sampler s0 : register(s0);
float4 p0 : register(c0);
float4 p1 : register(c1);

#define width (p0[0])
#define height (p0[1])
#define counter (p0[2])
#define clock (p0[3])
#define one_over_width (p1[0])
#define one_over_height (p1[1])

#define PI acos(-1)

float4 main(float2 tex : TEXCOORD0) : COLOR
{
	float dx = 1/width;
	float dy = 1/height;
	
	float4 c1 = tex2D(s0, tex + float2(-dx,-dy));
	float4 c2 = tex2D(s0, tex + float2(0,-dy));
	float4 c4 = tex2D(s0, tex + float2(-dx,0));
	float4 c6 = tex2D(s0, tex + float2(dx,0));
	float4 c8 = tex2D(s0, tex + float2(0,dy));
	float4 c9 = tex2D(s0, tex + float2(dx,dy));
	
	float4 c0 = (-c1-c2-c4+c6+c8+c9);
	c0 = (c0.r+c0.g+c0.b)/3 + 0.5;
	
	return c0;
}
