diff --git a/src/bin/flat.rs b/src/bin/flat.rs
index 404b455..14c26e7 100644
--- a/src/bin/flat.rs
+++ b/src/bin/flat.rs
@@ -39,7 +39,14 @@ pub fn main() {
 				.enumerate()
 				.map(|(k, y)| Object {
 					id: k as i32,
-					loc: Location { pos: vec2(0.0, y * tube.external_halflength), rot: Mat2::IDENTITY },
+					loc: {
+						let pos = vec2(0.0, y * tube.external_halflength);
+						let adj = tube.sqrt_at(pos).inverse().into();
+						Location {
+							pos,
+							rot: adj,
+						}
+					},
 					r: 20.0,
 				})
 				.collect();
@@ -68,13 +75,13 @@ pub fn main() {
 				gc.stroke_color(Color::Rgba(0.0, 0.0, 0.0, 0.5));
 				draw_loop(gc, itertools_num::linspace(0.0, 2.0 * PI, 32).skip(1).map(|φ| {
 					let dir = Vec2::from_angle(φ) * obj.r;
-					let dir = space.flat_to_global(pos) * dir;
+					let dir = obj.loc.rot * dir;
 					pos + dir
 				}));
 				gc.stroke_color(Color::Rgba(0.0, 0.5, 1.0, 0.5));
 				draw_loop(gc, itertools_num::linspace(0.0, 2.0 * PI, 32).skip(1).map(|φ| {
 					let dir = Vec2::from_angle(φ) * obj.r;
-					let dir = space.flat_to_global(pos) * dir;
+					let dir = obj.loc.rot * dir;
 					space.trace_step(Ray { pos, dir }).pos
 				}));
 				gc.stroke_color(Color::Rgba(0.5, 0.0, 1.0, 1.0));
@@ -82,7 +89,7 @@ pub fn main() {
 					let n = obj.r.floor();
 					let d = obj.r / n;
 					let dir = Vec2::from_angle(φ);
-					let dir = space.flat_to_global(pos) * dir * d;
+					let dir = obj.loc.rot * dir * d;
 					space.trace_iter(Ray { pos, dir }).nth(n as usize).unwrap().pos
 				}));
 			}