3Dfx's 60Hz/30Hz/15Hz demo
--------------------------
Copyright 3Dfx Interactive, Inc. 1998.


Brought to you by the Voodoo Programming Group,
VPG, at 3Dfx Interactive, Inc.
Programmed by Denis Amselem.

The purpose of the demo is to illustrate
the differences between 60 fps and lower
frame rates like 30 fps or 15 fps.
We do believe that 60 fps provides a much better
visual experience than 30 fps and we would like
to warn people about turning on higher quality image
features to the detriment of the frame rate.

Why is 60hz so much better than 30hz?
-------------------------------------
Well, see for yourself. Use the predefined camera
positions that are available by pressing keys '1' thru '9'.
'3': wait until the white 3Dfx texture (applied to one of the
paintings on the wall) appears. Check out the difference
between the left screen and the right screen. Notice
how the 60Hz image is much sharper than the 30Hz one.
The 3Dfx texture on the 30Hz screen looks blurry
and shaky when it passes by the camera.
'4': concentrate on the bouncing ball. Same thing here: notice
how fluid and smooth the bouncing ball is on the left screen,
and how blurry it is on the right screen.
'2': you can see both the bouncing ball and 3Dfx texture on the wall.


So, what's going exactly?
-------------------------
It's pretty simple: you get twice as many frames (or images)
with a game running at 60hz than you do with a game
running at 30Hz (or 4 times as many than with a game running
at 15Hz). So, your eyes getting more images, your brain doesn't
have to resort to doing as much interpolation (leading to bluriness)
as it has to in the 30Hz case.
To see exactly what's going on, press the '.' key:
this will switch the demo to a mode where the scene
is upated frame by frame.
Each time you press the '.' key, we move to the next frame.
Notice how the scene on the right screne is updated only
every over frame while the one on the left is updated at each frame.
Turn on the 15Hz mode (using the 'R' key), and verify that
it takes 4 new frames on the left screen before a new one
is displayed on the right one.

In pratice:
-----------
Sure, 30Hz is already a pretty good frame rate and most games
and 3D applications are quite usable at this rate.
At 60Hz however, the additional images provides both a more
comfortable visual experience and a better reactivity to
what's going on the screen: more images allows for better
interpolation and more accurate prediction of where a moving
object is going to be (think 'target' for example :-).


Bottom Line:
------------
Aim for 60Hz whenever you can, and think twice before
turning on some features that would slow down the frame rate
too much.



Starting and Running the Demo
-----------------------------

//Step1//
For Voodoo2 users: go to step 2/.

For Banshee users:
This step is optional if you don't want absolute 60/30
refresh rates values, but only care about the 2x or 4x
frame rate ratio between the 2 screens (see Notes below).

The first thing to do is to make sure that your monitor
has a maximum refresh rate of 60Hz.
For that, you need to:
- set you Windows desktop resolution to 640x480.
- set your monitor refresh rate to 60Hz. For that,
  open the Display Properties sheet, and click on
  the advanced button. It should open a "3Dfx Voodoo Banshee ..."
  propertie sheet. Select the "Adapter" page, and modify
  the refresh rate value (which should be set to Optimal by default).


Notes:
  If you don't force your monitor to 60Hz, you can still observe
  the differences between the left screen and the right screen.
  The ratio between the frame rates will always be 2x or 4x, it's
  just that the absolute frame rate won't be necessarly 60 and 30 (or 15).

  Don't forget to reset your monitor refresh rate value to optimal
  once you are done playing with the demo.

  If you want to run the demo at 800x600 or 1024x768, you'll have to
  start Step1 over again, using the new resolution.
  



//Step2//
To start the demo, simply type:
demo6030.exe

it will start the demo in 640x480 mode.

For higher resolution modes, start the demo
with the -r option followed by the corresponding
resolution constant.
The supported mode are:
comdex -r 1024x768
comdex -r 800x600
comdex -r 640x480 (default)


The demo starts with the Help screen displayed
by default. Just press H to get rid of it.


Help screen
-----------
Press 'H' to toggle the help screen on and off.
Press 'R' to toggle right screen between 30Hz and 15Hz.
Press 'space bar' to toggle rotation of the screen.
Press 'B' to toggle the bouncing of the ball.
Press '.' (or '>') to step frame by frame (and press
        any other key to return to regular mode).

Press 'q' to quit.



Misc. Commands:
---------------

Use the Arrow keys to move around:
Up Arrow: move forward in the direction the camera is facing.
Down Arrow: move backward along the direction the camera is facing.
Right Arrow: rotates the camera to the right.
Left Arrow: rotates the camera to the left.

Shift + Up Arrow: makes the camera Look Up.
Shift + Down Arrow: makes the camera Look Down.

CTRL + Up Arrow: translates the camera Up.
CTRL + Down Arrow: translates the camera Down.


keys 1 through 9 switches the camera to predifined positions
(and predefined modes, like if the sphere is bouncing or not,
if the scene is spinning or not, etc...).


You can define your own predefined camera/modes by getting
tot the right camera position (using the Arrow keys) and
setting the right modes (using B, P, Space Bar etc...),
and Pressing CTRL+'Predefined Position Number'.
For example, if you press
CTRL + 4
the current position and modes will be saved as position 4.

You can then move around, or go to any of the other
predefined positions, and the next time you press 4, it will
take you back to the same location.









