How to create randomly flying away movie

1 //Destination "X" and "Y" coordinates
2 var XFA,YFA; //Assign this variables on "_parent".
3 var QXsC; //Number of steps
4 var IDesc; //If this variable is "true", the object will disappear, otherwise it will appear
5 if(IDesc==null)
6 IDesc=true;
7
8 var XB,YB; //Global variables to remember initial position of "this" movie
9
10 var AAlpha; //Angle of slope of the segment between (XB,YB) and (XFA,YFA)
11 var A0; //First coefficient of random polynomial, by what the movie will move
12 var XsRM,XsRFA; //Second and third roots of the polynomial in turned coordinates
13 var XsC; //Current "X" coordinate when "this" is moving (in turned coordinates)
14 var DXsC; //"X" step of movement in turned coordinates
15 var NXsC; //Step number
16
17 var IRun=null; //Action director
18 /*f***********/
19 function flyAwayRandomly()
20 {
21 //We came here after button was clicked
22 findPolynomialRandomly();
23 //Let's begin moving!
24 IRun=0;
25 }
26 /*f***********/
27 function findPolynomialRandomly()
28 {
29 var tanAlpha; //Slope of the segment between (XB,YB) and (XFA,YFA)
30 var xmax1,xmax2;
31 var dxr;
32
33 //Let's remember initial position of "this"
34 XB=_x;
35 YB=_y;
36
37 //Calculate angle of slope
38 if(XFA!=XB)
39 {
40 //If the direction of the destination is not vertical:
41 tanAlpha=(YFA-YB)/(XFA-XB);
42 AAlpha=Math.atan(tanAlpha);
43 if(XFA 44 AAlpha+=Math.PI;
45 }
46 else
47 {
48 //Calculate angle of vertical directions (straightly up and down):
49 AAlpha=Math.PI/2;
50 if(YFA 51 AAlpha+=Math.PI;
52 }
53
54 //Find "farthest" root of the polynomial
55 if(XFA!=XB)
56 XsRFA=(XFA-XB)/Math.cos(AAlpha);
57 else
58 XsRFA=Math.abs(YFA-YB);
59
60 //Find "middle" root of the polynomial
61 XsRM=XsRFA/4;
62 dxr=random(Math.abs(XsRFA))/2;
63 if(XsRM<0)
64 dxr=-dxr;
65 XsRM+=dxr;
66
67 //Find "elder" coefficient of the polynomial
68 A0=1;
69 xmax1=Math.abs(polRan((XsRM+XsRFA)/2));
70 xmax2=Math.abs(polRan(XsRM/2));
71 xmax1=Math.max(xmax1,xmax2);
72 A0=1/xmax1*50;
73 //Sometimes it is positive, sometimes - negative
74 if(random(2))
75 A0=-A0;
76
77 //Find "X" step of moving
78 DXsC=XsRFA/QXsC;
79
80 //Assign X in turned coordinates
81 XsC=0;
82 //Initialize step number
83 NXsC=0;
84 }
85 /*f***********/
86 function fnOnEnterFrame()
87 {
88 //On every frame we are here from "Timer"
89 if(IRun!=null)
90 moveThis();
91 }
92 /*f***********/
93 function moveThis()
94 {
95 var ysC;
96
97 if(NXsC>=QXsC)
98 {
99 //If "this" movie has reached destination,
100 //we do not allow it to move further,
101 //and preparing to stop
102 IRun=1;
103 XsC=XsRFA;
104 }
105
106 //Calculate "Y" by "X" in turned coordinates
107 ysC=polRan(XsC);
108
109 //Convert turned coordinates to used in Flash
110 _x=XB+XsC*Math.cos(AAlpha)-ysC*Math.sin(AAlpha);
111 _y=YB+XsC*Math.sin(AAlpha)+ysC*Math.cos(AAlpha);
112
113 //Decrease scales of "this" movie
114 if(IDesc)
115 _xscale=(QXsC-NXsC)/QXsC*100;
116 else
117 _xscale=NXsC/QXsC*100;
118 _yscale=_xscale;
119
120 //Step forward
121 XsC+=DXsC;
122 if(IRun==1)
123 {
124 //Call the callback function to inform "_parent" that the moving is over
125 _parent.cbFinished(this);
126 //Stop the moving
127 IRun=null;
128 }
129
130 NXsC++;
131 }
132 /*f*****************************************************
133 This function calculates result
134 of our polynomial in "Xsc"
135 *******************************************************/
136 function polRan(XsC)
137 {
138 var ys;
139 ys=A0*XsC*(XsC-XsRM)*(XsC-XsRFA);
140 return ys;
141 }