1) Actually drawing the rocket paths, using the drawing API
2) Dumping the paths to a bitmap object periodically to prevent memory drain
3) Slowly changing the colour of the paths to get some distinction between generations.

1: In order for the rockets to draw their paths, they simply draw a line using the drawing API from their last known position to their current position. All of the rocket paths are drawn to the same MC, named ‘thecanvas_mc’. This code is, of course, called once per frame.

_root.thecanvas_mc.moveTo(lastx, lasty);
_root.thecanvas_mc.lineTo(_x, _y);
lastx = _x;
lasty = _y;

2: With 25 rockets drawing a line once per frame, the sheer number of lines rises very quicky. Within a second, we have 750 lines. This will get out of control fast, draggin down the speed of our program. To remedy this, we ‘dump’ the line data from thecanvas_mc into a BitmapData object. This BitmapData object is rendered to screen.

I am using an instance of my Canvas Class, which is available here.

//setup:
var can = new Canvas(_root);

//drawing:
doDraw = function() {
can.etch(thecanvas_mc);
thecanvas_mc.clear();
};

setInterval(doDraw, 100);

3: To create a color gradient in the lines that are drawn, I simply adjust the values of R,G & B in the lines that are being drawn:

//setup:
r = 0;
g = 0;
b = 0;
rv = Math.random() / 10;
gv = Math.random() /10;
bv = Math.random() /10;

//drawing:
doDraw = function() {
can.etch(thecanvas_mc);
thecanvas_mc.clear();

r += rv;
g += gv;
b += bv;

var c = argbtohex(25,r,g,b);
thecanvas_mc.lineStyle(1, c, 10);
};

Hopefully this helps. If you still want to see the whole source, let me know.

-Jer