3dfx
Voodoo 5 5500 AGP review
Posted by Thomas
McGuire on September 13, 2000
Company:
3dfx
Interactive Product: Voodoo
5 5500 AGP
You
can read the first
part of 3DS' V5 5500 review here
Post
filters
In
Part 1 of the Voodoo 5 5500 AGP review you may have noticed
me mentioning the use of post filters to achieve near 32-bit
image quality, with near 16-bit performance. In the 3dfx
Advanced Features tab 2 options are available for both
Direct3D & OpenGL/Glide, these being Alpha Blending
& 3D Filter Quality. These options control the
following.
Alpha
Blending. This
is used to enable dither subtraction on the destination
colour during alpha blending. When dither subtraction is
enabled, the dither matrix used to convert 24-bit colour to
16-bit colour is subtracted from the destination colour
before applying the alpha-blending algorithm.
Setting
this to Automatic will allow the program to use this dither subtraction as
required. Setting it to Sharper
will enable
dither subtraction, resulting in a sharper image. Setting it
to Smoother will disable
dither subtraction, resulting in a smoother image. The Alpha
blending option is ignored when running in 32-bit colour.
3D
Filter Quality.
Using this setting you can further improve image quality. The
display image can be filtered by averaging pixel values.
Selecting
High (uses two
adjacent horizontal pixels from a line & the two pixels
on the line below (a 2x2 box filter) to create one output
pixel) will result in more pixels being averaged, resulting
in a sharper image. Selecting Normal
(uses four adjacent samples on a line (a 4x1 linear filter)
to create one output pixel) will average less pixels than High, resulting in a smoother, blurrier image. Selecting Automatic
will allow the program to use filtering as needed.
As
you may have read in Reactor
Critical’s Voodoo 5 review, there is an issue with
screen captures & utilities like Hypersnap.
Greg Kochaniak (author of Hypersnap)
had the following say regarding it;
You can
actually capture mostly correct colours from Voodoo5 with
HyperSnap-DX 3.63. I say "mostly", because I can
do only a "frame buffer" shot from that card. The
colour filter & post-processing, that I have for Voodoo
- Voodoo3 cards, was not updated so far by 3dfx to provide
even better shots from Voodoo5. I'm trying to talk them into
fixing this code, but don't know what will happen.
That
said, only OpenGL/Glide is affected by this. Direct3D
remains unaffected by this screen capture issue at all.
Here’s some screenshots to illustrate the effects of the
Post filter (NOTE – These screenshots were taken using a
special environmental variable, thanks Rev.,
& as such they are correct in there visual accuracy –
Reactor Critical’s shots aren’t entirely accurate as you
can read here,
See Kenguru’s post where he states “You
are right, I did not knew about Glide special shot key.”).
For the purposes of these shots Texture compression &
FSAA were disabled.

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