in viewer/legacy/js/TrackballControls.js [349:375]
function keydown( event ) {
if ( _this.enabled === false ) return;
window.removeEventListener( 'keydown', keydown );
_prevState = _state;
if ( _state !== STATE.NONE ) {
return;
} else if ( event.keyCode === _this.keys[ STATE.ROTATE ] && !_this.noRotate ) {
_state = STATE.ROTATE;
} else if ( event.keyCode === _this.keys[ STATE.ZOOM ] && !_this.noZoom ) {
_state = STATE.ZOOM;
} else if ( event.keyCode === _this.keys[ STATE.PAN ] && !_this.noPan ) {
_state = STATE.PAN;
}
}