diff --git a/src/bin/flat.rs b/src/bin/flat.rs
index cfada16..214d20a 100644
--- a/src/bin/flat.rs
+++ b/src/bin/flat.rs
@@ -51,7 +51,7 @@ struct Space {
 	rect: Rect,
 }
 
-#[derive(PartialEq, Eq)]
+#[derive(PartialEq, Eq, Debug)]
 enum Subspace {
 	Outer,
 	Boundary,
@@ -101,13 +101,10 @@ fn draw_ray_2(gc: &mut Vec<Draw>, space: &Space, base: Vec2, dir: Vec2) {
 	let dir = space.rect.globalize(base, dir);
 	gc.new_path();
 	gc.move_to(base.x, base.y);
-	let dt = DT;
 	let mut p = base;
 	let mut v = space.rect.normalize_vec_at(base, dir);
 	for _ in 0..10000 {
-		let a: Vec2 = -riemann::contract2(riemann::krist(&space.rect, p), v);
-		v = v + a * dt;
-		p = p + v * dt;
+		Ray { pos: p, dir: v } = space.trace_step(Ray { pos: p, dir: v });
 		gc.line_to(p.x, p.y);
 		if p.abs().cmpgt(Vec2::splat(1000.0)).any() {
 			break;
@@ -125,9 +122,7 @@ fn draw_ray_2(gc: &mut Vec<Draw>, space: &Space, base: Vec2, dir: Vec2) {
 			Inner => {
 				let cell = RectInside { rect: space.rect };
 				let ray = cell.ray_to_local(Ray { pos: p, dir: v });
-				let Some(ray) = cell.to_boundary(ray) else {
-					panic!("Can't get outta here!");
-				};
+				let ray = cell.to_boundary(ray).expect("Can't get outta here!");
 				Ray { pos: p, dir: v } = cell.ray_to_global(ray);
 			}
 			Outer => {
@@ -229,7 +224,7 @@ impl Renderable for Rect {
 	}
 }
 
-#[derive(Debug, PartialEq)]
+#[derive(Copy, Clone, Debug, PartialEq)]
 struct Ray {
 	pos: Vec2,
 	dir: Vec2,