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As you may know, 3D cards are built around specific graphic chips. Names like Voodoo, PowerVR, Rendition, Rage and Virge should be familiar to you if you have an interest in 3D graphics. In this article, we chose to compare the two chips that we think will lead the competition in the next few months: the PowerVR developed jointly by NEC and Videologic, and the Voodoo chip created by 3DFx Interactive. Our goal is not to provide you with raw data about how much faster one card is versus the other, but rather to give you enough information so that you can make your own decision with some serious background in mind. A 3D card has a certain cost, and it is not cheap when you consider that it will only work with a definite range of games and/or other software. Fortunately, the number of titles supporting these 3D cards is increasing, which should really help the market to take off.
Paradoxically, this is with an analogy rather than a comparison that we will start with in this review. Enumerating what the cards have in common before describing their specificities seems the best approach. Both, PowerVR and Voodoo based cards, respectively Apocalypse 3D from Videologic and Monster 3D from Diamond Multimedia/Righteous 3D from Orchid, use a PCI bus and feature 4 Mb of memory. Additionally, they support Direct3D from Microsoft, are Plug-and-Play and come with five years of warranty. But even among these common points between the two technologies, there are still a few differences. With the PCI bus for example, although both cards will fit in without any problems (should you have a PCI slot left in your computer), the connections' configuration vary. The Voodoo-based cards will operate with 2D cards through an analog pass-through cable, which means the monitor will be connected directly to the 3D card, which itself will be linked to the video card through the analog cable mentioned above. In a different way, the PowerVR technology will pass the data to the 2D card through the PCI bus itself, thus eliminating the need of an external cable. This of course inducts the necessity of a powerful configuration (e.g. Pentium 166 or higher recommended) so that the transfer through the bus does not cause a slowdown. Of course, not all computers are built the same, and identical cards will deliver various performances depending on the numerous characteristics such as the motherboard design and number of other PCI devices (that might also use some of the bus bandwidth). To date, the second solution didn't prove that it was the best, all the contrary, it may be a slowdown factor that can only disappear at the condition you have a very fast Pentium with a well-designed PCI bus. Still the Voodoo solution is not perfect either, since it requires the 3D card to have a frame buffer which takes some memory. Speaking of memory, it is also used differently in both technologies, although the cards feature the same amount of memory. With the PowerVR, the whole memory is dedicated for the textures, but with the Voodoo chip, only half of it will be used for this purpose, the reason being that the other half is reserved for the Z-Buffer. For those unfamiliar with the Z-Buffer, it is a technique used to remove hidden surfaces from the screen. Indeed, besides being useless to draw polygons that can't be seen from your point of view, it also reduces the overall performances. With the Z-Buffering method, for each pixel on the screen is associated a depth (z) parameter that represents the current depth value of that particular pixel. This way, should new polygons be found behind previously drawn polygons, they will be ignored and not displayed on the screen. The disadvantage of this method is that it has a high memory consumption. So how does the PowerVR technology deal with the hidden surface removal procedure? Well, instead of allocating costly memory for the Z-Buffer, the PowerVR choice was to use an Image Synthesis Process (ISP) which performs the calculations at the clock speed of the main processor (60 MHz). Furthermore, it is equivalent to a 32-bit Z-buffer which is superior to the 16-bit Z-Buffer offered on the Voodoo-based accelerators.
When it comes to 3D APIs, both chips support Direct3D from Microsoft, which assures you compatibility with most recent 3D games (Hyperblade, MDK, Outlaws, WipeOut XL-USA, WipeOut 2027-Europe). But unfortunately, not all the cards behave the same with Microsoft's API, and it's not solely a question of hardware, but also of drivers. When compared with the first generation of drivers that originally shipped with the cards, the new drivers available from each manufacturer show a great amelioration that often increases the performances by 25% and even more. While not being far off from one another in the tests, the Voodoo chip had better results in our Direct3D tests than the PowerVR (with each card being tested on identical computers). The differences were not significative though. Indeed, the human eye as perfect as it surely is, can't notice the difference between 58 and 60 frames per second! In addition to the Direct3D support, each chip features support for other APIs. The Voodoo chip can also use WinGlide, Criterion Renderware, Intel 3DR and Reality Lab 2.0 APIs, while the PowerVR uses the PowerSGL, a special API that has been developed for it. As noted by many developers, Direct3D performances can drastically change from one card to another. The best performances will therefore be obtained when the game takes into account all the specifications of the card through patches or drivers. An example of this can be seen with MDK. While the Direct3D generic driver works relatively well with the game, the Glide patch that is currently in development by Shiny Entertainment should deliver even better graphics for the cards equipped with a Voodoo chip. Thus, the difficulty today is to have the developers on your side and offer them easy ways to integrate the 3D technology in their games, hence the importance of the APIs.
