HTML5-飞机加速减速游戏

代码片段：

Insane.kolizeSlowery = function(a, b) {
var distance_squared = (((a.x - b.x) * (a.x - b.x)) + ((a.y - b.y) * (a.y - b.y)));
//console.log(a.y);
//console.log(b.y);
distance_squared = Math.sqrt(distance_squared);
//console.log("dist: " + distance_squared + " rad: " + (b.km*5));
if (distance_squared < (b.km*4)) {
return true;
}
else {
return false;
}
}