adsk-forge-LevelSectionPanel-step12

onButtonClicked() {
    const upperSelector = document.getElementById( 'adn-upper-lvl-selector' );
    const lowerSelector = document.getElementById( 'adn-lower-lvl-selector' );

    if( !upperSelector || !lowerSelector ) return;

    const upperIdx = upperSelector.selectedIndex;
    const upperCutPlaneParam = this.getCutPlaneParam( upperIdx, 1 );
    const lowerIdx = lowerSelector.selectedIndex;
    const lowerCutPlaneParam = this.getCutPlaneParam( lowerIdx, -1 );
    this.viewer.setCutPlanes( [ upperCutPlaneParam, lowerCutPlaneParam ] );
}