diff --git a/src/bin/flat.rs b/src/bin/flat.rs
index 0659f7f..1d31814 100644
--- a/src/bin/flat.rs
+++ b/src/bin/flat.rs
@@ -83,8 +83,8 @@ impl Space {
 	/// ray задаётся в основной СК.
 	fn trace_step(&self, ray: Ray) -> Ray {
 		let a: Vec2 = -riemann::contract2(riemann::krist(&self.rect, ray.pos), ray.dir);
-		let v = ray.dir + a * DT;
-		let p = ray.pos + v * DT;
+		let v = ray.dir + a;
+		let p = ray.pos + v;
 		Ray { pos: p, dir: v }
 	}
 
@@ -131,7 +131,7 @@ fn draw_ray_2(gc: &mut Vec<Draw>, space: &Space, base: Vec2, dir: Vec2) {
 	gc.new_path();
 	gc.move_to(base.x, base.y);
 	let mut p = base;
-	let mut v = space.rect.normalize_vec_at(base, dir);
+	let mut v = space.rect.normalize_vec_at(base, dir) * DT;
 	for _ in 0..10000 {
 		Ray { pos: p, dir: v } = space.trace_step(Ray { pos: p, dir: v });
 		gc.line_to(p.x, p.y);
@@ -157,7 +157,7 @@ fn draw_ray_2(gc: &mut Vec<Draw>, space: &Space, base: Vec2, dir: Vec2) {
 			Outer => {
 				let cell = basic_shapes::Rect { size: vec2(space.rect.outer_radius, space.rect.external_halflength) };
 				let Some(dist) = cell.trace_into(Ray { pos: p, dir: v }) else {
-					p += v * 1000.0;
+					p += v * (1000.0 / DT);
 					gc.line_to(p.x, p.y);
 					gc.stroke();
 					break;
@@ -378,7 +378,7 @@ trait FlatCell: std::fmt::Debug {
 		} else {
 			(bnd.1.y - p.y) / v.y
 		};
-		if t <= 1000.0 {
+		if t <= 100000.0 {
 			Some(Ray { pos: sgn * (p + v * t), dir: sgn * v })
 		} else {
 			None