PMREMGenerator: Fix usage in XR. (#27924)

src/extras/PMREMGenerator.js

@@ -40,6 +40,7 @@ const _clearColor = /*@__PURE__*/ new Color();
 let _oldTarget = null;
 let _oldActiveCubeFace = 0;
 let _oldActiveMipmapLevel = 0;
+let _oldXrEnabled = false;
 
 // Golden Ratio
 const PHI = ( 1 + Math.sqrt( 5 ) ) / 2;
@@ -107,6 +108,9 @@ class PMREMGenerator {
 		_oldTarget = this._renderer.getRenderTarget();
 		_oldActiveCubeFace = this._renderer.getActiveCubeFace();
 		_oldActiveMipmapLevel = this._renderer.getActiveMipmapLevel();
+		_oldXrEnabled = this._renderer.xr.enabled;
+
+		this._renderer.xr.enabled = false;
 
 		this._setSize( 256 );
 
@@ -222,6 +226,8 @@ class PMREMGenerator {
 	_cleanup( outputTarget ) {
 
 		this._renderer.setRenderTarget( _oldTarget, _oldActiveCubeFace, _oldActiveMipmapLevel );
+		this._renderer.xr.enabled = _oldXrEnabled;
+
 		outputTarget.scissorTest = false;
 		_setViewport( outputTarget, 0, 0, outputTarget.width, outputTarget.height );
 
@@ -242,6 +248,9 @@ class PMREMGenerator {
 		_oldTarget = this._renderer.getRenderTarget();
 		_oldActiveCubeFace = this._renderer.getActiveCubeFace();
 		_oldActiveMipmapLevel = this._renderer.getActiveMipmapLevel();
+		_oldXrEnabled = this._renderer.xr.enabled;
+
+		this._renderer.xr.enabled = false;
 
 		const cubeUVRenderTarget = renderTarget || this._allocateTargets();
 		this._textureToCubeUV( texture, cubeUVRenderTarget );