From fd327b731a9ce21154bb7a0385925977e8628d67 Mon Sep 17 00:00:00 2001
From: Blake Roberts <blaker2015@gmail.com>
Date: Thu, 28 Nov 2024 18:29:20 -0700
Subject: [PATCH] [#3284] perf: reduce allocations for GraphicsGroup draw calls
 (#3285)

Closes #3284

## Changes:

- reuse single cumulative bounding box for local bounds calculation of `GraphicsGroup` to reduce per-draw allocations
---
 CHANGELOG.md                         | 1 +
 src/engine/Graphics/GraphicsGroup.ts | 6 +++---
 2 files changed, 4 insertions(+), 3 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index a459901c7..e3e578b3e 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -238,6 +238,7 @@ are doing mtv adjustments during precollision.
   * `EventEmitter`s
   * `GraphicsSystem` entity iteration
   * `PointerSystem` entity iteration
+- Perf improvements to `GraphicsGroup` by reducing per draw allocations in bounds calculations
 
 ### Changed
 
diff --git a/src/engine/Graphics/GraphicsGroup.ts b/src/engine/Graphics/GraphicsGroup.ts
index bc44b119e..430afa8a9 100644
--- a/src/engine/Graphics/GraphicsGroup.ts
+++ b/src/engine/Graphics/GraphicsGroup.ts
@@ -58,16 +58,16 @@ export class GraphicsGroup extends Graphic implements HasTick {
   }
 
   public get localBounds(): BoundingBox {
-    let bb = new BoundingBox();
+    const bb = new BoundingBox();
     for (const member of this.members) {
       if (member instanceof Graphic) {
-        bb = member.localBounds.combine(bb);
+        member.localBounds.combine(bb, bb);
       } else {
         const { graphic, offset: pos, useBounds } = member;
         const shouldUseBounds = useBounds === undefined ? true : useBounds;
         if (graphic) {
           if (shouldUseBounds) {
-            bb = graphic.localBounds.translate(pos).combine(bb);
+            graphic.localBounds.translate(pos).combine(bb, bb);
           }
         } else {
           this._logger.warnOnce(`Graphics group member has an null or undefined graphic, member definition: ${JSON.stringify(member)}.`);