diff --git a/src/bin/flat/main.rs b/src/bin/flat/main.rs
index 30c066c..85ee39c 100644
--- a/src/bin/flat/main.rs
+++ b/src/bin/flat/main.rs
@@ -275,6 +275,20 @@ impl Space {
 				None
 			}).collect()
 	}
+
+	fn line(&self, a: Vec2, b: Vec2, step: f32) -> Vec<Vec2> {
+		match self.which_subspace(a) {
+			Outer => vec![b],
+			Inner => {
+				let cell = RectInside { rect: self.rect };
+				let n = ((b - a).length() / step) as usize + 1;
+				let a = cell.pos_to_local(a);
+				let b = cell.pos_to_local(b);
+				(1..=n).map(|k| cell.pos_to_global(a.lerp(b, k as f32 / n as f32))).collect()
+			}
+			Boundary => panic!("Can't draw a line here!"),
+		}
+	}
 }
 
 fn draw_ray_2(gc: &mut Vec<Draw>, space: &Space, base: Vec2, dir: Vec2) {
@@ -306,6 +320,7 @@ fn draw_ray_2(gc: &mut Vec<Draw>, space: &Space, base: Vec2, dir: Vec2) {
 		for hit in ret.objects {
 			hits.circle(hit.pos.x, hit.pos.y, 1.5);
 		}
+		let a = ray.pos;
 		ray = match ret.end {
 			Some(r) => r,
 			None => {
@@ -314,7 +329,9 @@ fn draw_ray_2(gc: &mut Vec<Draw>, space: &Space, base: Vec2, dir: Vec2) {
 				break;
 			}
 		};
-		gc.line_to(ray.pos.x, ray.pos.y);
+		for p in space.line(a, ray.pos, 10.0) {
+			gc.line_to(p.x, p.y);
+		}
 		gc.stroke();
 		gc.new_dash_pattern();
 		gc.new_path();