// gray offset
// (c) 2005 Holger Grahn 
float time=0;
float sampleDist = 1.0f/512.0f;  // distance one pixel in u/v

float displaceAmount=0.2;

sampler2D image : register(s0);


float4 main(
	float4 Pos : POSITION,
	float2 texCoord: TEXCOORD0) : COLOR 
{
	float4 img = tex2D(image, texCoord);

	// convert to gray 
	float2 sum;
	sum.x = dot(img, float4(0.90f, 0.4, 0.2f, 0.0f))-0.5;
	sum.y = dot(img, float4(0.2f, 0.4f, 0.9f, 1.0f))-0.5;
	float fac=displaceAmount;
	//fac *= pow(sin(time*3.1414)-0.5,1.7);
	fac *= pow(time,1.7);
	//img = tex2D(image, float2(texCoord.x+exp(fac*sum.x),texCoord.y+fac*sum.y));
	img = tex2D(image, float2(texCoord.x+(fac*sum.x),texCoord.y+fac*sum.y));
	return img;
}