Question

so I have a ball (sprite subclass) that can be dragged around the screen and updates it body to tell the world its position.

The problem is, when I apply a force to the ball while the ball is being touched (thus being controlled by a finger), I have two pieces of code fighting against each other to update the sprite’s visual position.

The world stepper is trying to follow through the physics and update the ball’s position. The touch methods however are also trying to update the ball’s body and graphic position. Ideally, when touched I would like to kill off any physics affecting the ball.

So what exactly should I be trying to do to consolidate this? This is also creating issues for collisions and filtering. Any help appreciated. Thanks

Answer 1

Do you want the ball to have an accurate physics simulation? If not, you could always use the SetTransform method of the b2body class like this.

    CGPoint ballLocation = ;//use the touched location for this
    b2Vec2 vecBallLocation = b2Vec2(ballLocation.x / 32, ballLocation.y / 32);//calculate this on your own
    b2Body * ballBody = ;//replace this variable with your ball's b2Body;
    ballBody->SetTransform(vecBallLocation, ballBody->GetAngle());

Do not set the ball sprite’s position manually. Leave this up to the physics simulation. Your code will get really messy over time if you have to keep track of what sprites you set the position of manually and which ones use the physics simulation to update their positions. This way is also much easier.