Example
output and documentation appear below:<p>
<img WIDTH=500 HEIGHT=341 src=s102-normal.jpg><p>
Here's the alpha channel in action (rendered over solid noise):<p>
<img WIDTH=256 HEIGHT=256 src=alpha.jpg><p>
Here's the result of setting the variation to spherical, and then
layering many flames over a white background:<p>
<img WIDTH=256 HEIGHT=256 src=var.jpg><p>

Here are screen-shots of the UI. The main window:<p><img WIDTH=364 HEIGHT=681 src=main.gif><p>And the shape edit window:<p><img WIDTH=351 HEIGHT=496 src=edit.gif><p>  The colormap can be set to
the current gradient, one of several presets, or a set of colors from an
image in another window.  The Smooth Palette plug-in (below) is good for
creating such images.  The "Sample Density" widget controls how accurate
the rendering process is (and hence how long it takes to compute).  It
does not effect the preview (which is always computed at low sample
density).<p>
The center image in the edit window shows the current shape.  When you
click "ok, this shape is returned to the main window.  The eight
surrounding images indicate possible ways of changing the current
shape.  Clicking on one replaces the current shape with that image.
Clicking on the center image picks eight new random directions.
Clickon on "randomize" replaces the current shape with a new random
shape.  The "variation" menu controls the overall character of
the shapes.