From 05a9bca48544ac430ed2e31b7b4f7dadf097a2f6 Mon Sep 17 00:00:00 2001
From: Stewart Allen <sa@grid.space>
Date: Sat, 21 Jun 2025 22:22:37 -0400
Subject: [PATCH] fix ctrl click to select planar matching lines

---
 src/geo/polygon.js          | 13 +++++++++++++
 src/kiri-mode/cam/client.js |  3 ++-
 2 files changed, 15 insertions(+), 1 deletion(-)

diff --git a/src/geo/polygon.js b/src/geo/polygon.js
index 2bd7580f..5d5fa478 100644
--- a/src/geo/polygon.js
+++ b/src/geo/polygon.js
@@ -1006,6 +1006,19 @@ class Polygon {
         return Math.min(...this.points.map(p => p.z));
     }
 
+    avgZ() {
+        return [...this.points.map(p => p.z)].reduce((a,v) => a+v) / this.points.length;
+    }
+
+    /**
+     * @param {*} z value target
+     * @param {*} epsilon allowed Z variance
+     * @returns {boolean} true if all points Z within epsilon of value
+     */
+    onZ(z, epsilon = 10e-4) {
+        return Math.max(...this.points.map(p => Math.abs(z - p.z))) < epsilon;
+    }
+
     /**
      */
     render(layer, color, recursive, open) {
diff --git a/src/kiri-mode/cam/client.js b/src/kiri-mode/cam/client.js
index 53993015..e2ff19f0 100644
--- a/src/kiri-mode/cam/client.js
+++ b/src/kiri-mode/cam/client.js
@@ -1128,8 +1128,9 @@ CAM.init = function(kiri, api) {
         if (ev.metaKey || ev.ctrlKey) {
             let { selected } = object;
             let { widget, poly } = object.trace;
+            let avgZ = poly.avgZ();
             for (let add of widget.adds) {
-                if (add.trace && add.selected !== selected && add.trace.poly.getZ() === poly.getZ()) {
+                if (add.trace && add.selected !== selected && add.trace.poly.onZ(avgZ)) {
                     func.traceToggle(add);
                 }
             }