三角函数的相关算法

1) 向某点旋转：

dx = mouseX - sprite.x;

dy = mouseY - sprite.y;

sprite.rotation = Math.atan2(dy,dx) * 180 / Math.PI;

2) 创建波形：

public function onEnterFrame(event:Event){

value = center + Math.sin(angle) * range;

angle += speed;

}

3) 创建圆形：

public function onEnterFrame(event:Event){

xposition = centerX + Math.cos(angle) * radius;

yposition = centerY + Math.sin(angle) * radius;

angle += speed;

}

4) 创建椭圆：

public function onEnterFrame(event:Event){

xposition = centerX + Math.cos(angle) * radiusX;

yposition = centerY + Math.sin(angle) * radiusY;

angle += speed;

}

5) 计算两点间距离：

dx = x2 - x1;

dy = y2 - y1;

dist = Math.sqrt(dx*dx + dy*dy);