progress

gpx-rs/src/algorithms/simplify.rs

@@ -0,0 +1,42 @@
+use crate::gpx::TrackPoint;
+
+pub fn ramer_douglas_peucker<F>(n: usize, distance: &F, epsilon: f64) -> Vec<usize>
+where
+    F: Fn(usize, usize, usize) -> f64,
+{
+    if n <= 2 {
+        (0..n).collect()
+    } else {
+        let mut indices = vec![0];
+        ramer_douglas_peucker_helper(0, n - 1, distance, epsilon, &mut indices);
+        indices.push(n - 1);
+        indices
+    }
+}
+
+fn ramer_douglas_peucker_helper<F>(
+    start: usize,
+    end: usize,
+    distance: &F,
+    epsilon: f64,
+    indices: &mut Vec<usize>,
+) where
+    F: Fn(usize, usize, usize) -> f64,
+{
+    let mut idx = 0;
+    let mut max_dist = 0.0;
+
+    for i in (start + 1)..end {
+        let dist = distance(start, end, i);
+        if dist > max_dist {
+            idx = i;
+            max_dist = dist;
+        }
+    }
+
+    if max_dist > epsilon && idx != 0 {
+        ramer_douglas_peucker_helper(start, idx, distance, epsilon, indices);
+        indices.push(idx);
+        ramer_douglas_peucker_helper(idx, end, distance, epsilon, indices);
+    }
+}