From 8ec7c9161393b3807e4241d5c3f7b1898819a008 Mon Sep 17 00:00:00 2001
From: Stewart Allen <stewart.allen@gmail.com>
Date: Thu, 14 Jan 2021 18:38:53 -0500
Subject: [PATCH] fix mirror normals bug

---
 notes.md           |  1 -
 src/kiri/widget.js | 15 ++++-----------
 2 files changed, 4 insertions(+), 12 deletions(-)

diff --git a/notes.md b/notes.md
index 804e7576..d668158e 100644
--- a/notes.md
+++ b/notes.md
@@ -3,7 +3,6 @@
 ## `C` cosmetic, `F` functional, `P` performance, `B` bug fix
 
 * `B` normals possibly inverted on faces in 2D to 3D conversion
-* `B` some normals inverted on mirrored parts
 * `B` normalize left, bottom, right pop menu time/click and value persistence
 * `B` origin bug (Onshape?) when switching modes in 2.5 and 2.6
 
diff --git a/src/kiri/widget.js b/src/kiri/widget.js
index 15ff2b00..ace821a8 100644
--- a/src/kiri/widget.js
+++ b/src/kiri/widget.js
@@ -273,7 +273,6 @@
         // fix invalid normals
         geometry.computeFaceNormals();
         geometry.computeVertexNormals();
-        // to fix mirroring of normals not working as expected
         mesh.material.side = THREE.DoubleSide;
         mesh.castShadow = true;
         mesh.receiveShadow = true;
@@ -512,18 +511,12 @@
     PRO._mirror = function() {
         this.setWireframe(false);
         this.clearSlices();
-        let i,
-            o = this.track,
-            geo = this.mesh.geometry,
-            at = geo.attributes,
-            pa = at.position.array,
-            nm = at.normal.array;
-        for (i = 0 ; i < pa.length; i += 3) {
-            pa[i] = -pa[i];
-            nm[i] = -nm[i];
-        }
+        this.mesh.applyMatrix4(new THREE.Matrix4().makeScale(-1, 1, 1));
+        let geo = this.mesh.geometry,
+            o = this.track;
         geo.computeFaceNormals();
         geo.computeVertexNormals();
+        this.mesh.position.x = -this.mesh.position.x;
         o.mirror = !o.mirror;
         this.modified = true;
     };