refactor(specctra-core/math/Circle): factor out (angle -> position) routine

crates/specctra-core/src/math.rs

@@ -14,6 +14,19 @@ pub struct PointWithRotation {
     pub rot: f64,
 }
 
+impl Circle {
+    /// Calculate the point that lies on the circle at angle `phi`,
+    /// relative to coordinate axes.
+    ///
+    /// `phi` is the angle given in radians starting at `(r, 0)`.
+    pub fn position_at_angle(&self, phi: f64) -> Point {
+        geo::point! {
+            x: self.pos.0.x + self.r * phi.cos(),
+            y: self.pos.0.y + self.r * phi.sin()
+        }
+    }
+}
+
 impl Sub for Circle {
     type Output = Self;
 

crates/specctra-core/src/structure.rs

@@ -392,6 +392,23 @@ pub struct Point {
     pub y: f64,
 }
 
+impl From<geo::Point> for Point {
+    #[inline(always)]
+    fn from(z: geo::Point) -> Self {
+        Point { x: z.0.x, y: z.0.y }
+    }
+}
+
+impl From<Point> for geo::Point {
+    #[inline(always)]
+    fn from(z: Point) -> Self {
+        geo::point! {
+            x: z.x,
+            y: z.y
+        }
+    }
+}
+
 // Custom impl for the case described above
 impl<R: std::io::BufRead> ReadDsn<R> for Vec<Point> {
     fn read_dsn(tokenizer: &mut ListTokenizer<R>) -> Result<Self, ParseErrorContext> {

crates/topola-egui/src/painter.rs

@@ -42,13 +42,14 @@ impl<'a> Painter<'a> {
                 let angle_from = bend.start_angle();
                 let angle_step = bend.spanned_angle() / 100.0;
 
-                let mut points: Vec<egui::Pos2> = vec![];
-
-                for i in 0..=100 {
-                    let x = circle.pos.x() + circle.r * (angle_from + i as f64 * angle_step).cos();
-                    let y = circle.pos.y() + circle.r * (angle_from + i as f64 * angle_step).sin();
-                    points.push(self.transform.mul_pos([x as f32, -y as f32].into()));
-                }
+                let points = (0..=100)
+                    .into_iter()
+                    .map(|i| circle.position_at_angle(angle_from + i as f64 * angle_step))
+                    .map(|point| {
+                        self.transform
+                            .mul_pos([point.0.x as f32, -point.0.y as f32].into())
+                    })
+                    .collect();
 
                 egui::Shape::line(
                     points,

src/specctra/design.rs

@@ -101,13 +101,12 @@ impl SpecctraDesign {
 
                         (0..=segment_count)
                             .into_iter()
-                            .map(|i| angle_from + i as f64 * angle_step)
-                            .map(|phi| {
-                                let x = circle.pos.x() + circle.r * phi.cos();
-                                let y = circle.pos.y() + circle.r * phi.sin();
-                                structure::Point { x, y }
+                            .map(|i| {
+                                circle
+                                    .position_at_angle(angle_from + i as f64 * angle_step)
+                                    .into()
                             })
-                            .collect()
+                            .collect::<Vec<structure::Point>>()
                     }
 
                     // Intentionally skipped for now.