🚀 go-pugleaf

In article <3bm8d9$p...@harbinger.cc.monash.edu.au>,
GM Enierga <gme...@lindblat.cc.monash.edu.au> wrote:
>j-h...@ux4.cso.uiuc.edu (James Hogan) writes:
>>Already in the works.  :)  Try Alt-4 if nothing else works.  After that 
>>try Alt-3... that should speed it up on some video cards (particularly if 
>>you have a good VLB one), though it may slow it down on others.  
>
>	What EXACTLY does the ALT-4 combination supposedly do?  And the alt-1
>& 2 combos?
>	So what version are you going to call the new one? :-)
>
>						- Falcon
>
Origin says ALT-3 does single-buffering, and ALT-4 does triple-buffering.
ALT-1 is equivalent to ALT-3, but in VGA, and ALT-2 is equivalent to ALT-4.
It's possible that ALT-1 uses double-buffering, but that's similar enough
to single-buffering that it doesn't really matter for this discussion.

Anyway, here's what it boils down to:  ALT-3 (and ALT-1) produce the frame
in memory, then stuffs it to the video card as fast as the bus can handle
it.  This works great if you have a fast video card and local bus, and
requires minimal CPU time.  It's called single buffering because only a
single frame is stored in memory at a time.

Triple-buffering is much more complex.  Suppose the computer has just finished
drawing a frame.  The CPU calculates the next frame, and then compares it to
the frame it just drew.  Then it ONLY draws the pixels that have changed to
the monitor.  This is impressive stuff, and is extremely efficient if you
have a slow card or bus, but a fast computer.  However, it does require
significantly more CPU time.  Origin is the only company I know of that
bothers to implement something this difficult, and my hat goes off to them
for it.  It's called triple-buffering because the previous frame, the current
frame, and the pixels to change (three items) are all stored in memory at 
the same time.

To prove how impressive a technique this is, I'll use my system as an
example.  I recently purchased a Pentium motherboard, but haven't had the
chance to put a new video card in it.  WC3 rates it:

0 for CPU
17 (!!) for my ISA Trident 8900C.

In VGA, I get 24 frames per second no matter what.
With ALT-3, I get 5 frames per second.  Always.  My video card simply cannot
accept faster rates than that.  However...
With ALT-4, I get 24 frames per second in clear sky.
                  20-24 frames per second when dogfighting, and
         at worst 7 frames per second when those Rookies run into me,
which only lasts for a frame or two anyway

All you Origin bashers: THAT is good programming.  Yet it's the kind of thing
that you could never know about just by playing the game, unless you had
a pretty good idea of how these things worked.  And they've been using this
same technique AT LEAST since the floppy version of Strike Commander!
Their only mistake was not anticipating that local bus video would make this
technique obsolete... and that problem was fixed in the CD release.

Uh, anyway, that's the difference between the video modes in WC3.  Sorry
you asked?  ;)

-Jim Little  (ji...@teleport.com)