XNA: Preventing a method from returning

Question

I want a method in a DrawableGameComponent class to not return until a particular condition is met

Say I have this class (snippet from a DrawableGameComponent class):

public override void Update(GameTime gameTime)
        {
            if (moving && pixFromLastMove <= distanceToMove)
            {
                position += velocity;
                pixFromLastMove += velocity.Length();
            }
            else
            {
                moving = false;
            }
            if (rotating)
            {
                rotation += 0.1f;
                var cRotation = MathHelper.Clamp(rotation, -MathHelper.PiOver2, angleBeforeRotation + degToRotate);
                if (cRotation != rotation)
                {
                    rotation = cRotation;
                    angleBeforeRotation = rotation;
                    rotating = false;
                }
            }
            base.Update(gameTime);
        }

public void Ahead(int pix)
        {
            moving = true;
            distanceToMove = pix;
            pixFromLastMove = 0;
            velocity = new Vector2((float) Math.Cos(rotation), (float) Math.Sin(rotation))*5.0f;

            //DO NOT RETURN UNTIL THIS ROBOT HAS MOVED TO ITS DESTINATION
            }

public void TurnLeft(int deg)
        {
            rotating = true;
            degToRotate = MathHelper.ToRadians(deg);
            angleBeforeRotation = rotation;

            //DO NOT RETURN UNTIL THIS ROBOT HAS BEEN FULLY ROTATED
        }

This class is being drawn (Draw())in the main thread (because this drawablegamecomponent is executing in seperate thread), and also in the main thread I have a list of commands that I want to be executed in order...but currently, since the Ahead method returns just after assigning a value to velocity, the methods will run almost concurrently, which in turn just executes all the animations at the same time.

So what do you think should I do to prevent methods that are commands (Ahead,TurnLeft etc..) from returning before a certain condition is met?

Answer 1

You need to create some kind of state machine for your Update() method. e.g.

public override void Update() { 
    if (movingRobot) {
        OnlyUpdateRobotPosition();
    }
    else {
        DoStuffPerhapsIncludingStartingRobotMove();
    }
}

Or am I missing the question?