PointLightShadow: Use own private objects.

Author: mrdoob

src/lights/PointLightShadow.js

@@ -1,9 +1,14 @@
 import { LightShadow } from './LightShadow.js';
 import { PerspectiveCamera } from '../cameras/PerspectiveCamera.js';
+import { Matrix4 } from '../math/Matrix4.js';
 import { Vector2 } from '../math/Vector2.js';
 import { Vector3 } from '../math/Vector3.js';
 import { Vector4 } from '../math/Vector4.js';
 
+const _projScreenMatrix = /*@__PURE__*/ new Matrix4();
+const _lightPositionWorld = /*@__PURE__*/ new Vector3();
+const _lookTarget = /*@__PURE__*/ new Vector3();
+
 class PointLightShadow extends LightShadow {
 
 	constructor() {
@@ -59,24 +64,21 @@ class PointLightShadow extends LightShadow {
 	updateMatrices( light, viewportIndex = 0 ) {
 
 		const camera = this.camera;
-		const	shadowMatrix = this.matrix;
-		const	lightPositionWorld = this._lightPositionWorld;
-		const	lookTarget = this._lookTarget;
-		const	projScreenMatrix = this._projScreenMatrix;
+		const shadowMatrix = this.matrix;
 
-		lightPositionWorld.setFromMatrixPosition( light.matrixWorld );
-		camera.position.copy( lightPositionWorld );
+		_lightPositionWorld.setFromMatrixPosition( light.matrixWorld );
+		camera.position.copy( _lightPositionWorld );
 
-		lookTarget.copy( camera.position );
-		lookTarget.add( this._cubeDirections[ viewportIndex ] );
+		_lookTarget.copy( camera.position );
+		_lookTarget.add( this._cubeDirections[ viewportIndex ] );
 		camera.up.copy( this._cubeUps[ viewportIndex ] );
-		camera.lookAt( lookTarget );
+		camera.lookAt( _lookTarget );
 		camera.updateMatrixWorld();
 
-		shadowMatrix.makeTranslation( - lightPositionWorld.x, - lightPositionWorld.y, - lightPositionWorld.z );
+		shadowMatrix.makeTranslation( - _lightPositionWorld.x, - _lightPositionWorld.y, - _lightPositionWorld.z );
 
-		projScreenMatrix.multiplyMatrices( camera.projectionMatrix, camera.matrixWorldInverse );
-		this._frustum.setFromProjectionMatrix( projScreenMatrix );
+		_projScreenMatrix.multiplyMatrices( camera.projectionMatrix, camera.matrixWorldInverse );
+		this._frustum.setFromProjectionMatrix( _projScreenMatrix );
 
 	}