一些AS3中常用到的公式小结

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;
}

颜色运算得到透明值:
var t:uint=0×77ff8877
var s:uint=0xff000000
var h:uint=t&s
var m:uint=h>>>24
trace(m)

转换为十进制:
trace(hexvalue);
十进制转换为十六进制:
decimalvalue.tostring(16)

颜色提取:
red = color24 >> 16;
green = color24 >> 8 & 0xff;
blue = color24 & 0xff;
alpha = color32 >> 24;
red = color32 >> 16 & 0xff;
green = color32 >> 8 & 0xff;
blue = color232 & 0xff;

按位计算得到颜色值:
color24 = red << 16 | green << 8 | blue;
color32 = alpha << 24 | red << 16 | green << 8 | blue;

过控制点的曲线:
// xt, yt是你想要让曲线通过的那一点
// x0, y0 和x2, y2 是曲线的终点
//ps.发现很多人转帖都是直接复制粘贴，也不翻译一下
xt * 2 – (x0 + x2) / 2;
y1 = yt * 2 – (y0 + y2) / 2;
moveto(x0, y0);
curveto(x1, y1, x2, y2);