Question

I am taking an experimental first shot at writing a simple side-scroller game. I have this code for re-centering the screen if the player moves too far in some direction.

Is there a better way to write it? I feel like I am abusing the language, but it worked out so nicely that I think it might be okay.

public void adjustFrameIfNecessary()
{
    int dx, dy;
    if ((dx = (GAME_WIDTH - GAME_WIDTH / 3) - player.x) < 0 || (dx = GAME_WIDTH / 3 - player.x) > 0 || (dx = 0) == 0);
    if ((dy = (GAME_HEIGHT - GAME_HEIGHT / 3) - player.y) < 0 || (dy = GAME_HEIGHT / 3 - player.y) > 0 || (dy = 0) == 0);

    if(dx != 0 || dy != 0)
    {
        for (Drawable shiftMe : drawables)
        {
            shiftMe.unconditionalShift(dx, dy);
        }
    }

}

EDIT

With regards to everyone’s input, in an attempt to make it more readable, I have changed it to this

public void adjustFrameIfNecessary()
{
    int dx, dy;

    assignX:
    {
        dx = (GAME_WIDTH - GAME_WIDTH / 3) - player.x;
        if(dx < 0) break assignX;
        dx = GAME_WIDTH / 3 - player.x;
        if(dx > 0) break assignX;
        dx = 0;
    }

    assignY:
    {
        dy = (GAME_HEIGHT - GAME_HEIGHT / 3) - player.y;
        if(dy < 0) break assignY;
        dy = GAME_HEIGHT / 3 - player.y;
        if(dy > 0) break assignY;
        dy = 0;
    }

    if (dx != 0 || dy != 0)
    {
        for (Drawable shiftMe : drawables)
        {
            shiftMe.unconditionalShift(dx, dy);
        }
    }

}

Is this better?

EDIT 2

public void adjustFrameIfNecessary()
{
    int dx = calculateShift(GAME_WIDTH, frameReference.x);
    int dy = calculateShift(GAME_HEIGHT, frameReference.y);

    if (dx != 0 || dy != 0)
    {
        for (Drawable shiftMe : drawables)
        {
            shiftMe.unconditionalShift(dx, dy);
        }
    }
}

I think that it is clear now. Thanks everyone.

Answer 1

Unreadable, but I get your point. One thing, though: why not reuse the same check for both x and y? And by using the ternary operator you get one hack less.

static int toBounds(int max, int curr) {
  int ret;
  return ((ret = (max - max/3) - curr) < 0 || (ret = max/3 - curr) > 0)? ret : 0;
}