Vector re = position;
if (position.x < halfScreenWidth) {
re = re.modifyX(halfScreenWidth);
}
if (position.y < halfScreenHeight) {
re = re.modifyY(halfScreenHeight);
}
if (position.x > world.width - halfScreenWidth) {
re = re.modifyX(world.width - halfScreenWidth);
}
if (position.y > world.height - halfScreenHeight) {