I’ve been having problems with undoing custom commands. Hoping that someone can shed some light on how to change these commands so that undoing them works better.

If I have something selected, run this:

    var factory = moi.command.createFactory( 'line' );
    factory.setInput( 0, moi.vectorMath.createPoint( 0, 0, 0 ) );
    factory.setInput( 1, moi.vectorMath.createPoint( 0, 0, 10 ) );
    var lineInList = factory.calculate();
    
    moi.geometryDatabase.deselectAll();
    
    moi.geometryDatabase.addObjects(lineInList);

and then hit Undo, the new line goes away, but the previously selected object stays unselected.

But, if I swap the order of the last two lines:

    var factory = moi.command.createFactory( 'line' );
    factory.setInput( 0, moi.vectorMath.createPoint( 0, 0, 0 ) );
    factory.setInput( 1, moi.vectorMath.createPoint( 0, 0, 10 ) );
    var lineInList = factory.calculate();
    
    moi.geometryDatabase.addObjects(lineInList);
    
    moi.geometryDatabase.deselectAll();

Then hitting Undo once causes the previously selected object to become selected again, while hitting Undo a second time makes the line finally go away.

How should I get a command to act like a single thing (1 undo unit generated ?) so that hitting Undo once brings back the scene exactly as it was before running the command?