From 52baff44c3350fffeaff0dc7dc9ad8682a4addb4 Mon Sep 17 00:00:00 2001
From: numzero <numzer0@yandex.ru>
Date: Thu, 8 Oct 2026 20:03:53 +0300
Subject: [PATCH] unify shaping code

---
 src/main.rs | 90 ++++++++++++++++++++++++++---------------------------
 1 file changed, 44 insertions(+), 46 deletions(-)

diff --git a/src/main.rs b/src/main.rs
index be95e0e..3051836 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -13,26 +13,32 @@ const fn rad(deg: f32) -> f32 {
 const ADDENDUM: f32 = 1.00;
 const DEDENDUM: f32 = 1.25;
 const PRESSURE_ANGLE: f32 = rad(20.0);
-const PITCH: f32 = PI;
 
-fn cutter_y_at_x(x: f32) -> f32 {
-	let x = (x / PITCH).fract_gl() * PITCH;
-	let a = DEDENDUM * vec2(PRESSURE_ANGLE.tan(), 1.0);
-	let d = ADDENDUM * vec2(PRESSURE_ANGLE.tan(), -1.0);
-	let slope = 1.0 / PRESSURE_ANGLE.tan();
+#[derive(Debug, Clone, Copy)]
+struct Profile {
+	addemdum: f32,
+	dedendum: f32,
+	pressure_angle: f32,
+}
+
+fn rack_shape(x: f32, profile: &Profile) -> f32 {
+	let x = (x / PI).fract_gl() * PI;
+	let a = profile.addemdum * vec2(profile.pressure_angle.tan(), 1.0);
+	let d = profile.dedendum * vec2(profile.pressure_angle.tan(), -1.0);
+	let slope = 1.0 / profile.pressure_angle.tan();
 	if x < d.x {
 		return -x * slope;
 	}
-	if x <= 0.5 * PITCH - d.x {
+	if x <= 0.5 * PI - d.x {
 		return d.y;
 	}
-	if x <= 0.5 * PITCH + a.x {
-		return (x - 0.5 * PITCH) * slope;
+	if x <= 0.5 * PI + a.x {
+		return (x - 0.5 * PI) * slope;
 	}
-	if x <= PITCH - a.x {
+	if x <= PI - a.x {
 		return a.y;
 	}
-	return (PITCH - x) * slope;
+	return (PI - x) * slope;
 }
 
 const FPS: f32 = 60.0;
@@ -52,6 +58,18 @@ fn main() {
 		let n_teeth = 36;
 		let n_teeth_sample = n_teeth;
 		let r_pitch = 0.5 * n_teeth as f32;
+
+		let gear_profile = Profile {
+			addemdum: ADDENDUM,
+			dedendum: DEDENDUM,
+			pressure_angle: PRESSURE_ANGLE,
+		};
+		let cutter_profile = Profile {
+			addemdum: gear_profile.dedendum,
+			dedendum: gear_profile.addemdum,
+			pressure_angle: gear_profile.pressure_angle,
+		};
+
 		let n_points_per_tooth = 100;
 		let n_points = n_points_per_tooth * n_teeth_sample;
 		let mut shape = vec![r_pitch + ADDENDUM; n_points];
@@ -77,6 +95,9 @@ fn main() {
 				let gear_offset = t * TPS - (n_teeth_sample as f32 + 5.0);
 				let rack_offset = (t * TPS).fract_gl();
 
+				let rack_y_at_x = |x, profile| rack_shape(x - rack_offset * PI, profile);
+				let cutter_y_at_x = |x| rack_y_at_x(x, &cutter_profile);
+
 				let kr_to_xy = |k, r: f32| {
 					let u = k as f32 / n_points_per_tooth as f32;
 					let angle = 2.0 * PI * (gear_offset + u) / n_teeth as f32;
@@ -87,7 +108,7 @@ fn main() {
 				for (k, r) in shape.iter_mut().enumerate() {
 					loop {
 						let xy = kr_to_xy(k, *r);
-						let cut_y = cutter_y_at_x(xy.x - rack_offset * PITCH);
+						let cut_y = cutter_y_at_x(xy.x);
 						if cut_y < xy.y {
 							break;
 						}
@@ -95,50 +116,27 @@ fn main() {
 					}
 				}
 
-				#[cfg(false)]
-				{
-					line(
-						gc,
-						shape.iter().enumerate().map(|(k, r)| {
-							let xy = kr_to_xy(k, *r);
-							let cut_y = cutter_y_at_x(xy.x - rack_offset * PITCH);
-							vec2(xy.x, cut_y)
-						}),
-					);
-					gc.stroke_color(Rgba(1.0, 1.0, 0.1, 0.4));
-					gc.stroke();
-				}
-
 				line(gc, shape.iter().enumerate().map(|(k, r)| kr_to_xy(k, *r)));
 				gc.close_path();
 				gc.stroke_color(Rgba(0.1, 0.6, 1.0, 0.4));
 				gc.stroke();
 
-				let mut pts = Vec::new();
+				let mut pts_rack = Vec::new();
+				let mut pts_cutter = Vec::new();
 				for tooth in -n_rack_teeth..=n_rack_teeth {
-					let x = (tooth as f32 + rack_offset) * PITCH;
-					let a = DEDENDUM * vec2(PRESSURE_ANGLE.tan(), 1.0);
-					let d = ADDENDUM * vec2(PRESSURE_ANGLE.tan(), -1.0);
-					pts.push(vec2(x - 0.5 * PITCH - d.x, d.y));
-					pts.push(vec2(x - 0.5 * PITCH + a.x, a.y));
-					pts.push(vec2(x - a.x, a.y));
-					pts.push(vec2(x + d.x, d.y));
+					for k in 0..n_points_per_tooth {
+						let x = (tooth as f32 + k as f32 / n_points_per_tooth as f32 + rack_offset)
+							* PI;
+						pts_rack.push(vec2(x, rack_y_at_x(x, &gear_profile)));
+						pts_cutter.push(vec2(x, cutter_y_at_x(x)));
+					}
 				}
-				line(gc, pts);
+
+				line(gc, pts_cutter);
 				gc.stroke_color(Rgba(1.0, 0.1, 0.1, 0.4));
 				gc.stroke();
 
-				let mut pts = Vec::new();
-				for tooth in -n_rack_teeth..=n_rack_teeth {
-					let x = (tooth as f32 + rack_offset) * PITCH;
-					let a = ADDENDUM * vec2(PRESSURE_ANGLE.tan(), 1.0);
-					let d = DEDENDUM * vec2(PRESSURE_ANGLE.tan(), -1.0);
-					pts.push(vec2(x - 0.5 * PITCH - d.x, d.y));
-					pts.push(vec2(x - 0.5 * PITCH + a.x, a.y));
-					pts.push(vec2(x - a.x, a.y));
-					pts.push(vec2(x + d.x, d.y));
-				}
-				line(gc, pts);
+				line(gc, pts_rack);
 				gc.stroke_color(Rgba(0.1, 1.0, 0.1, 0.4));
 				gc.stroke();
 			});