Blood 3DFX ALPHA 1.20

Notes from 3DFX


3Dfx Build Engine Version 1.0
Author: Scott Alden from 3DFX

Implementation Notes
--------------------
I had a lot of fun and challenges on working on the
Build engine, not everything went as I wanted it
and many things are workarounds.  Sloped floors
were especially fun ;-) An ideal thing to happen is this
engine is converted to true polygon rendering system.
This could greatly enhance the speed for the 3Dfx hardware.  

I currently have the raster layer of the build engine
rendering spans to the 3Dfx hardware. Thus a wall that
fills the entire screen would be made up of X triangles
where X = the horizontal resolution of the screen.
You can set the BUILD_TRICOUNT (see below) environment
variable to see how many triangles are being drawn on 
the previous frame.  This is more for seeing how the 
tricount affects the framerate.

All of the tiles in the game are downloaded to the
hardware as texture maps, and the span is converted
to the 3Dfx format for rendering.  There are 3 types
of primitives that I use: horizontal triangles for 
horizontal spans, vertical triangles for vertical spans,
and quads for drawing unclipped sprites.  

Also, the lighting/palette effects that the game 
uses are achieved by downloading a new palette to the
3Dfx hardware.  This palette downloading happens on
a span by span basis.  Fog and other lighting effects
are all achieved by palette changing.

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Here are some extra things to know about for 
additions I have made to the build engine which
can be set in your environment before running
the game:

Environment Variables
---------------------
The BUILD_640X480 environment variable is used
to run the game in the 640x480 resolution.  
The default setting is 0, and the default resolution
is 512x384.
e.g. set BUILD_640x480=1

The BUILD_RESAMPLE environment variable is used
to control how the game and animation textures
are converted to 3Dfx format.  If you set this
variable, the slower method of sampling and blending
is used.  This gives a more desirable image however
it takes a long time to run, and it gives a dark
halo effect surrounding sprites (i.e. the fists
and some menu bar things).  The faster way uses
point sampling, it provides a more grainy conversion,
but is a lot faster than the previous method.  
You only need to convert the textures the first time
you run the program, and if you want to recreate
them, delete the "tx3dfx" and animxxxx directories
which contain all the .3df files.

The BUILD_BRIGHTNESS environment variable is used to 
brighten the colors of the textures that are used in
the game engine.  The colors will be brightened by this
factor, and will saturate to white.  The default setting
is 2.5.  
e.g. set BUILD_BRIGHTNESS=2.8

The BUILD_NOPAL environment variable is used to turn
on palette downloading on a per-span basis.  
!!!Warning!!! This will affect the color palette of the game
and the colors may not be correct!  This is only provided
as a speed boost.  The default setting is 0.
e.g. set BUILD_NOPAL=1

The BUILD_NOFOG environment variable allows the game
fog to be turned on/off.  This is provided as a
speed boost.  The default setting is 0.
e.g. set BUILD_NOFOG=1

The BUILD_CONVTEXTURES environment variable is used
to control whether or not textures are cached to disk.
If BUILD_CONVTEXTURES is set to 1, then the textures
will not be cached to disk and will be converted in
memory.  If you are running the game under Windows 95,
then this setting is not recommended. If you are
running the game under DOS, then this setting may help
out because disk I/O access is slower on some
DOS machines than others.  The default setting is 0.
e.g. set BUILD_CONVTEXTURES=1

The BUILD_TRICOUNT environment variable shows the number
of triangles drawn in the last frame.  The default setting
is 0.
e.g. set BUILD_TRICOUNT=1

The BUILD_FPS environment variable shows the current clock
settings, frame number, and a (rough)FPS count.  
The default setting is 0. 
e.g. set BUILD_FPS=1

The BUILD_VERSION environment variable shows the current
version number of the 3Dfx Version of the Build Engine
and the current version of Glide you are using below that.
The default setting is 0.
e.g set BUILD_VERSION=1

BUILD_MRED, BUILD_MGREEN, BUILD_MBLUE set the colors
of mirrors in the game respectively.  Their range is
from 0-255.  Their default settings are 200, 200, and 255
respectively (gives a blue tinge to all mirrors)
e.g. for dark blue mirrors:
   set BUILD_MRED=0
   set BUILD_MGREEN=0
   set BUILD_MBLUE=200

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When you start up Blood 3Dfx version, the 
program will begin converting the textures in the game
to the 3Dfx format.  This only needs to be done once, and
if you want to recreate the process, then delete the 
subdirectories called tx3dfx and animxxxx where xxxx will
be a number and the directory will contain .3df files.
This takes quite a while to convert so be patient :-)
See the above environment variable BUILD_RESAMPLE for
more information on this.

Note: Cranking up the intensity with BUILD_BRIGHTNESS
will cause less of the textures to be transparent, since
the level of opacity is based on their intensity.