Fix side orientation based flipping logic

serializers/src/glTF/2.0/glTFExporter.ts

@@ -1272,8 +1272,8 @@ export class _Exporter {
                         let sideOrientation = bufferMesh.overrideMaterialSideOrientation !== null ? bufferMesh.overrideMaterialSideOrientation : babylonMaterial.sideOrientation;
 
                         // Only reverse the winding if we have a clockwise winding
-                        if (sideOrientation == Material.ClockWiseSideOrientation
-                            || (sideOrientation == Material.ClockWiseSideOrientation && convertToRightHandedSystem && bufferMesh.overrideMaterialSideOrientation == bufferMesh.material?.sideOrientation)) {
+                        if ((sideOrientation == Material.ClockWiseSideOrientation && this._babylonScene.useRightHandedSystem)
+                            || (sideOrientation == Material.ClockWiseSideOrientation && convertToRightHandedSystem && bufferMesh.overrideMaterialSideOrientation !== bufferMesh.material?.sideOrientation)) {
                             let byteOffset = indexBufferViewIndex != null ? this._bufferViews[indexBufferViewIndex].byteOffset : null;
                             if (byteOffset == null) { byteOffset = 0; }
                             let babylonIndices: Nullable<IndicesArray> = null;