  Plasma fractals is a technique to generate random and realistic clouds,
textures and terrains~-- traditionally using recursive subdivision. We
demonstrate a new approach, based on iterative expansion. It gives a family of
algorithms that includes the standard square-diamond algorithm and offers
various interesting ways of extending it, and hence generating nicer pictures.
The approach came about from exploring plasma fractals from the point of view
of an array language (which we implemented as an embedded DSL in OCaml)~-- that
is, from the perspective of declaring whole image transformations rather than
fiddling with individual pixels.
