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?