improved slider point interpolation

src/curve.rs

@@ -5,7 +5,8 @@
 
 use crate::{math_util, parse::Pos2};
 
-const SLIDER_QUALITY: f32 = 50.0;
+const BEZIER_TOLERANCE: f32 = 0.25;
+const CATMULL_DETAIL: f32 = 50.0;
 
 pub(crate) enum Points {
     Single(Pos2),
@@ -57,7 +58,7 @@ impl Curve {
     }
 
     fn _bezier(result: &mut Vec<Pos2>, points: &[Pos2]) {
-        let step = (0.25 / SLIDER_QUALITY / points.len() as f32).max(0.01);
+        let step = (BEZIER_TOLERANCE / points.len() as f32).max(0.01);
         let mut i = 0.0;
         let n = points.len() as i32 - 1;
 
@@ -81,7 +82,7 @@ impl Curve {
         let order = points.len();
 
         let mut resulting_points =
-            Vec::with_capacity(((order - 1) as f32 * SLIDER_QUALITY * 2.0) as usize);
+            Vec::with_capacity(((order - 1) as f32 * CATMULL_DETAIL * 2.0) as usize);
 
         for i in 0..order - 1 {
             let v1 = points[i.saturating_sub(1)];
@@ -101,14 +102,14 @@ impl Curve {
 
             let mut c = 0.0;
 
-            while c < SLIDER_QUALITY {
-                resulting_points.push(Self::catmull_point(v1, v2, v3, v4, c / SLIDER_QUALITY));
+            while c < CATMULL_DETAIL {
+                resulting_points.push(Self::catmull_point(v1, v2, v3, v4, c / CATMULL_DETAIL));
                 resulting_points.push(Self::catmull_point(
                     v1,
                     v2,
                     v3,
                     v4,
-                    (c + 1.0) / SLIDER_QUALITY,
+                    (c + 1.0) / CATMULL_DETAIL,
                 ));
 
                 c += 1.0;

src/math_util.rs

@@ -41,11 +41,6 @@ pub(crate) fn point_on_line(p1: Pos2, p2: Pos2, len: f32) -> Pos2 {
     (p1 * n + p2 * len) / full_len
 }
 
-#[inline]
-pub(crate) fn angle_from_points(p0: Pos2, p1: Pos2) -> f32 {
-    (p1.y - p0.y).atan2(p1.x - p0.x)
-}
-
 #[inline]
 pub(crate) fn distance_from_points(arr: &[Pos2]) -> f32 {
     arr.iter()
@@ -55,14 +50,6 @@ pub(crate) fn distance_from_points(arr: &[Pos2]) -> f32 {
         .sum()
 }
 
-#[inline]
-pub(crate) fn cart_from_pol(r: f32, t: f32) -> Pos2 {
-    Pos2 {
-        x: r * t.cos(),
-        y: r * t.sin(),
-    }
-}
-
 pub(crate) fn point_at_distance(array: &[Pos2], distance: f32) -> Pos2 {
     if array.len() < 2 {
         return Pos2 { x: 0.0, y: 0.0 };
@@ -88,14 +75,12 @@ pub(crate) fn point_at_distance(array: &[Pos2], distance: f32) -> Pos2 {
     }
 
     current_distance -= new_distance;
+    let init_dist = distance - current_distance;
 
-    if (distance - current_distance).abs() <= f32::EPSILON {
+    if init_dist.abs() <= f32::EPSILON {
         array[i]
     } else {
-        let angle = angle_from_points(array[i], array[i + 1]);
-        let cart = cart_from_pol(distance - current_distance, angle);
-
-        array[i] + cart * ((array[i].x <= array[i + 1].x) as i8 * 2 - 1) as f32
+        array[i] + (array[i + 1] - array[i]) * (init_dist / new_distance)
     }
 }