gistfile1.txt

float4x4 MatrixTransform
	: register(vs, c0)
	: register(ps, c0);

texture2D Texture;
sampler TextureSampler
	: register(s0) = sampler_state { Texture = (Texture); };

const float invSqrtTwo = 0.70710678118654752440084436210485;
float2 XUnit;
float2 YUnit;
float FadeSpeed;
float cmax(float4 color){
	return max(max(color.r, color.g), color.b);
}

void AnalysisVS(
	inout float4 blend : COLOR0,
	inout float2 texCoord : TEXCOORD0,
	inout float4 position : SV_Position)
{
	position = mul(position, MatrixTransform);
}

float4 AnalysisPS(
	in float4 blend : COLOR0,
	in float2 texCoord : TEXCOORD0) : SV_Target0
{
	float4 tl = tex2D(TextureSampler, texCoord - YUnit - XUnit);	// top left
	float4 tc = tex2D(TextureSampler, texCoord - YUnit);			// top center
	float4 tr = tex2D(TextureSampler, texCoord - YUnit + XUnit);	// top right
	float4 ml = tex2D(TextureSampler, texCoord - XUnit);			// middle left
	float4 mc = tex2D(TextureSampler, texCoord);					// middle center
	float4 mr = tex2D(TextureSampler, texCoord + XUnit);			// middle right
	float4 bl = tex2D(TextureSampler, texCoord + YUnit - XUnit);	// bottom left
	float4 bc = tex2D(TextureSampler, texCoord + YUnit);			// bottom center
	float4 br = tex2D(TextureSampler, texCoord + YUnit + XUnit);	// bottom right

	float x = (cmax(tl) * invSqrtTwo + cmax(ml) + cmax(bl) * invSqrtTwo) - (cmax(tr) * invSqrtTwo + cmax(mr) + cmax(br) * invSqrtTwo);
	float y = (cmax(tl) * invSqrtTwo + cmax(tc) + cmax(tr) * invSqrtTwo) - (cmax(bl) * invSqrtTwo + cmax(bc) + cmax(br) * invSqrtTwo);
	float p = cmax(mc);

	// the destination of the pixel we're looking at
	float2 dest = texCoord;// float2(texCoord.x * XUnit.x, texCoord.y * YUnit.y);

	// the offset from the destination back to the source 
	float2 vect = float2(x, y);
	normalize(vect);
	vect.x *= -(1.00 / ((0.001 * FadeSpeed))) * (1 - p);
	vect.y *= -(1.00 / ((0.001 * FadeSpeed))) * (1 - p);

	// the height is just a magic value that is approximated in a linear way
	float height = p / invSqrtTwo;

	// the source is the approximated light source fo the destination, made from the vector, destination and height
	float3 src = float3(dest.x + vect.x, dest.y + vect.y, height);

	return float4(src.x * p, src.y * p, src.z * p, 1.00);
}

technique Analysis
{
	pass
	{
		VertexShader = compile vs_3_0 AnalysisVS();
		PixelShader = compile ps_3_0 AnalysisPS();
	}
}