diff --git a/src/bin/flat.rs b/src/bin/flat.rs
index 8a6b76a..a6e1789 100644
--- a/src/bin/flat.rs
+++ b/src/bin/flat.rs
@@ -28,7 +28,16 @@ pub fn main() {
 		let canvas = create_drawing_window("Refraction");
 		canvas.draw(|gc| {
 			gc.canvas_height(1000.0);
+			gc.line_width(0.5);
+
+			// gc.canvas_height(100.0);
+			// gc.center_region(-100.0, -200.0, 100.0, 0.0);
+			// gc.line_width(0.1);
+
 			space.draw_background(gc);
+
+			// gc.stroke_color(Color::Rgba(0.5, 1.0, 0.0, 1.0));
+			// space.draw_fan(gc, vec2(0.0, -0.5 * space.external_halflength), vec2(1.0, 1.0), 1.0);
 			space.draw_rays(gc, &space);
 
 			let space = Rc::new(space);
@@ -38,6 +47,8 @@ pub fn main() {
 				Box::new(Inside { space: space.clone() }),
 			];
 			space.draw_rays(gc, parts.as_slice());
+			// gc.stroke_color(Color::Rgba(1.0, 0.0, 1.0, 1.0));
+			// parts.draw_fan(gc, vec2(0.0, space.u(-0.5 * space.external_halflength)), vec2(1.0, 1.0), 1.0);
 		});
 	});
 }
@@ -162,7 +173,6 @@ impl Interesting for Coil {
 	}
 
 	fn draw_rays(&self, gc: &mut Vec<Draw>, tracer: &(impl Rayable + ?Sized)) {
-		gc.line_width(0.5);
 		gc.stroke_color(Color::Rgba(1.0, 0.5, 0.0, 1.0));
 		tracer.draw_fan(gc, vec2(-500.0, 0.0), vec2(1.0, 0.0), 1.0);
 		gc.stroke_color(Color::Rgba(0.0, 0.5, 1.0, 1.0));
@@ -181,9 +191,10 @@ impl Interesting for Rect {
 	}
 
 	fn draw_rays(&self, gc: &mut Vec<Draw>, tracer: &(impl Rayable + ?Sized)) {
-		gc.line_width(0.5);
 		gc.stroke_color(Color::Rgba(1.0, 0.5, 0.0, 1.0));
 		tracer.draw_fan(gc, vec2(-500.0, 0.0), vec2(1.0, 0.0), 1.0);
+		gc.stroke_color(Color::Rgba(0.5, 1.0, 0.0, 1.0));
+		tracer.draw_fan(gc, vec2(0.0, -0.5 * self.external_halflength), vec2(1.0, 1.0), 1.0);
 		gc.stroke_color(Color::Rgba(0.0, 0.5, 1.0, 1.0));
 		tracer.draw_fan(gc, vec2(0.0, -0.5 * self.external_halflength), vec2(1.0, 1.0), 1.0);
 		gc.stroke_color(Color::Rgba(0.2, 0.7, 0.0, 1.0));