));
	float4 c4 = tex.Sample(samp, coord + float2(-dx,   0));
	float4 c5 = tex.Sample(samp, coord + float2( dx,   0));
	float4 c6 = tex.Sample(samp, coord + float2(-dx,  dy));
	float4 c7 = tex.Sample(samp, coord + float2(  0,  dy));
	float4 c8 = tex.Sample(samp, coord + float2( dx,  dy));

	// gaussian filter
	// [ 1, 2, 1 ]
	// [ 2, 4, 2 ]
	// [ 1, 2, 1 ]
	// to normalize the values, we need to divide by the coeff sum
	// 1 / (1+2+1+2+4+2+1+2+1) = 1 / 16 = 0.0625
	float4 flou = (c1 + c3 + c6 + c8 + 2 * (c2 + c4 + c5 + c7) + 4 * orig) * 0.0625;

	// substract blurred image from original image
	float4 corrected = CoefOrig * orig - CoefBlur * flou;

	// edge detection
	// Get neighbor points
	// [ c1,   c2, c3 ]
	// [ c4, orig, c5 ]
	// [ c6,   c7, c8 ]
	c1 = tex.Sample(samp, coord + float2(-px, -py));
	c2 = tex.Sample(samp, coord + float2(  0, -py));
	c3 = tex.Sample(samp, coord + float2( px, -py));
	c4 = tex.Sample(samp, coord + float2(-px,   0));
	c5 = tex.Sample(samp, coord + float2( px,   0));
	c6 = tex.Sample(samp, coord + float2(-px,  py));
	c7 = tex.Sample(samp, coord + float2(  0,  py));
	c8 = tex.Sample(samp, coord + float2( px,  py));

	// using Sobel filter
	// horizontal gradient
	// [ -1, 0, 1 ]
	// [ -2, 0, 2 ]
	// [ -1, 0, 1 ]
	float delta1 = (c3 + 2 * c5 + c8) - (c1 + 2 * c4 + c6);

	// vertical gradient
	// [ -1, - 2, -1 ]
	// [  0,   0,  0 ]
	// [  1,   2,  1 ]
	float delta2 = (c6 + 2 * c7 + c8) - (c1 + 2 * c2 + c3);

	// computation
	if (sqrt(mul(delta1, delta1) + mul(delta2, delta2)) > SharpenEdge) {
		// if we have an edge, use sharpen
		//return  float4(1,0,0,0);
		return orig * Sharpen_val0 - (c1 + c2 + c3 + c4 + c5 + c6 + c7 + c8) * Sharpen_val1;
	} else {
		// else return corrected image
		return corrected;
	}
}
