uniform float4x4 ViewProj;
uniform texture2d image;
uniform float2 texel;
uniform int widthHalf;
uniform int width;

sampler_state textureSampler {
	Filter    = Point;
	AddressU  = Clamp;
	AddressV  = Clamp;
};

struct VertDataIn {
	float4 pos : POSITION;
	float2 uv  : TEXCOORD0;
};

struct VertDataOut {
	float4 pos : POSITION;
	float2 uv  : TEXCOORD0;
};

VertDataOut VSDefault(VertDataIn v_in)
{
	VertDataOut vert_out;
	vert_out.pos = mul(float4(v_in.pos.xyz, 1.0), ViewProj);
	vert_out.uv  = v_in.uv;
	return vert_out;
}

// Gaussian Blur
float Gaussian(float x, float deviation) {
	return (1.0 / sqrt(2.0 * 3.141592 * deviation)) * exp(-((x * x) / (2.0 * deviation)));	
}

float4 PSGaussian(VertDataOut v_in) : TARGET
{
	float4 rgba = float4(0, 0, 0, 0);	
	for (int k = -widthHalf; k <= widthHalf; k++) {
		float4 smpl = image.Sample(textureSampler, v_in.uv + (texel * k));
		smpl *= Gaussian(k / width, 1.0);
		rgba += smpl;
	}
	return rgba;
}

technique Draw
{
	pass
	{
		vertex_shader = VSDefault(v_in);
		pixel_shader  = PSGaussian(v_in);
	}
}