Using Vectors for 2d animation [closed]

Question

I've decided that it's best to start using vectors in my games instead of the
xPos += xSpeed and yPos += ySpeed approach.

I'm posting some of the code from my basic model class which handles movement logic in my game so that someone can tell me if I am using vectors correctly. I have a position, direction, acceleration and velocity vector. Here is some code, I can post more if needed:

model.update() and rotate() function

public function update():void
{
    checkInput();
    pos.addVec(velocity);
    velocity.addVec(accel);
    velocity.multiplyScalar(friction);
    dispatchEvent(new Event(Event.CHANGE));
}

public function rotate(val:Number):void
{
    angle += val;
    direction.x = Math.cos(angle * degreesToRads);
    direction.y = Math.sin(angle * degreesToRads);
    direction.normalize();
}

and the checkInput() function

private function checkKeys():void 
{
    accel.set(0, 0);
    if(keys[Keyboard.LEFT])
    {
        rotate( -5);
    }
    if (keys[Keyboard.RIGHT])
    {
        rotate(5);
    }
    if (keys[Keyboard.UP])
    {
        accel.x = direction.x * 0.8;
        accel.y = direction.y * 0.8;
    }
    if (keys[Keyboard.DOWN])
    {
        accel.x = direction.x * 0.5;
        accel.y = direction.y * 0.5;
    }
}

Hopefully someone can tell me if I'm using vectors correctly by adding acceleration to velocity and to speed and also if I'm doing rotation the correct way or if there is a better way. Or anything anyone can suggest to improve would be great.

Answer 1

There's no "correct" way to do this. Using xPos += xSpeed and yPos += ySpeed is basically the same as pos.addVec(velocity). I suggest you use what you're comfortable with.

If movement behaves as it should, then go ahead. Some minor things you could improve, by looking at your code:

• Events are slow. Don't dispatch them in the update loop... call methods directly or use signals.
• You should calculate movement in a framerate independent fashion, so that your game runs at the same speed on slower computers as well. The way to do this would be to measure the elapsed time since the last frame and use this delta for movement calculation.
• You don't need to normalize your direction after the rotation calculation. It's a unit vector already.