if (balls[i].x - balls[i].radius<=0) {
balls[i].vx = -balls[i].vx;
balls[i].x = balls[i].radius;
}
if (balls[i].x + balls[i].radius >= canvasWidth) {
balls[i].vx = -alls[i].vx;
balls[i].x = canvasWidth-balls[i].radius;
}
if (balls[i].y - balls[i].radius <= 0) {
balls[i].vy = -balls[i].vy;
balls[i].y = balls[i].radius;
}
if (balls[i].y + alls[i].radius >= canvasHeight) {
balls[i].vy = -s[i].vy;
balls[i].y = canvasHeight-balls[i].radius;
}
这是update函数部分
canvas中间的标签是当canvas无法正确显示时显示的内容