From ad9c8d6d37721efe623bc56a0e2650b2485337f2 Mon Sep 17 00:00:00 2001
From: Ruben van de Ven <git@rubenvandeven.com>
Date: Tue, 8 Jul 2025 10:01:36 +0200
Subject: [PATCH] utils for trap/clipping

---
 src/trap/utils.rs | 52 +++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 52 insertions(+)
 create mode 100644 src/trap/utils.rs

diff --git a/src/trap/utils.rs b/src/trap/utils.rs
new file mode 100644
index 0000000..703857b
--- /dev/null
+++ b/src/trap/utils.rs
@@ -0,0 +1,52 @@
+// GPT generated code is isolated to this file
+use geo::{Coordinate, Line, Point, Polygon, prelude::*};
+
+///////////////////////
+// Clip filter related
+///////////////////////
+
+// find distance of edge do point (used by GUI)
+pub fn point_to_segment_distance_squared(p: [f32; 2], a: [f32; 2], b: [f32; 2]) -> f32 {
+    let ab = [b[0] - a[0], b[1] - a[1]];
+    let ap = [p[0] - a[0], p[1] - a[1]];
+    let ab_len_sq = ab[0] * ab[0] + ab[1] * ab[1];
+    
+    if ab_len_sq == 0.0 {
+        // Edge is a single point
+        return ap[0] * ap[0] + ap[1] * ap[1];
+    }
+    
+    // Project point onto segment, clamped to [0,1]
+    let t = ((ap[0] * ab[0] + ap[1] * ab[1]) / ab_len_sq).clamp(0.0, 1.0);
+    let closest = [a[0] + t * ab[0], a[1] + t * ab[1]];
+    
+    let dx = p[0] - closest[0];
+    let dy = p[1] - closest[1];
+    dx * dx + dy * dy
+}
+
+
+// find distance of edge do point (used by GUI)
+pub fn closest_edge(mask: &[[f32; 2]], target: [f32; 2]) -> Option<usize> {
+    if mask.len() < 2 {
+        return None;
+    }
+
+    let mut min_dist_sq = f32::MAX;
+    let mut closest_edge_index = 0;
+
+    for i in 0..mask.len() {
+        let a = mask[i];
+        let b = mask[(i + 1) % mask.len()];
+        let dist_sq = point_to_segment_distance_squared(target, a, b);
+
+        if dist_sq < min_dist_sq {
+            min_dist_sq = dist_sq;
+            closest_edge_index = i;
+        }
+    }
+
+    Some(closest_edge_index)
+}
+
+