From 0d683eb9d2dcf97d48e864230e8fa918d8056911 Mon Sep 17 00:00:00 2001
From: Jono Brandel <developer@jono.fyi>
Date: Fri, 20 Sep 2024 21:28:19 -0700
Subject: [PATCH] Handle negative scale values

---
 src/renderers/webgl.js   | 42 ++++++++++++++++++++++++++--------------
 wiki/changelog/README.md |  1 +
 2 files changed, 29 insertions(+), 14 deletions(-)

diff --git a/src/renderers/webgl.js b/src/renderers/webgl.js
index 389f1d31..56d9ab83 100644
--- a/src/renderers/webgl.js
+++ b/src/renderers/webgl.js
@@ -546,13 +546,16 @@ const webgl = {
         if (!(this._renderer.scale instanceof Vector)) {
           this._renderer.scale = new Vector();
         }
+        let sx, sy;
         if (this._scale instanceof Vector) {
-          this._renderer.scale.x = this._scale.x * parent._renderer.scale.x;
-          this._renderer.scale.y = this._scale.y * parent._renderer.scale.y;
+          sx = this._scale.x * parent._renderer.scale.x;
+          sy = this._scale.y * parent._renderer.scale.y;
         } else {
-          this._renderer.scale.x = this._scale * parent._renderer.scale.x;
-          this._renderer.scale.y = this._scale * parent._renderer.scale.y;
+          sx = this._scale * parent._renderer.scale.x;
+          sy = this._scale * parent._renderer.scale.y;
         }
+        this._renderer.scale.x = sx < 0 ? -sx : sx;
+        this._renderer.scale.y = sy < 0 ? -sy : sy;
 
         if (parentChanged) {
           this._renderer.parent = parent;
@@ -839,13 +842,16 @@ const webgl = {
         if (!(this._renderer.scale instanceof Vector)) {
           this._renderer.scale = new Vector();
         }
+        let sx, sy;
         if (this._scale instanceof Vector) {
-          this._renderer.scale.x = this._scale.x * parent._renderer.scale.x;
-          this._renderer.scale.y = this._scale.y * parent._renderer.scale.y;
+          sx = this._scale.x * parent._renderer.scale.x;
+          sy = this._scale.y * parent._renderer.scale.y;
         } else {
-          this._renderer.scale.x = this._scale * parent._renderer.scale.x;
-          this._renderer.scale.y = this._scale * parent._renderer.scale.y;
+          sx = this._scale * parent._renderer.scale.x;
+          sy = this._scale * parent._renderer.scale.y;
         }
+        this._renderer.scale.x = sx < 0 ? -sx : sx;
+        this._renderer.scale.y = sy < 0 ? -sy : sy;
 
         if (parentChanged) {
           this._renderer.parent = parent;
@@ -1270,13 +1276,16 @@ const webgl = {
         if (!(this._renderer.scale instanceof Vector)) {
           this._renderer.scale = new Vector();
         }
+        let sx, sy;
         if (this._scale instanceof Vector) {
-          this._renderer.scale.x = this._scale.x * parent._renderer.scale.x;
-          this._renderer.scale.y = this._scale.y * parent._renderer.scale.y;
+          sx = this._scale.x * parent._renderer.scale.x;
+          sy = this._scale.y * parent._renderer.scale.y;
         } else {
-          this._renderer.scale.x = this._scale * parent._renderer.scale.x;
-          this._renderer.scale.y = this._scale * parent._renderer.scale.y;
+          sx = this._scale * parent._renderer.scale.x;
+          sy = this._scale * parent._renderer.scale.y;
         }
+        this._renderer.scale.x = sx < 0 ? -sx : sx;
+        this._renderer.scale.y = sy < 0 ? -sy : sy;
 
         if (parentChanged) {
           this._renderer.parent = parent;
@@ -1516,11 +1525,16 @@ const webgl = {
           this._renderer.scale = new Vector();
         }
 
+        let sx, sy;
         if (this._scale instanceof Vector) {
-          this._renderer.scale.copy(this._scale);
+          sx = this._scale.x;
+          sy = this._scale.y;
         } else {
-          this._renderer.scale.set(this._scale, this._scale);
+          sx = this._scale;
+          sy = this._scale;
         }
+        this._renderer.scale.x = sx < 0 ? -sx : sx;
+        this._renderer.scale.y = sy < 0 ? -sy : sy;
       }
 
       return this.flagReset();
diff --git a/wiki/changelog/README.md b/wiki/changelog/README.md
index ad786ab2..19cb5565 100644
--- a/wiki/changelog/README.md
+++ b/wiki/changelog/README.md
@@ -13,6 +13,7 @@ All notable changes to this project will be documented in this file. The format
 
 ## Nightly
 
++ `Two.WebGLRenderer` correctly handles negative scale values
 + `Two.Path.noStroke`, `Two.Text.noStroke`, and derivative methods now include setting both the stroke color to `"none"` and the line width to 0
 + Fixed `Two.Arc` flag behavior for `Two.Arc.width` and `Two.Arc.height` properties