import postprocess;

uniform Vignette
{
	vec2 coord_scale;
	vec4 optical;
	vec2 optical_range;
	float natural;
};

#pragma MSP stage(fragment)
void main()
{
	vec4 incoming = texture(source, texcoord);
	vec2 r = vertex.xy*coord_scale;
	float r_sq = dot(r, r);

	float vignette = 1.0;
	if(r_sq>=optical_range.y)
		vignette = 0.0;
	else if(r_sq>=optical_range.x)
	{
		float r = sqrt(r_sq)-optical.x;
		float v = (optical.z*acos(r/optical.y)-sqrt(optical.z-r*r)*r);
		vignette = v/optical.w;
	}

	float c_sq = 1/(1+r_sq*natural);
	vignette *= c_sq*c_sq;

	frag_color = vec4(incoming.rgb*vignette, incoming.a);
}