Logic Error in Player Controls in Greenfoot

Question

Recently, I've been using Greenfoot, and I wanted to make a simple top-down/bullet-hell shooter. Everything was going smoothly until I tried some of the movement. It's simple enough with good old "arrow keys to move, space to shoot", but the problems show up when I try to move diagonally up-left or down-right and shoot at the same time. I can only do one at a time. I noticed that the directions are related by their location in the else-if calls, but that got me no where. I've also tried moving the code around, replacing the fire() call in act; with the if check entirely, but nothing has changed it.

    import greenfoot.*;

    /**
     * Write a description of class PlayerShip here.
     * 
     * @author (your name) 
     * @version (a version number or a date)
     */
    public class PlayerShip extends SmoothMover
    {
        private int stepSize = 4;
        private boolean tiltLeft = false;
        private boolean tiltRight = false;
        private int tiltFrame = 1;
        private int flameFrame = 0;
        private final int COOLDOWN = 20;
        private int armsCool = 0;
        public PlayerShip()
        {
        }
        /**
         * Act - do whatever the PlayerShip wants to do. This method is called whenever
         * the 'Act' or 'Run' button gets pressed in the environment.
         */
        public void act() 
        {
            setImage();
            if(Greenfoot.isKeyDown("left") && Greenfoot.isKeyDown("right"))
            {
                tiltFrame = 1;
            }
            move();
            fire();
            armsCool ++;
        }

        public void setImage()
        {
            if(Greenfoot.isKeyDown("up"))
            {
                setLocation(getX(), getY() - stepSize - 2);
            }
            else if(Greenfoot.isKeyDown("down"))
            {
                setLocation(getX(), getY() + stepSize + 2);
            }
            if (Greenfoot.isKeyDown("left")) { 
                setLocation(getX() - stepSize, getY());
                tiltLeft = true;
                if(tiltFrame == 1)
                {
                    setImage("LeftTilt1.png");
                    tiltFrame ++;
                }
                else if(tiltFrame == 2)
                {
                    setImage("LeftTilt2.png");
                    tiltFrame++;
                }
                else if(tiltFrame == 3)
                {
                    setImage("LeftTilt3.png");
                    tiltFrame++;
                }
                else
                {
                    if(flameFrame == 1)
                    {
                        setImage("LeftTilt.png");
                        flameFrame --;
                    }
                    else
                    {
                        setImage("LeftTiltAlt.png");
                        flameFrame ++;
                    }
                }
            }
            else if (Greenfoot.isKeyDown("right")) { 
                setLocation(getX() + stepSize,getY());
                tiltRight = true;
                if(tiltFrame == 1)
                {
                    setImage("RightTilt1.png");
                    tiltFrame ++;
                }
                else if(tiltFrame == 2)
                {
                    setImage("RightTilt2.png");
                    tiltFrame++;
                }
                else if(tiltFrame == 3)
                {
                    setImage("RightTilt3.png");
                    tiltFrame++;
                }
                else
                {
                    if(flameFrame == 1)
                    {
                        setImage("RightTilt.png");
                        flameFrame --;
                    }
                    else
                    {
                        setImage("RightTiltAlt.png");
                        flameFrame ++;
                    }
                }
            }
            else
            {
                tiltFrame = 1;
                tiltLeft = false;
                tiltRight = false;
                if(flameFrame == 1)
                {
                    setImage("PlayerShip2.png");
                    flameFrame --;
                }
                else
                {
                    setImage("PlayerShip.png");
                    flameFrame ++;
                }
            }
        }

        private void fire()
        {
           if(Greenfoot.isKeyDown("space") && (armsCool >= COOLDOWN))
            {
                getWorld().addObject(new PlayerBasicBullet(new Vector(12, 5), 251), this.getX(), this.getY());
                Battleground.bulletsOnScreen ++;
                armsCool = 0;
            }
        }

}

The move(); method and Vector class are separate and just for smoother movement. I can provide those too, but there shouldn't be anything in there that messes with the controls.

Answer 1

A slightly modified version of the code works fine on my machine. There's two possibilities that I can think of:

1. Your setImage calls (which I commented out, because I don't have those images) could be throwing an exception, in which case the fire() method wouldn't be reached. Seems unlikely, though, as this would happen even without diagonal movement, and you'd see an exception in the terminal. So, much more likely:

2. Your keyboard may not be able to register those particular three-key combinations. Three ways to test this:

   a. Try this keyboard ghosting demo (click the keyboard at the top of the page) and see if it can register all the keys.

   b. load the Asteroids scenario from the book examples and see if you can shoot bullets while accelerating and steering.

   c. You could just change "space" in your code to, say, "x" and see if works with that key.

Otherwise, I'm at a loss, unless there is code elsewhere in the scenario causing a problem.