diff --git a/src/bin/flat.rs b/src/bin/flat.rs
index 1b9c7c3..46a11df 100644
--- a/src/bin/flat.rs
+++ b/src/bin/flat.rs
@@ -30,37 +30,7 @@ pub fn main() {
 				Box::new(Inside { space: space.clone() }),
 			];
 
-			gc.new_path();
-			let dt = 1.0;
-			let mut s = boundary::Id(0);
-			let mut p = vec2(-500.0, 0.0);
-			let mut v = vec2(3.0, 1.0).normalize();
-			let part = &*parts[s.0 as usize];
-			gc.stroke_color(part.color());
-			gc.move_to(p.x, p.y);
-			for _ in 0..10000 {
-				let part = &*parts[s.0 as usize];
-				let a: Vec2 = -riemann::convolute(riemann::krist(part, p), v);
-				v = v + a * dt;
-				if let Some((id, base, dir)) = part.next(p, v, dt) {
-					gc.stroke();
-					gc.new_path();
-					let pt = part.globalize_loc(p);
-					gc.move_to(pt.x, pt.y);
-					s = id;
-					p = base;
-					v = dir;
-					let part = &*parts[s.0 as usize];
-					let pt = part.globalize_loc(p);
-					gc.stroke_color(part.color());
-					gc.line_to(pt.x, pt.y);
-				} else {
-					p = p + v * dt;
-					let pt = part.globalize_loc(p);
-					gc.line_to(pt.x, pt.y);
-				}
-			}
-			gc.stroke();
+			parts.draw_fan(gc, vec2(-500.0, 0.0), vec2(1.0, 0.0), 1.0);
 		});
 	});
 }
@@ -104,24 +74,66 @@ impl SpaceVisual for Inside {
 	}
 }
 
-fn draw_ray(gc: &mut Vec<Draw>, space: &impl Metric, base: Vec2, dir: Vec2) {
-	let dir = space.globalize(base, dir);
-	gc.new_path();
-	gc.move_to(base.x, base.y);
-	for pt in trace_iter(space, base, dir, 1.0).take(10000) {
-		gc.line_to(pt.x, pt.y);
-		if pt.abs().cmpgt(Vec2::splat(1000.0)).any() {
-			break;
+impl Rayable for [Box<dyn SpacePart>] {
+	fn draw_ray(&self, gc: &mut Vec<Draw>, base: Vec2, dir: Vec2) {
+		gc.new_path();
+		let dt = 1.0;
+		let mut s = boundary::Id(0);
+		let mut p = base;
+		let mut v = dir.normalize();
+		let part = &*self[s.0 as usize];
+		gc.stroke_color(part.color());
+		gc.move_to(p.x, p.y);
+		for _ in 0..10000 {
+			let part = &*self[s.0 as usize];
+			let a: Vec2 = -riemann::convolute(riemann::krist(part, p), v);
+			v = v + a * dt;
+			if let Some((id, base, dir)) = part.next(p, v, dt) {
+				gc.stroke();
+				gc.new_path();
+				let pt = part.globalize_loc(p);
+				gc.move_to(pt.x, pt.y);
+				s = id;
+				p = base;
+				v = dir;
+				let part = &*self[s.0 as usize];
+				let pt = part.globalize_loc(p);
+				gc.stroke_color(part.color());
+				gc.line_to(pt.x, pt.y);
+			} else {
+				p = p + v * dt;
+				let pt = part.globalize_loc(p);
+				gc.line_to(pt.x, pt.y);
+			}
 		}
+		gc.stroke();
 	}
-	gc.stroke();
 }
 
-fn draw_fan(gc: &mut Vec<Draw>, space: &impl Metric, base: Vec2, dir: Vec2, spread: f32) {
-	let dir = dir.normalize();
-	let v = vec2(-dir.y, dir.x);
-	for y in itertools_num::linspace(-spread, spread, 101) {
-		draw_ray(gc, space, base, dir + y * v);
+trait Rayable {
+	fn draw_ray(&self, gc: &mut Vec<Draw>, base: Vec2, dir: Vec2);
+
+	fn draw_fan(&self, gc: &mut Vec<Draw>, base: Vec2, dir: Vec2, spread: f32) {
+		let dir = dir.normalize();
+		let v = vec2(-dir.y, dir.x);
+		for y in itertools_num::linspace(-spread, spread, 101) {
+			self.draw_ray(gc, base, dir + y * v);
+		}
+	}
+}
+
+impl<T: Metric> Rayable for T {
+	fn draw_ray(&self, gc: &mut Vec<Draw>, base: Vec2, dir: Vec2) {
+		let dir = self.globalize(base, dir);
+		gc.new_path();
+		gc.move_to(base.x, base.y);
+		for pt in trace_iter(self, base, dir, 1.0).take(10000) {
+			gc.line_to(pt.x, pt.y);
+			if pt.abs().cmpgt(Vec2::splat(1000.0)).any() {
+				break;
+			}
+		}
+		gc.stroke();
 	}
 }
 
@@ -141,9 +153,9 @@ impl Renderable for Coil {
 		gc.fill();
 		gc.line_width(0.5);
 		gc.stroke_color(Color::Rgba(1.0, 0.5, 0.0, 1.0));
-		draw_fan(gc, self, vec2(-500.0, 0.0), vec2(1.0, 0.0), 1.0);
+		self.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));
-		draw_fan(gc, self, vec2(0.0, self.r), vec2(1.0, 0.0), 1.0);
+		self.draw_fan(gc, vec2(0.0, self.r), vec2(1.0, 0.0), 1.0);
 	}
 }
 
@@ -157,9 +169,9 @@ impl Renderable for Rect {
 		gc.fill();
 		gc.line_width(0.5);
 		gc.stroke_color(Color::Rgba(1.0, 0.5, 0.0, 1.0));
-		draw_fan(gc, self, vec2(-500.0, 0.0), vec2(1.0, 0.0), 1.0);
+		self.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));
-		draw_fan(gc, self, vec2(0.0, -0.5 * self.r.y), vec2(1.0, 1.0), 1.0);
+		self.draw_fan(gc, vec2(0.0, -0.5 * self.r.y), vec2(1.0, 1.0), 1.0);
 	}
 }