游戏开发中的数学和物理算法

http://www.cnblogs.com/HelloCG/category/172682.html

定义点：

function Point(x,y) {
  this.x = x;
  this.y = y;
}

两点间的距离：

function pointDistance(p1, p2) {
   var dx = p1.x - p2.x;
   var dy = p1.y - p2.y;
   var distance = Math.sqrt(Math.pow(dx, 2) + Math.pow(dy, 2));
   return distance;
 }

定义圆：

function Circle(point, r) {
   this.center = point;
   this.radius = r;
}

圆的碰撞检测：

fuction collisionBetweenCircles(circle1,circle2) {
  var hit;
  var powerOfDistanceOfCenter = Math.pow((circle1.center.x - circle2.center.x), 2) +
        Math.pow((circle1.center.y - circle2.center.y), 2));
  var powerOfDistanceOfRadius = Math.pow(circle1.radius + circle2.radius, 2);
  if (powerOfDistanceOfCenter <= powerOfDistanceOfRadius) {
    hit=true;
  } else {
    hit=false;
  }
  return hit;
}