spline1

昔NHKのどっかの番組で見たやつ
別に不変じゃなくてもいいのは小文字

by uwi 07 Jan 2009

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line point typographic
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// 昔NHKのどっかの番組で見たやつ
// 別に不変じゃなくてもいいのは小文字
package {
    import flash.display.*;
    import flash.events.*;
    import flash.text.*;
    import flash.filters.*;
    import flash.geom.*;

    [SWF(width=465,height=465,frameRate=30,backgroundColor=0xffffff)]
    public class Outliner extends Sprite {

        private const N : int = 1000;
        private const str : String = "あこるでぃおん"; // 空白文字入れちゃﾀﾞﾒﾃﾞｽﾖｰ
        private const tfmt : TextFormat = new TextFormat("ＭＳ 明朝", 100);
        private const step : Number = 0.02;
        private const scale : Number = 5;

        private var t : Number = -1; // 停止時間を設けるため余裕を持たせてある
        private var xcvec : Vector.<Object> = new Vector.<Object>();
        private var ycvec : Vector.<Object> = new Vector.<Object>();

        public function Outliner() {
            var i : int;
            var pvec : Vector.<Vector.<Point>> = new Vector.<Vector.<Point>>();
            var vec : Vector.<Point>;

            var cf : ConvolutionFilter = new ConvolutionFilter(3, 3, [0, -1, 0, -1, 4, -1, 0, -1, 0]);

            for(i = 0;i < str.length;i++){
                var bmd : BitmapData = getTextBitMap(str.charAt(i), tfmt);

                // エッジ抽出
                bmd.applyFilter(bmd, bmd.rect, new Point(), cf);    

                // 輪郭上の点を得る
                vec = new Vector.<Point>();
                var offset : Point = new Point(stage.stageWidth / 2 - bmd.width / 2, stage.stageHeight / 2 - bmd.height / 2);
                while(vec.length < N){
                    var p : Point = new Point(Math.random() * bmd.width, Math.random() * bmd.height);
                    if(bmd.getPixel(p.x, p.y) == 0xffffff){
                        vec.push(p.add(offset));
                    }
                }
                pvec.push(vec);
            }

            // 各点についてB-splineの係数を求めておく
            for(i = 0;i < N;i++){
                var xvec : Vector.<Number> = new Vector.<Number>();
                var yvec : Vector.<Number> = new Vector.<Number>();
                for each(vec in pvec){
                    xvec.push(vec[i].x);
                    yvec.push(vec[i].y);
                }
                xcvec.push(Spline.calcCoordinate(xvec));
                ycvec.push(Spline.calcCoordinate(yvec));
            }

            addEventListener(Event.ENTER_FRAME, onEnterFrame);
        }

        private function onEnterFrame(e : Event) : void
        {
            graphics.clear();
            graphics.beginFill(0x000000);
            graphics.lineStyle(0);

            var ut : Number = t;
            if(ut < 0)ut = 0;
            if(ut > str.length)ut = str.length;
  
            var i : int;
            for(i = 0;i < N;i++){
                // 補間計算
                var x : Number = Spline.calc(xcvec[i], ut);
                var y : Number = Spline.calc(ycvec[i], ut);

                // 中央に関してscale倍
                x = (x - stage.stageWidth / 2) * scale + stage.stageWidth / 2;
                y = (y - stage.stageHeight / 2) * scale + stage.stageHeight / 2;
//                graphics.drawCircle(x, y, 1);
                graphics.drawRect(x - 1, y - 1, 2, 2);
            }

            graphics.endFill();

            t += step;
            if(t > str.length + 1)t = -1;
        }

        private function tr(s : String) : void
        {
            var tf : TextField = new TextField();
            tf.autoSize = TextFieldAutoSize.LEFT;
            tf.text = s;
            addChild(tf);
        }

        // テキストをBitmapDataに変換
        private static function getTextBitMap(text : String, tfmt : TextFormat) : BitmapData {
            var tf : TextField = new TextField();
            tf.autoSize = TextFieldAutoSize.LEFT;
            tf.defaultTextFormat = tfmt;
            tf.text = text;

            var ret : BitmapData = new BitmapData(tf.width, tf.height, true, 0xffffffff);
            ret.draw(tf);
            return ret;
        }
    }
}

// @see http://www5d.biglobe.ne.jp/~stssk/maze/spline.html
class Spline {
    public static function calc(cs : Object, t : Number) : Number
    {
        var p : int = Math.floor(t);
        if(p >= cs.a.length)p--;
        var dt : Number = t - p;
        return cs.a[p] + (cs.b[p] + (cs.c[p] + cs.d[p] * dt) * dt) * dt;
    }

    public static function calcCoordinate(a : Vector.<Number>) : Object
    {
        var n : int = a.length;

        var b : Vector.<Number> = new Vector.<Number>();
        var c : Vector.<Number> = new Vector.<Number>();
        var d : Vector.<Number> = new Vector.<Number>();
        var w : Vector.<Number> = new Vector.<Number>();

        var i : int;

        c.push(0);
        for(i = 1;i < n - 1;i++){
            c.push(3 * (a[i + 1] - 2 * a[i] + a[i - 1]));
        }
        c.push(0);

        w.push(0);

        for(i = 1;i < n - 1;i++){
            var l : Number = 4.0 - w[i - 1];
            c[i] = (c[i] - c[i - 1]) / l;
            w.push(1.0 / l);
        }
        for(i = n - 2;i > 0;i--){
            c[i] -= c[i + 1] * w[i];
        }


        for(i = 0;i < n - 1;i++){
            d.push((c[i + 1] - c[i]) / 3.0);
            b.push(a[i + 1] - a[i] - c[i] - d[i]);
        }
        b.push(0);
        d.push(0);
            
        return {a : a, b : b, c : c, d : d};
    } 
}