TIGSource Forums

Hello,
I'm drawing falling leaves in the background of my game.
Their position is set to random x and random y of the screen size.
There's scrolling in my game and it's done using variables sx and sy.
If max x can be 320 and max y can be 240 for the leaves how can I make it that the leaves will scroll along with the screen?
If I simply substract the scrolling position they stay behind and I tried some % (for non C/C++ programmers- it's division remainder) operations on the leaves positions but with no good results. (Like: (x-sx) % 320)
That's a very simple mathematical problem but I somehow cannot think of a solution  :-[ :facepalm:

Thanks in advance for help!

[edit]
Second thing and a similar problem.
I want to draw a tiled background and I also want it relative to screen scrolling. How do I determine the x and y of the tiles and how many of them I have to draw?

leafX = random(0, 640);
leafY = random(0, 480);
leafX -= viewX;
leafY -= viewY;
while (leafX < 0) leafX += 640;
while (leafY < 0) leafX += 480;

I guess you can do it smarter then this, but this works ;-)

Thanks! I haven't thought of that. That actually solves both of my problems.  ;)