Geforce FX might not be FULL DX 9

[3dfx]

I was very astonished when Nvidia decided to turn off the parametric surfaces (or RT-patches in the DirectX parlance) support in their GeForce3 drivers a year ago. When asked why, Nvidia officials told that the support of curved surfaces should be turned off because several game developers implemented ATI’s TruForm technology in their games and the software decided that the GeForce3 accelerators also supported the N-Patches, whereas the GPU just tried to emulate them through RT-patches causing the performance to drop dramatically. Since the higher order surfaces are not used widely these days, their support is not something the end-users can take any advantages of, we forgot about this fact shortly after it had been revealed.

The higher order surfaces are here to allow game-developers to create very complex 3D-models without using too many triangles. There are many approaches of creating HOS surfaces, however, there are only two of them on the consumer market: RT-Pathes and derivatives and N-Patches in different incarnations. RT-Patches require control points definition over a surface at the stage of creating a model. Another way to achieve complex models and environments is to utilise N-Patches and its derivatives that calculate the control points on-the-fly. Since the latter were introduced by ATI, Nvidia said that they were not going to implement this in their own chips.

What is even more interesting is that they decided not to support Displacement Mapping technology from DirectX 9.0 due to unknown reason, according to sources. Maybe because the approach is based on the notorious N-Pathes?

Microsoft wants IHVs to support Displacement Mapping and points it out in every document they issue in regards DirectX 9.0. Both ATI Technologies’ RADEON 9700/9500 VPUs and Matrox Graphics’ Parhelia 512 graphics processor support the Displacement Mapping.

I now wonder if Displacement Mapping is “must be” function of the DirectX 9.0. If it is, Nvidia may not be able to claim the DirectX 9.0 full hardware support for the GeForce FX VPU.

[GNEP]

http://www.beyond3d.com/forum/viewtopic.php?t=3219

[KeiFront]

Lets add another link http://www.xbitlabs.com/news/story.html?id=1037838967

[GNEP]

If true, this could be very bad for Matrox - without nVidia's support, displacement mapping (whilst a potentially v. useful technology) would get very little support from games developers.

Shame if true.

But then no one has either full final DX9, full final DX9 drivers, or an NV30 yet. So it's all speculation at the mo.

Gnep

[3dfx]

Yes but the Radeon 9700 supports it

[DGhost]

DM is not required for a part to be DX9 compliant. it is just a part of the specification, like N-Patches was in DX8 and like bumpmapping was in DX 6/7.

this came up in another thread here.

Edit: it just goes to show that websites will do anything for hits... its not like this info is hard to come by...

[KngtRider]

Yeah everyone is pimping that story about gfx+dx9, gets a bit annoying when you see x sites mentioning it and those x number of sites each have y number of people who each think they are a guru

And there are 3 or more cards that need to be seen how well they work with DX9x yet.

Note how no one has mentioned anything or asked anything about 2D/Video/Software, and all those damm otes wannabe sample cards with blowers on em are not final versions (clockspeed and external tdms/tv encoder)

[knirfie]

i dont think Displacement Mapping will be in trouble if nVidia fails to support it, since it is DX9, ATI supports it in the 9700/9500 series, which will probably become really good sellers, when they come out at descent prices, and the best videocard to be realeased is going to support it: the Parhelia 2

[funky-d-munky]

This could become a big issue. It can go one of two ways:
1.) No game developers use DM and Ati and Matrox gain no sales because of its inclusion.
2.)DM becomes very popular and consummers demand it, Nvidia flails and we see the V5 non T&L all over again!
Whats your pick?

[DGhost]

DM might be an interesting piece of technology, but to implement properly in a game engine requires low poly meshes that are designed specifically for it. it also requires a lot of tweaking, as fine details tend to look rather bad if it doesn't subdivide the model enough, etc. It probably won't be used much until the basic, lowend video cards support it, like the GF2MX and low end ATI cards support bump mapping now. It just requires far too much design work to effectively take advantage of it for one or two video cards on the market.

especially after EMBM with the G400, i wouldn't buy a card just because it has some nifty feature that will be used...

look at where it got the G400...

[Indiana]

Besides at least one form of DM can be emulated via the Geforces shaders.

I'm no expert in DM, but apparently there are two forms of Displacement Mapping in DX9 (this info is taken from another website, so don't sue me if it is completely wrong ):
- Preimaged (Precomputed/Presampled) DM (no adaptive Tesselation)
- Sampled DM (adaptive Tessellation possible)

The Parhelia seems to be the only VPU/GPU supporting "Sampled DM" to the DX specification.
The GeForce FX does not support any DM, but can emulate "Sampled DM" via vertex shaders.
The Radeon 9700 PRO currently is only able to do "Preimaged DM", but like the GeforceFX it should be able to emulate "Sampled DM" via the shaders, additionally it supports n-patches with adaptive tesselation.

So it doesn't look as if the GF would be completely unable to do DM at all. Unfortunately I don't know which of the two DM routines is the more important / more likely to be implemented one.