// OBS Default
uniform float4x4 ViewProj;

// Settings (Shared)
uniform texture2d u_image;
uniform float2 u_imageSize;
uniform float2 u_imageTexel;
uniform int u_radius;
uniform int u_diameter;
uniform float2 u_texelDelta;

// Settings (Private)
uniform float bilateralSmoothing;
uniform float bilateralSharpness;

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;
}

// Bilateral Blur
float Bilateral(float x, float sigma)
{
	return 0.39894 * exp(-0.5 * (x*x) / (sigma*sigma)) / sigma;
}

float Bilateral3(float3 v, float sigma)
{
	// First part is Gaussian function (1.0 / (o * sqrt(2.0 * pivalue))) with o = 1
	return 0.39894 * exp(-0.5 * dot(v,v) / (sigma*sigma)) / sigma;
}

float4 BilateralBlur(float2 p_uv, float2 p_radius,
 texture2d p_image, float2 p_imageTexel) {
	float2 l_uvoffset = float2(0, 0);
}

float4 PSBilateral(VertDataOut v_in) : TARGET
{
	float2 l_uv = float2(0, 0);

	float Z = 0.0;
	float bZ = 1.0 / Bilateral(0.0, bilateralSharpness);
	float4 source = u_image.Sample(textureSampler, v_in.uv);
	float3 color = float3(0, 0, 0);
	for (int k = 1; k <= u_radius; k++) {
		// Advance UV by one texel.
		l_uv += u_texelDelta;

		// Bilateral Kernel
		float bKernel = Bilateral(abs(k), bilateralSmoothing);
		bKernel *= bKernel;
		float bZKernel = bZ  * bKernel;

		// Sample Color
		float3 l_p = u_image.Sample(textureSampler, v_in.uv + l_uv).rgb;
		float3 l_n = u_image.Sample(textureSampler, v_in.uv - l_uv).rgb;

		// Bilateral Stuff
		float l_factor_p = Bilateral3(l_p - source.rgb, bilateralSharpness) * bZKernel;
		float l_factor_n = Bilateral3(l_n - source.rgb, bilateralSharpness) * bZKernel;
		Z = Z + l_factor_p + l_factor_n;

		// Store Color
		color += l_p * l_factor_p;
		color += l_n * l_factor_n;
	}

	return float4(color.rgb / Z, source.a);
}

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