From 155d01db5b5aba80ec23699ec6a5c4ff23237ebe Mon Sep 17 00:00:00 2001
From: Stewart Allen <sa@grid.space>
Date: Sat, 8 Jan 2022 16:39:28 -0500
Subject: [PATCH] use bounds caching to speed up rotate & scale operations

---
 src/mesh/api.js | 17 ++++++++++++++---
 1 file changed, 14 insertions(+), 3 deletions(-)

diff --git a/src/mesh/api.js b/src/mesh/api.js
index 524a7903..2da7eedf 100644
--- a/src/mesh/api.js
+++ b/src/mesh/api.js
@@ -298,6 +298,7 @@ let api = mesh.api = {
 };
 
 let deferFn = [];
+let boundsCache = {};
 
 let util = mesh.util = {
 
@@ -381,9 +382,19 @@ let util = mesh.util = {
 
         if (geometry) {
             let matrix = object.matrixWorld;
-            let position = geometry.attributes.position.clone();
-            position.applyMatrix4(new THREE.Matrix4().extractRotation(matrix));
-            let bounds = new THREE.Box3().setFromBufferAttribute(position);
+            let bkey = [matrix.elements.map(v => v.round(5))].join(',')
+            let cached = boundsCache[object.id];
+            let bounds;
+            if (!cached || cached.bkey !== bkey) {
+                let position = geometry.attributes.position.clone();
+                position.applyMatrix4(new THREE.Matrix4().extractRotation(matrix));
+                bounds = new THREE.Box3().setFromBufferAttribute(position);
+                cached = boundsCache[object.id] = {
+                    bkey,
+                    bounds
+                };
+            }
+            bounds = cached.bounds.clone();
             let bt = new THREE.Box3().copy(bounds);
             let m4 = new THREE.Matrix4();
             m4.setPosition(new THREE.Vector3().setFromMatrixPosition(object.matrixWorld));