2線交点2

/**
 * Copyright hashito ( http://wonderfl.net/user/hashito )
 * MIT License ( http://www.opensource.org/licenses/mit-license.php )
 * Downloaded from: http://wonderfl.net/c/tpZS
 */

// forked from hashito's 文字集まる修正
// MainStage
package {
    import flash.display.Sprite;
    [SWF(frameRate=60,width=456,height=456)]
    public class MainStage extends Sprite {
        public function MainStage(){
            addChild(new Main());
        }
    }
}

import flash.display.*;
import flash.filters.BlurFilter;
import flash.geom.Point;
import flash.geom.ColorTransform;
import flash.events.*;
import flash.utils.Timer;
import flash.text.TextField;
import flash.text.TextFormat;
import net.hires.debug.Stats;
// debug
class debug{public static var out:TextField=new TextField();}

/*t.hashito*/
class MF{
    public static function AFFORD (x:Number,aim:Number,a:Number):Boolean{return (x<=(a+aim))&&(x>=(a-aim));}
    public static function RAN (n:Number=1):Number{return (Math.random()*n);}
    public static function ISPM (n:Number):Number{if(n<0){return -1;}else if(n>0){return 1;}return 0;}
    public static function MAX (n:Number,max:Number):Number{return (n>max)?max:n;}
    public static function MIN (n:Number,min:Number):Number{return (n<min)?min:n;}
    public static function LIMIT (n:Number,max:Number,min:Number):Number{if(n>max){return max;}else if(n<min){return min;}else{return n};}
    public static function RAD_ANG(n:Number):Number{return n*180/Math.PI}
    public static function ANG_RAD(n:Number):Number{return n*Math.PI/180 }
    public static function LATCH(v:Boolean,s:Boolean,r:Boolean):Boolean{if(s)v=true;if(r)v=false;return v;}
    public static function ONE_SHOT_ON(v:Boolean,o:Boolean):Boolean{var r:Boolean = (v==(!o));o=v;return r;}
    public static function DOT2(x1:Number,y1:Number,x2:Number,y2:Number):Number{return x1 * x2 + y1 * y2; }//内積
    public static function SLOPE(x1:Number,y1:Number,x2:Number,y2:Number):Number{if((x1-x2)!=0)return (y1-y2)/(x1-x2);return 0; }//傾き
}

class Main extends Sprite{
    public const H:Number = 456,W:Number = 456;
    public var mx:Number = 0,my:Number = 0;
    public var ksp:Boolean   = false;
    public var la:Shape   = new Shape(),la1x:Number,la1y:Number,la2x:Number,la2y:Number;
    public var lb:Shape   = new Shape(),lb1x:Number,lb1y:Number,lb2x:Number,lb2y:Number;
    public var cross:Shape   = new Shape();
    public var selectball:Shape   = new Shape();
    public var select:int = 0;
    public const SELMAX:int = 4;
    
    // constructor
    public function Main() {addEventListener(Event.ADDED_TO_STAGE, init);}
    // init
    public function init(e:*):void{
        // debug
        debug.out.autoSize=flash.text.TextFieldAutoSize.LEFT;
        addChild(debug.out);
        
        la1x = MF.RAN(W);
        la1y = MF.RAN(H);
        la2x = MF.RAN(W);
        la2y = MF.RAN(H);
        lb1x = MF.RAN(W);
        lb1y = MF.RAN(H);
        lb2x = MF.RAN(W);
        lb2y = MF.RAN(H);
        //line init
        addChild(la);
        addChild(lb);
        
        // cross init
        cross.graphics.beginFill(0x000000);
        cross.graphics.drawCircle(0,0,3);
        addChild(cross);
        
        // selectball init
        selectball.graphics.beginFill(0x00ffff);
        selectball.graphics.drawCircle(0,0,3);
        addChild(selectball);
        
        addEventListener(Event.ENTER_FRAME ,ef);
        stage.addEventListener(KeyboardEvent.KEY_DOWN ,key);
        
        var s:Stats = new Stats();
        addChild(s);
    }
    public function key(e:KeyboardEvent=null):void{
        if (e.keyCode == 32) {// space
            if(SELMAX <= ++select)
                select = 0;
        }
    }
    
    public function ef(e:Event=null):void{
        mx = mouseX;
        my = mouseY;
        
        if(select == 0){        la1x=mx;la1y=my;
        }else if(select == 1){    la2x=mx;la2y=my;
        }else if(select == 2){    lb1x=mx;lb1y=my;
        }else if(select == 3){    lb2x=mx;lb2y=my;
        }else{}
        
        selectball.x=mx;
        selectball.y=my;
        
        la.graphics.clear();
        la.graphics.lineStyle(2,0xff0000);
        la.graphics.moveTo(la1x,la1y);
        la.graphics.lineTo(la2x,la2y); 
        
        lb.graphics.clear();
        lb.graphics.lineStyle(2,0xffff00);
        lb.graphics.moveTo(lb1x,lb1y);
        lb.graphics.lineTo(lb2x,lb2y);
        
        
        
        var wk:Number,a:Number,b:Number;
        a = MF.SLOPE(la1x,la1y,la2x,la2y);
        b = MF.SLOPE(lb1x,lb1y,lb2x,lb2y);
        wk = (a - b);
        
        cross.x = 0;
        cross.y = 0;
        
        if(wk!=0)
            cross.x = (a*la1x - b*lb1x + lb1y - la1y)/wk ;
        cross.y =  a*(cross.x - la1x) + la1y
                
        //debug.out.text="x="+t.bits[0].x+" y="+t.bits[0].y+" vx="+t.bits[0].vx+" vy="+t.bits[0].vy+" ax="+t.bits[0].ax+" ay="+t.bits[0].ay;
    }
}