uniform float4x4 ViewProj;
uniform texture2d image;

uniform float2 inv_size;
uniform float blur_size;

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

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

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

VertDataOut VSOttorGlow(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;
}

float GetColorAlpha(float angle, float dist, float2 uv)
{
	float radian = radians(angle);
	float2 pos = uv + float2(dist * cos(radian) * inv_size.x, dist * sin(radian) * inv_size.y);
	float4 color = image.Sample(textureSampler, pos);
	return color.a;
}

float GetAverageAlpha(float dist, float2 uv)
{
	float totalAlpha = 0.0;
	totalAlpha += GetColorAlpha(0.0, dist, uv);
	totalAlpha += GetColorAlpha(30.0, dist, uv);
	totalAlpha += GetColorAlpha(60.0, dist, uv);
	totalAlpha += GetColorAlpha(90.0, dist, uv);
	totalAlpha += GetColorAlpha(120.0, dist, uv);
	totalAlpha += GetColorAlpha(150.0, dist, uv);
	totalAlpha += GetColorAlpha(180.0, dist, uv);
	totalAlpha += GetColorAlpha(210.0, dist, uv);
	totalAlpha += GetColorAlpha(240.0, dist, uv);
	totalAlpha += GetColorAlpha(270.0, dist, uv);
	totalAlpha += GetColorAlpha(300.0, dist, uv);
	totalAlpha += GetColorAlpha(330.0, dist, uv);
	return totalAlpha * 0.0833;
}

float GetGlowAlpha(float2 uv)
{
	float glow_size = blur_size;
	float totalAlpha = 0.0;
	totalAlpha += GetAverageAlpha(glow_size * 0.1, uv);
	totalAlpha += GetAverageAlpha(glow_size * 0.2, uv);
	totalAlpha += GetAverageAlpha(glow_size * 0.3, uv);
	totalAlpha += GetAverageAlpha(glow_size * 0.4, uv);
	totalAlpha += GetAverageAlpha(glow_size * 0.5, uv);
	totalAlpha += GetAverageAlpha(glow_size * 0.6, uv);
	totalAlpha += GetAverageAlpha(glow_size * 0.7, uv);
	totalAlpha += GetAverageAlpha(glow_size * 0.8, uv);
	totalAlpha += GetAverageAlpha(glow_size * 0.9, uv);
	totalAlpha += GetAverageAlpha(glow_size * 1.0, uv);
	return totalAlpha * 0.1;
}

float4 PSOttorGlow(VertDataOut v_in) : TARGET
{
	float4 color = image.Sample(textureSampler, v_in.uv);
	color.a = GetGlowAlpha(v_in.uv) * 0.6;
	return color;
}

technique Draw
{
	pass
	{
		vertex_shader = VSOttorGlow(v_in);
		pixel_shader = PSOttorGlow(v_in);
	}
}