November 18, 2018
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ATI Technologies
Release Date

ATI Radeon 8500
August 14, 2001 | Michael Eilers

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Diagram of TruForm Technology

Ah yes, I saved the most interesting feature of this card for last. While the whiz-bang visual effects such as pixel and vertex shading will certainly mean the games of the future will look more stunning than ever, the current 3D cards do little for games of the past besides run them at a higher resolution. ATI obviously recognized that the amazing feature set of the 8500 (and the GeForce 3) will only be truly realized six months to a year from now, when games that actually use the advanced features are released. Thus, they came up with Truform – a way to increase the visual quality of all the 3D games you already own.

This one is complex to explain, so hold on for a bumpy ride. All 3D models on the screen are composed of triangles linked together to give the illusion of solid shapes and continuous surfaces. Each triangle (or polygon) has three coordinates and three “normals” which determine both its position in the scene and how it fits against the other polygons it is attached to. These polygons are known as single-order surfaces, or surfaces made of straight lines.

DirectX 8.0 contains a method for taking a flat polygon and deriving a curved surface from it, known as N-patching. Truform is the practical application of this technology, which will allow a simple, blocky surface to be transformed into a smooth, continuous curve entirely within the card hardware – literally adding more polygons to any game model to allow for more accurate texturing and lighting effects.

The way this is accomplished is deceptively simple: the three vertexes of the polygon are averaged with the three “normals” that define the polygon’s position to create a “spline” surface which is based on curved rather than straight lines. Previously game designers “faked” curved surfaces by packing in lots of polygons together to create a blended effect, but Truform will create genuine curves (known as high-order surfaces) out of what were previously flat surfaces.

The sum total of this effect will be old games that look new again, literally – imagine the blocky, 200-polygon models of Quake suddenly looking as if they were crafted from thousands of polygons apiece, or Lara Croft’s coltish legs rendered with photo realistic curves. And the best part is that this virtual enhancement of the polygon detail in a 3D scene comes for “free” – there is virtually no performance hit, period, because the processing takes place entirely within the GPU. Not only is the smoothness of the model’s silhouette improved, but also lighting effects on the model itself should be dramatically improved.

Furthermore Truform integrates with Smoothvision and Smartshader, meaning that it can have a role in future games as well. Game designers could literally create low-poly models on purpose, knowing that Truform would enhance them on-the-fly and thus eliminate huge amounts of data that previously had to be passed over the AGP bus to the card.

Now don’t pop the cork on the champagne just yet – Truform does require past games to be patched in order to add support. However ATI assured us that this patch was in most cases just a single line of code, and furthermore they have industry-wide support from current game developers that future games will ship with Truform enabled by default. Truform may very well be the “killer app” that ATI will need to differentiate itself from NVIDIA’s offerings in this cutthroat marketplace.


Archives  Previews  ATI Radeon 8500