I am the author of an After Dark freeeware screensaver
module called 'The Swarm' which is a straightforward port of
the classic Unix 'xswarm' program. (You can go to
screenshots of the module, or for downloading it).
The bees in the swarm are simply coloured line segments.
Every frame of the animation, I draw the bees into a GWorld,
I calculate the enclosing rectangle of the entire swarm, and
I blit that onto the real screen using CopyBits (after
blacking out the previous frame's rectangle first).
This approach yields acceptable performance for
not-too-large swarms, even on 68k machines. However, what
has always been bugging me about my implementation from the
very beginning, is that if I profile the code it turns out
that in a frame of the animation the most time is *not*
spend on the two CopyBits calls (as I had been expecting),
but rather on the LineTo calls used to draw the individual
bee line segments.
I find it hard to believe that drawing twenty or thirty line
segments into a GWorld would be that performance-intensive
(and it is not the function call overhead either, I've
So, can anybody out there explain to me *why* LineTo is so
computation-intensive, or better yet: suggest an alternative
approach for drawing lines that might yield better results?