CSM: Reuse origin vector. (#32331)

Author: Mugen87

examples/jsm/csm/CSM.js

@@ -13,6 +13,7 @@ import { CSMShader } from './CSMShader.js';
 const _cameraToLightMatrix = new Matrix4();
 const _lightSpaceFrustum = new CSMFrustum( { webGL: true } );
 const _center = new Vector3();
+const _origin = new Vector3();
 const _bbox = new Box3();
 const _uniformArray = [];
 const _logArray = [];
@@ -367,7 +368,7 @@ export class CSM {
 
 		// for each frustum we need to find its min-max box aligned with the light orientation
 		// the position in _lightOrientationMatrix does not matter, as we transform there and back
-		_lightOrientationMatrix.lookAt( new Vector3(), this.lightDirection, _up );
+		_lightOrientationMatrix.lookAt( _origin, this.lightDirection, _up );
 		_lightOrientationMatrixInverse.copy( _lightOrientationMatrix ).invert();
 
 		for ( let i = 0; i < frustums.length; i ++ ) {