// ERROR: The given mesh is not closed! Unable to convert to CGAL_Nef_Polyhedron. 

eps = 0.01;
$fn = 100;cb = 15;	// width of collimator border around LEDs
ch = 25;;	// height (thickness) of collimator
g  = 3;			// horizontal gap
inches = 25.4;

module BigShape2D(di) {
	// crossection of collimator
	square([di/2, 2]);
	translate([di/2 - g, 2])
		square([g, 6]);
	square([di/2- cb, ch]);
	polygon([
		[di/2 - cb,   2],
		[di/2 - cb/2, 2],
		[di/2 - cb,  ch/2]
		]);
	}
BigShape2D(150.6);
	
module LEDPattern(n, di) {
	// circular array of "n" LEDs of diameter "D"
	an = 360/n;
	r = di/2 / sin(an/2);
	echo(n, r);
	for (a = [0:an:359])
		rotate([0, 0, a])
			translate([r, 0, 0]) {
				// reduce circle sizes to keep disks from touching
				circle(d = 0.90 * di);
*				rotate([0, 0, -a])
					square([0.7 * di, 0.7 * di], center = true);
*				rotate([0, 0, -a])
					square([0.8 * di, 0.6 * di], center = true);
*				rotate([0, 0, -a])
					polygon([for (a = [0:60:359])
						[0.45 * sin(a) * di, 0.5 * cos(a) * di]]);
				}
	}

module LEDs2D(di) {
	// LED array diameter, in inches
	LEDPattern( 5, 17.5);
	LEDPattern(12, 17.5);
	if (di > 5 * inches) {
		LEDPattern(18, 17.5);
		}
	// registration holes	
	translate([0, di/2 - cb/2, 0])
		circle(2);
	translate([0, -di/2 + cb/2, 0])
		circle(2);
	translate([di/2 - cb/2, 0, 0])
		circle(2);
	}

module Collimator(di)
	difference() {
		rotate_extrude(angle = 360, convexity = 10)
			BigShape2D(di);
		translate([0, 0, -eps])
			linear_extrude(ch + 2*eps)
				LEDs2D(di);
		}

!Collimator(115.9);