as 中常用的一些公式

基本三角函数的计算：
角的正弦值 = 对边 / 斜边
角的余弦值 = 邻边 / 斜边
角的正切值 = 对边 / 邻边

角度制与弧度制的相互转换：
弧度 = 角度 * Math.PI / 180
角度 = 弧度 * 180 / Math.PI

计算两点间距离：
dx = x2 – x1;
dy = y2 – y1;
dist = Math.sqrt(dx*dx + dy*dy);

缓动公式:
sprite.x += (targetX - sprite.x) * easing;//easing为缓动系数变量
sprite.y += (targetY - sprite.y) * easing;

弹性公式:
vx += (targetX - sprite.x) * spring;//spring为弹性系数
vy += (targetY - sprite.y) * spring;
sprite.x += (vx *= friction);//friction为摩擦力
sprite.y += (vy *= friction);

偏移弹性公式:
var dx:Number = sprite.x - fixedX;
var dy:Number = sprite.y - fixedY;
var angle:Number = Math.atan2(dy, dx);
var targetX:Number = fixedX + Math.cos(angle) * springLength;
var targetY:Number = fixedX + Math.sin(angle) * springLength;

向鼠标旋转(或向某点旋转)
dx = mouseX - sprite.x;
dy = mouseY - sprite.y;
sprite.rotation = Math.atan2(dy, dx) * 180 / Math.PI;

波形运动:
public function onEnterFrame1(event:Event):void {
ball.y=centerScale+Math.sin(angle)*range;
angle+=speed;
}

心跳:
public function onEnterFrame1(event:Event):void {
ball.scaleX=centerScale+Math.sin(angle)*range;
ball.scaleY=centerScale+Math.sin(angle)*range;
angle+=speed;
}

圆心旋转:
public function onEnterFrame(event:Event):void {
ball.x=centerX+Math.cos(angle)*radius;
ball.y=centerY+Math.sin(angle)*radius;
angle+=speed;
}

椭圆旋转:
public function onEnterFrame(event:Event):void {
ball.x=centerX+Math.cos(angle)*radiusX;
ball.y=centerY+Math.sin(angle)*radiusY;
angle+=speed;
}