一个随机画圆弧的效果，有几个属性可调整，也不多描述了，
贴一下代码，有兴趣的看一下吧，刚加了下注释...
//******* draw_arc ************************
//******************* 作者：boenlee *****
//舞台元件：
//可视区域元件--mask
//移动按钮--up_btn, down_btn, left_btn, right_btn
//文本框--angle_txt, time_txt, r_txt, thickness_txt
//复选按钮--trace_check, leaf_check
//重画按钮--redraw_btn
//库链接元件：
//叶子--leaf
//***************************************************
//画小于等于45度的圆弧，任意角度开始
//mc：目标mc名称
//ox：原点x位置
//oy：原点y位置
//r：半径
//origin_angle：起始角度
//angle：弧的角度，正数顺时针画弧，负数逆时针画弧
//thickness：线的粗细
//rbg：线的颜色
//alpha：线的透明度
//返回：圆弧终点坐标，终点为角度大的点，与angle符号无关
function draw_small_arc (mc:MovieClip, ox:Number, oy:Number, r:Number, origin_angle:Number, angle:Number,
thickness:Number, rbg:Number, alpha:Number):Object {
var origin_angle:Number = origin_angle % 360;
var angle:Number = angle % 360;
origin_angle = angle < 0 ? origin_angle + angle : origin_angle;
angle = Math.abs (angle);
angle = angle > 45 ? 45 : angle;
var ctrl_r:Number = maintain_digit (1 / cosD (angle / 2) * r, 4);
var ctrl_sin:Number = maintain_digit (sinD (origin_angle + angle / 2), 4);
var ctrl_cos:Number = maintain_digit (cosD (origin_angle + angle / 2), 4);
var org_sin:Number = maintain_digit (sinD (origin_angle), 4);
var org_cos:Number = maintain_digit (cosD (origin_angle), 4);
var achr_sin:Number = maintain_digit (sinD (origin_angle + angle), 4);
var achr_cos:Number = maintain_digit (cosD (origin_angle + angle), 4);
with (mc) {
lineStyle (thickness, rbg, alpha, false, "normal", "none");
moveTo (org_cos * r + ox, org_sin * r + oy);
curveTo (ctrl_cos * ctrl_r + ox, ctrl_sin * ctrl_r + oy, achr_cos * r + ox, achr_sin * r + oy);
}
return {x:achr_cos * r + ox, y:achr_sin * r + oy};
}
//画小于等于360度的圆弧，任意角度开始
//参数及返回值与draw_small_arc函数相同
function draw_arc (mc:MovieClip, ox:Number, oy:Number, r:Number, origin_angle:Number, angle:Number, thickness:Number,
rbg:Number, alpha:Number):Object {
var origin_angle:Number = angle < 0 ? origin_angle + angle : origin_angle;
var angle:Number = Math.abs (angle);
var times:Number = int (angle / 45);
var last_angle:Number = angle % 45;
if (times >= 8) {
times = 8;
last_angle = 0;
}
for (var i:Number = 0; i < times; i++) {
draw_small_arc (mc, ox, oy, r, 45 * i + origin_angle, 45, thickness, rbg, alpha);
}
return draw_small_arc (mc, ox, oy, r, 45 * times + origin_angle, last_angle, thickness, rbg, alpha);
}
//小数保留
//val：要处理数值
//maintain：保留位数
//返回：处理后的数
function maintain_digit (val:Number, maintain:Number):Number {
var multiple:Number = Math.pow (10, Math.abs (maintain));
return Math.round (val * multiple) / multiple;
}
//以角度为参数计算sin值
function sinD (angle:Number):Number {
return Math.sin (Math.PI / 180 * angle);
}
//以角度为参数计算cos值
function cosD (angle:Number):Number {
return Math.cos (Math.PI / 180 * angle);
}
//随机颜色
function rnd_color ():Number {
return random (255) << 16 | random (255) << 8 | random (255);
}
//弧线颜色数组，由于随机颜色比较丑，所以选择几个比较好的颜色
var color_arr:Array = [0xFF1111, 0xEDB83D, 0xEBEB1D, 0x99E91F, 0x20E91F, 0x23E4E3, 0x1DC2EB, 0x1B45ED,
0x6F1BED, 0xC21BED, 0xEB1DEB, 0xF017AF, 0xF01784, 0xFFFFFF];
//叶子颜色数组，原因同上
var leaf_color_arr:Array = [0x25EB25, 0xF3F347, 0x4AF09D, 0xF2AD48];
//起始角度
var origin_angle:Number;
//弧的角度
var angle:Number;
//弧度是否随机
var angle_rnd:Boolean;
//方向
var dir:Number;
//上一个弧的方向
var old_dir:Number;
//弧的个数
var time:Number;
//弧所在圆的坐标
var posx:Number;
var posy:Number;
//弧终点位置
var pos_obj:Object;
//半径
var r:Number;
//弧线粗细
var thickness:Number;
//是否跟踪
var is_trace:Boolean = false;
//是否有树叶生长效果
var leaf_grow:Boolean = false;
//用于画弧线的mc
var line_mc:MovieClip;
//初始化属性
function init_prop () {
