ball._x+=xspeed;
ball._y+=yspeed;
if (ball.hitTest(paddle)) {
 yspeed*=-1;
 yspeed+=-.5;
 xspeed=(ball._x-paddle._x)/2;
}
if (ball.hitTest(wall1)) {
 xspeed*=-1;
}
if (ball.hitTest(wall2)) {
 xspeed*=-1;
}
if (ball.hitTest(top)) {
 yspeed*=-1;
}
if (ball._y>=450) {
 ball._x=150;
 ball._y=125;
 xspeed=10;
 yspeed=10;
}