actionscript中常用的基本公式(1)

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

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

创建波形：
// assign value to x, y or other property of sprite or movie clip,
// use as drawing coordinates, etc.
public function onEnterFrame(event:Event){
    value = center + Math.sin(angle) * range;
    angle += speed;
}

创建圆形：
// assign position to x and y of sprite or movie clip,
// use as drawing coordinates, etc.
public function onEnterFrame(event:Event){
    xposition = centerX + Math.cos(angle) * radius;
    yposition = centerY + Math.sin(angle) * radius;
    angle += speed;
}

创建椭圆：
// assign position to x and y of sprite or movie clip,
// use as drawing coordinates, etc.
public function onEnterFrame(event:Event){
    xposition = centerX + Math.cos(angle) * radiusX;
    yposition = centerY + Math.sin(angle) * radiusY;
    angle += speed;
}

计算两点间距离：
// points are x1, y1 and x2, y2
// can be sprite / movie clip positions, mouse coordinates, etc.
dx = x2 – x1; dy = y2 – y1;
dist = Math.sqrt(dx*dx + dy*dy);