The following picture is close to what I intended to achieve, however due to the very high number of particles with the sphere Papervision struggles render it. In this case switching to Flint, and using their 3D particle system would probably be a better idea.

Time to get gritty! The block of code below creates a sphere of Particles. The for loops below increase in specified steps for latitude and longitude, unlike your normal for loop which counts from 0 to whatever in single increments this stepped process enables us to distribute the Particles at an even distance. The sine wave calculation Math.sin(lat*Math.PI/180) is important for placing the particles in a spherical shape. A positive sine wave multiplied by PI divided by 180 creates us a semi-circle, combined with a negative sine wave we get a full circle. With in the two for loops I’ve also added a random if statement so that Papervision doesn’t struggle to render a high number of Particles, but still keeps the shape of a high density particle sphere. It’s also worth noting that I’ve created a class which extends the Particle class in Paperivision called Dot, to which I’m passing the calculated x y z values, these are then stored so that the Particles can be tweened from a random x y z to form a sphere. I’ve done this only for visual reasons!


for (var lat:Number = -90; lat<90; lat+=(360/dens))
{
var radius:Number = Math.cos(lat * Math.PI / 180) * size;
var circumference:Number = (2*Math.PI*radius);
var numberOfDots:Number = Math.floor(dens*circumference)/size;

for (var long:Number = 0; long<360; long+=(360/numberOfDots))
{
if (Math.floor(Math.random()*8) == 1)
{
part = new Dot(Math.cos(long*Math.PI/180)*radius,
Math.sin(lat*Math.PI/180)*size,
Math.sin(long*Math.PI/180)*radius );
this.particleArray.push(part);
this.particleHolder.addParticle(part);
}
}
}

Click below in order to activate the Flash movie.

The following is a no flash image

In end the outcome above is close to what I intended to achieve, however the density of the dots around the latitude axis is exactly the same at the poles as the equator. I've tried to resolve the density problem but without success, mainly due to Papervision struggling to render such a high density of Particles. I'm realistically on the edge of Math skills and perhaps purchasing a 3D Math primer would be a good idea. Anyway this was an interesting experiment which I got very close to getting it right.

A couple of months ago I created a couple of classes to handle xml from Twitter for a potential flash feed thingy. The classes consisted of a model class which creates business objects like tweets and user, making the data easily mangaged/accessible within a project. Using these classes I’ve just added a bit of Papervision, the text is displayed via the Text3D class which is really nice class if your project uses Helvetica and some what devoid if it doesn’t.

Flash is displayed here

Flash is displayed here

Step 1
After setting up a basic Papervision environment with a sphere, the next thing to do is add a particle to the edge of the sphere. Within Papervision its not possible to just create a new Particle, and it add it the scene, instead the Particle must be added to an instantiation of the Particles class, which acts as holding container for a Particle. It is worth noting that thousands of individual Particles can be added to the Particles container and then added to the scene to be rendered.

var material = new ParticleMaterial(0xFF3333, 1);
var particle = new Particle(material, 15);
this.particles = new Particles();
this.particles.x =-294.8020952990483;
this.particles.z = -44.981004334405526;
this.particles.y = 47.67005198611658;
this.particles.addParticle(particle);
this.sphere.addChild(this.particles);


Step 2
In order to map a 2D Sprite to a 3D object we need to calculate the 3D objects relative position in x and y to the screen. Luckily by adding the following line to the previous code block this functionally can be switched on. The method autoCalcScreenCoords is available to any class which extends DisplayObject3D, however user must be careful as extra calculations are made with the potential for a performance drop if used with out.

this.particles.autoCalcScreenCoords = true;


Step 3
The screen x and y are always calculated relative to the size of the viewport being used. I’ve added the following couple of lines of code, within the render EnterFrame only so that the 2D Sprite is always mapped to the 3D object but of course could exist elsewhere.

this.triangle.x = ( this.particles.screen.x ) + (this.viewport.width / 2);
this.triangle.y = ( this.particles.screen.y ) + (this.viewport.height / 2);

And that’s it, pretty basic stuff yet can still be very useful.

Source code