This experiment applies the approach I described in
Applying Noise to Particle Clouds.
The applet to the right is gradually building up
a cloud volume from back to front,
by stacking thin translucent layers one in front of another.
This back-to-front approach also lets me build up a parallel "shadow volume" so that the cloud can cast a shadow on itself (which makes it much easier to see the shape).
The basic density cloud consists of 200 overlapping fuzzy particles.
When you click "Texture on" button, then procedural noise is added to the density cloud, and the whole thing looks much more interesting.
Texture on Texture off
vpuff extends VolumeApplet extends PixApplet