HTML and CSS Reference
In-Depth Information
Chapter 6
Remove an out-of-bounds object
if (object.x - object.width / 2 > right ||
object.x + object.width / 2 < left ||
object.y - object.height / 2 > bottom ||
object.y + object.height / 2 < top) {
//code to remove object
}
Regenerate an out-of-bounds object
if (object.x - object.width / 2 > right ||
object.x + object.width / 2 < left ||
object.y - object.height / 2 > bottom ||
object.y + object.height / 2 < top) {
//reset object position and velocity
}
Screen wrapping for an out-of-bounds object
if (object.x - object.width / 2 > right) {
object.x = left - object.width / 2;
} else if (object.x + object.width / 2 < left) {
object.x = right + object.width / 2;
}
if (object.y - object.height / 2 > bottom) {
object.y = top - object.height / 2;
} else if (object.y + object.height / 2 < top) {
object.y = bottom + object.height / 2;
}
Apply friction (the correct way)
speed = Math.sqrt(vx * vx + vy * vy);
angle = Math.atan2(vy, vx);
if (speed > friction) {
speed -= friction;
} else {
speed = 0;
}
vx = Math.cos(angle) * speed;
vy = Math.sin(angle) * speed;
