#define pi 3.141592653589793238462643383279
#define twopi (pi * 2.0)
uniform float minRad;
uniform float maxRad;
varying vec2 rcoords;

void main() {
	float r = length(rcoords);
	float width = 0.7;
	if(r >= 1.0 || r < 1.0 - width)
		discard;

	float ang = atan(rcoords.y, rcoords.x);
	if(ang < minRad && ang > maxRad - twopi)
		discard;
	if(ang > maxRad && ang < minRad + twopi)
		discard;
	
	float bdist = r - (1.0 - width);

	vec4 col = gl_Color;
	if(r < 0.95)
		col.a *= 0.5;
	else if(r < 0.96)
		col.a *= 0.5 + ((r - 0.95) / 0.01) * 0.5;
	else if(r > 0.99)
		col.a *= (1.0 - r) / 0.01;

	col.a *= bdist / width;

	float adist = min(abs(ang - minRad), abs(ang - maxRad));
	if(adist < 0.02)
		col.a *= adist / 0.02;
	
	gl_FragColor = col;
}