Biased Random Particle Distribution

I wish there were more discussions like this...

I experimented a bit with this with some curving equations,
this is what I
have to contribute:

import flash.geom.Point;
var particleAmount = 100;
var particles = [];

var radiusMin = 3;
var radiusMax = 100;

function createParticles(){
    var i = -1, l = particleAmount, a = 0, rDiff = radiusMax
- radiusMin;
    while(++i<l){

        a = Math.pow(2, 10 * (i/l-1));
        //a = Math.sin((Math.PI/2)*i/l);
        trace(a);

        var radius = a*rDiff;

        //var theta = Math.random()*Math.PI*2;
        var theta = (i/l)*(Math.PI*2);
        //var theta = 0;

        particles.push(Point.polar(radius, theta));
    }
}

function drawParticles(){
    var i = -1, l = particles.length;
    _root.createEmptyMovieClip('emc', 1);
    _root.emc._x = Stage.width/2;
    _root.emc._y = Stage.height/2;
    _root.emc.lineStyle(1, 0x000000, 100);
    //trace(particles);
    trace(particles.length);
    while(++i<l){
        var a = particles[i].x*3, b = particles[i].y*3, c =
a, d = b + 1;
        _root.emc.moveTo(a,b);
        _root.emc.lineTo(c,d);
    }
}

createParticles();
drawParticles();

Variable a is a set of different equations that will create
curves, the
equation that uses pow uses an exponential curve. The
Math.sin one uses a
simple sin curve. The theta can be swaped around too to
check out the effect
the equations give.

I noticed you mentioned creating a bias on the right side of
a rectangle
too, I think you can do this by using a range for the x
property of a point
instead of the radius.

M.

On 5/26/06, clark slater <slater.clarkgmail.com> wrote:
>
> I need to randomly distribute a series of particles in
a 2D space with a
> bias towards the zero point for both dimensions. I know
how to create a
> biased distribution towards the center (thanks Keith
peters) by averaging
> a
> series of throws - but I am stuck on the zero bias
distribution.
>
> Any ideas? I guess I need something like an exponential
decay curve?
>
> Clark
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