line_mc.removeMovieClip ();
line_mc = this.createEmptyMovieClip ("line_mc", 1);
line_mc.setMask (mask);
line_mc._x = mask._x;
line_mc._y = mask._y;
origin_angle = random (4) * 90;
angle = get_txt_value (angle_txt, 0, 0, 10, 360);
if (angle == 0) {
angle_rnd = true;
} else {
angle_rnd = false;
}
dir = random (2) ? 1 : -1;
posx = random (100) - 50;
posy = random (100) - 50;
time = get_txt_value (time_txt, 50, 10, 10, 200);
r = get_txt_value (r_txt, 20, 5, 5, 50);
thickness = get_txt_value (thickness_txt, 5, 1, 1, 10);
}
//主函数
function main () {
if (--time > 0) {
dir = random (2) ? 1 : -1;
origin_angle += angle;
//如果当前弧的方向与前一个的不同，计算当前弧所在圆的原点位置
if (dir + old_dir == 0) {
posx += cosD (origin_angle) * 2 * r;
posy += sinD (origin_angle) * 2 * r;
origin_angle += 180;
}
if (angle_rnd) {
angle = dir * (random (50) + 50);
} else {
angle = dir * Math.abs (angle);
}
pos_obj = draw_arc (line_mc, posx, posy, r, origin_angle, angle, thickness, color_arr[random (color_arr.length)], 100);
//加载树叶
if (leaf_grow) {
line_mc.attachMovie ("leaf", "leaf" + time, time, {_x:pos_obj.x, _y:pos_obj.y, _rotation:random (360), _xscale:random (50) +
r * 2 + thickness * 5, _yscale:random (50) + r * 2 + thickness * 5, _alpha:random (100) + thickness * 5});
var leaf_color:Color = new Color (line_mc["leaf" + time]);
leaf_color.setRGB (leaf_color_arr[random (leaf_color_arr.length)]);
}
//跟踪
if (is_trace) {
line_mc._x = mask._x - pos_obj.x;
line_mc._y = mask._y - pos_obj.y;
}
old_dir = dir;
} else {
delete line_mc.onEnterFrame;
}
}
//获取文本框内容，为数值
//txt_name：文本框名称
//nan_val：文本内容非数字时所取值
//zero_val：文本内容为0时所取值
//min_val：文本内容最小值
//max_val：文本内容最大值
function get_txt_value (txt_name:TextField, nan_val:Number, zero_val:Number, min_val:Number, max_val:Number) {
if (isNaN (Number (txt_name.text))) {
txt_name.text = String (nan_val);
} else if (Number (txt_name.text) == 0) {
txt_name.text = String (zero_val);
} else if (Number (txt_name.text) < min_val) {
txt_name.text = String (min_val);
} else if (Number (txt_name.text) > max_val) {
txt_name.text = String (max_val);
}
return Number (txt_name.text);
}
//重画
redraw_btn.onRelease = function () {
delete line_mc.onEnterFrame;
init_prop ();
line_mc.onEnterFrame = main;
};
//选择是否跟踪
trace_check.onRelease = function () {
is_trace = !is_trace;
this.gotoAndStop (Number (is_trace) + 1);
};
//选择是否生长树叶
leaf_check.onRelease = function () {
leaf_grow = !leaf_grow;
this.gotoAndStop (Number (leaf_grow) + 1);
};
var keep_moving:MovieClip = this.createEmptyMovieClip ("keep_moving", 2);
var speed:Number = 10;
//移动line_mc
function moving (speedx:Number, speedy:Number) {
keep_moving.onEnterFrame = function () {
line_mc._x += speedx;
line_mc._y += speedy;
};
}
//停止移动
function stop_move () {
delete keep_moving.onEnterFrame;
}
//按钮控制
up_btn.onPress = function () {
moving (0, speed);
};
down_btn.onPress = function () {
moving (0, -speed);
};
left_btn.onPress = function () {
moving (speed, 0);
};
right_btn.onPress = function () {
moving (-speed, 0);
};
up_btn.onRelease = up_btn.onReleaseOutside = down_btn.onRelease = down_btn.onReleaseOutside = left_btn.onRelease =
left_btn.onReleaseOutside = right_btn.onRelease = right_btn.onReleaseOutside = function () {
stop_move ();
};
//键盘控制
var key_lis:Object = new Object ();
key_lis.onKeyDown = function () {
switch (Key.getCode ()) {
case 37 :
moving (speed, 0);
break;
case 38 :
moving (0, speed);
break;
case 39 :
moving (-speed, 0);
break;
case 40 :
moving (0, -speed);
break;
}
};
key_lis.onKeyUp = function () {
stop_move ();
};
Key.addListener (key_lis);
init_prop ();
line_mc.onEnterFrame = main;