DX9 (HL2 & Doom3) on ATI vs Nvidia

  • Thread starter Thread starter Roger Squires
  • Start date Start date
"DX9 (HL2 & Doom3) on ATI vs Nvidia"

Doom3 is OpenGL not DirectX.
 
Roger said:
Good article here:
http://www.gamersdepot.com/hardware/video_cards/ati_vs_nvidia/dx9_desktop/001.htm
Nvidia is hurting and will have to lower IQ again to compete.
Click to expand...

John Carmack on Doom3 and NV30 vs R300:

http://www.beyond3d.com/interviews/jcnv30r300/index.php?p=1

An interesting read.


Note

R350 Pixel shader program length is "unlimited" on the R350, a significant
improvement from 160 on the R300 - this is the limitation John Carmack
mentions in the above article.

R350 Vertex shaders have been increased to 65280 instructions from 1024
instructions on the R300, both with flow control

Reference here:

http://www.ati.com/companyinfo/glossary/includes/list.html#smartshader20



NV35 Pixel shaders are limited to 1024 instructions

NV35 Vertex shaders are limited to 65536 instructions again, with flow
control.

http://www.nvidia.com/attach/4099?type=support&primitive=0


So there.

:-)

Ben
 
Interesting read, were you aware that Splinter Cell doesn't actually support
AA? It also makes the game go "wonky" as in not run properly with AA
switched on...
Click to expand...

The "wonkyness" issue with SS is the exact same as the one people were
yelling and screaming so much about regarding half-life 2. The game packs
several different textures into one, so on some polygon angles the texturing
hardware will read texels belonging to a different sub-texture when using
multisample antialiasing. That's what causes the "wonkyness". It can be
circumvented using various techniques, the simplest one being the driver
silently just ignoring your setting to force AA on...
 
R350 Pixel shader program length is "unlimited" on the R350, a significant
improvement from 160 on the R300 - this is the limitation John Carmack
mentions in the above article.
Click to expand...

Except, Doom3 will have NO problems whatsoever even with a 160 instruction
pixel shader. If a game used 160 instruction shaders throughout on every
single polygon, it would run so slow it wouldn't be playable at all. 1024
instruction shaders of NV30 just makes things much Much MUCH worse of course
(especially coupled with NV3x architecture's inherently lower shader
execution speed).
 
The "wonkyness" issue with SS is the exact same as the one people were
yelling and screaming so much about regarding half-life 2.
Click to expand...

They why does the effect happen on both ATI and NVidia hardware? The
HL2 problem was supposed to be NVidia specific.
 
Lenny said:
Except, Doom3 will have NO problems whatsoever even with a 160
instruction pixel shader. If a game used 160 instruction shaders
throughout on every single polygon, it would run so slow it wouldn't
be playable at all. 1024 instruction shaders of NV30 just makes
things much Much MUCH worse of course (especially coupled with NV3x
architecture's inherently lower shader execution speed).
Click to expand...

Indeed, I'm sure that you can produce some pretty amazing effects with 1024
or even "unlimited" instructions, but then, you can probably produce some
pretty amazing effects with 100 instructions and you'd probably be hard
pushed to tell the difference if done correctly.

I haven't looked into the details of pixel shaders so I don't really know
what sort of instruction sets are available.

DX9.0 specifies 192 instructions for Pixel Shaders - I can't imagine DX10
specifying more than 1024, but who knows.

Ben
 
At the end of the day its not about the hardware but the driver support.
I have been plagued by ATI driver issues in the past and have found Nvidia
drivers to be spot on but if you ask me (which you didn't) 3DFX were always
No.1 until of course, Nvidia bought them up and binned them.
I use Nvidia hardware but I will never forgive them :-)

Jaymeister

N.B My old Voodoo 3 is still kicking ass on my kids
computer........................the legend lives on !!!
 
Jaymeister said:
At the end of the day its not about the hardware but the driver
support.
I have been plagued by ATI driver issues in the past and have found
Click to expand...

Pre-Catalyst? Things have changed...
Nvidia drivers to be spot on but if you ask me (which you didn't)
3DFX were always
No.1 until of course, Nvidia bought them up and binned them.
I use Nvidia hardware but I will never forgive them :-)
Click to expand...

Hehe, 3DFX had some good programmers...

Ben
 
Interesting read, were you aware that Splinter Cell doesn't actually
support
Click to expand...
The "wonkyness" issue with SS is the exact same as the one people were
yelling and screaming so much about regarding half-life 2. The game
Click to expand...

I've encountered several games with a GF4 that didn't it when FSAA was
enabled. In each case switching from multisampling to supersamlping (via
aTuner) caused all of the wonkiness to go away. Surely the ATI cards also
support some form of pure supersampling?
 
tq96 said:
I've encountered several games with a GF4 that didn't it when FSAA was
enabled. In each case switching from multisampling to supersamlping
(via aTuner) caused all of the wonkiness to go away. Surely the ATI
cards also support some form of pure supersampling?
Click to expand...

Yeah - it's called running at a higher resolution :-)

:-)

There doesn't appear to be an option in the control panel.

Ben
 
(via aTuner) caused all of the wonkiness to go away. Surely the ATI
Yeah - it's called running at a higher resolution :-)
Click to expand...

That's always an option, unless you're using TV-Out. The standard
definition of a television is very close to 640x480 and applying 4x
supersampling on top of that makes a world of difference.
 
That's always an option, unless you're using TV-Out. The standard
definition of a television is very close to 640x480
Click to expand...

Actually, as the TV signal is analog means it doesn't have discrete pixels,
only lines. A TV tube's resolution is usually enough to squeeze in at least
1000 pixels if a computer display is used as an input. Your mileage may
vary - greatly - depending on things like how big the borders are on that
particular TV set is (the cheaper the set the bigger the borders, generally
speaking), and the pixel clock of the graphic card doing the output (the
faster, the smaller the actual width of the image, so less information will
be lost on the edges of the TV screen).
 
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