this morning I found out that there's not much for me to do today, so
I decided to take a look at the XScreenSaver hacks (the X11 stuff, not
the OpenGL ones) to see if it'd be easy to port them to Plan9...

I was familiar with galaxy.c from an old project I did at usask.ca, so
that was my first choice..

I found out that it's amazingly easy to port (this one specifically)
since there's not much to it -- it calculates pixels and draws them on
the screen.  nothing complex...

so, here it is -- compile and run in a window to see how fast it'll go...

what's missing:
	colors, number of stars was reduced to 1000 (from 3000) to
	display faster, the whole galaxy thingie was rotating around
	the viewpoint.  it was puke-inducing so i removed it

	license -- some parts of xscreensaver think they're under the
	GPL (like the autoconf scripts and some hacks), others do
	not...  no autoconf was used, so no GPL :)

what's added:
	menu (right mouse button exits)
	increased pixel size by 1, it seems to look better on my
	screen
	fps calculation -- the fps will be given upon exit, note that
	it's cpu-bound, rather than graphics-bound

originally galaxy.c kept track of old pixels and filled them in with
black, then drawing the new ones.  this seems to be slower for plan9,
since P9 doesn't have something resembling XDrawPixels() with which to
draw an array of Points (i.e.  each pixel is currently a call to
draw() with a 2x2 rectangle argument).  in this case it's better to
redraw the screen with black at the beginning of each iteration and
then just fill in the white spots one by one...

I'll do more when I have some more time (likely soon :) -- there's
plenty where this one came from :)

andrey

ps: some data, if anyone's interested:
	(all done in a brand new window started with the 'window'
	command)

	GeForce3 video card, athlon 800mhz, 32bpp, gives 20+fps with 3
	galaxies, 26+ with 2