With yet another API (OpenGL) currently in development by 3DFx Interactive, the Voodoo chip seems ahead of the competition regarding support from the gaming community. And the list of games supporting the chip is not to prove the contrary. Among the list of newly and upcoming games, there are MDK, Outlaws, Quake, Tomb Raider, Jedi Knight, Pandemonium and more to come in the next few months. The PowerVR looks pale in comparison. With only three games offering the Extreme certification (PowerSGL only with all features enabled), and all the others being either Accelerated (Direct3D) or Enhanced (Direct3D + four advanced features), the choices left to the players are nothing but short. There are of course several Extreme titles in development for the PowerVR, as well as other Enhanced games, but by the time they will be released, there will be new games available for the Voodoo chip, which needless to say has taken a serious advance over its competitors.
In terms of hardware support, each chip has its own features that the other doesn't have such as the bi-linear filtering for the Voodoo and the lens flare for the PowerVR. But overall, each chip has similar concepts (shading, lighting, fog, anti-alias and perspective-correct texturing, and more), with whom they both deliver truly exceptional graphics at a speed that is simply awe inspiring. Fog, haze and glass appear real on the screen, pixelization disappears, the frame rate is outstanding and players can finally enjoy arcade-quality games on their PC. If you are not convinced, try out Ultimate Race from Kalisto Entertainment, one of the games packed with the Apocalypse 3D, and you will be on for a visual treat! Playing in 800 by 600 with over 25 frames per second with millions of colors on the screen is not an experience you will easily forget. It is truly something that has to be seen!
The main differences between the two technologies certainly lie in how each card answered the game developers' needs. The Voodoo chip, also the first on the market, had everything to seduce 3D programmers, but inevitably suffers from serious limitations. Graphics have to be full screen, and the resolution is limited to the SVGA mode 640 by 480. On the other hand, it supports the bi-liner filtering (which eliminates the pixelization), is slightly faster with Direct3D and offers a greater API support than the PowerVR. Still you can't play with WipeOut XL using the 800 by 600 mode included in the game, forcing you to select the other mode (640 by 480). As there are no doubts that games will further use higher resolution modes in the future, this can be a decisive limiting factor. The PowerVR is not affected by this kind of problem. In fact, resolution can be as high as 1280 by 1024 (using 256 colors). Otherwise, SVGA modes like 800 by 600 can be easily used with the PowerVR (as long as your video card has two MB of memory). Furthermore, the PowerVR benefits by a scalable architecture which means the performance will increase with faster CPU's, and is said by the company to find its limit with the equivalent of a Pentium 400 MHz. The Voodoo chip will also deliver higher performances with a faster CPU, but unlike the PowerVR, it will achieve maximum performances with a Pentium 200 MHz. Finally, another difference between the two chips is the way the rendering is done. The "infinite plane" modelling used by the PowerVR technology is particularly interesting when rendering large polygons that would normally take a large memory bandwidth. Advanced lighting effects can also be rendered much easier and with better performances than with the conventional technique based on small polygons (used by the Voodoo chip).
1997 will obviously be a crucial year for the 3D market. With the decision from NEC to invest $25 million to promote the PowerVR chip in the gaming development community, there might have been much more interest in this technology that is resolutely oriented towards the future. Already, NEC has announced a second generation of PowerVR, faster and even more powerful than the precedent, while keeping a compatibility with the ancient version. Similarly, there are rumors about 3DFx Interactive developing a second generation of the Voodoo chip as well. Only the future will tell which technology will win the battle, but for now, if you want the card with which you will have the most games to play with, I suggest you to select the Voodoo chip. But if you are patient enough, wait for the PowerVR PCX2 expected to be available this summer!
Written by Frederick Claude
|Minimum System Requirements||Pentium 100Mhz, 16Mb RAM, 2Mb DirectDraw compliant graphics controller||Pentium, 8Mb RAM, Windows 95|
|Bus Architecture||32-bit PCI local bus, PCI 2.1 interface, Plug and Play compliant||32-bit PCI local bus, PCI 2.1 interface, Plug and Play compliant|
|Driver Support||PowerSGL, Microsoft Direct3D||Microsoft Direct3D, Winglide, Reality Lab 2.0, Intel 3DR, Criterion Renderware|
|Memory Configuration||4 MB high-performance SDRAM texture memory||4 MB EDO RAM (2 MB used for frame buffer and Z-buffer, 2 MB used for texture memory|
|Chip Set||PowerVR NEC PCX1||3DFx Voodoo Graphics Controller|
|Features||Perspective-correct and anti-aliased texture mapping,
Pixel perfect hidden surface removal (equivalent to Z-Buffering 32-bit),
Real time shadows,
True logarithmic colored fog,
Translucency, Smooth shading
|Texture modulation,Perspective-correct texture mapping,|
Z-buffering (16-bit), Level-of-detail MIP mapping,
Bi-linear and advanced texture filtering,
Texture compositing and morphing,
Per-pixel alpha blending effects
|Number of colors||True Color (16 millions)||16-bit (65,5536)|
|Warranty||Five years||Five years|
Home Park Estate,
Hertfordshire, WD4 8LZ.
Websites: Videologic or PowerVR
Email: Videologic UK Sales
1001 Bayhill Drive, Suite 310,
San Bruno, CA 94066.
Email: Videologic USA Sales
Max Planck Str. 25,
Email: Videologic Germany Sales
415 Clyde Avenue, Suite 105,
Mountain View, CA 94043.
Web site: 3DFx Interactive
Email: 3DFx Interactive
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