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DS' 3D graphical secrets revealed

The Vicarious Visions boys provide the lowdown

DS' 3D graphical secrets revealed
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DS

Those fine San Francisco days spent at the Game Developers Conference seem like world away now, but before I put a cap on my memories, there's one final thing I need to get off my chest. It sounds a bit techie, but a couple of guys from Tony Hawk's Downhill Jam creator, Vicarious Visions, gave a talk about getting the most of the DS when it comes to 3D graphics.

Now, when the cigars, stilton and port are unleashed after a long day at Pocket Gamer towers, this sort of thing is often a talking point, but we're sure it's worth sharing, too.

The first surprise of the talk was the way the DS's graphics hardware is constructed. When it comes to 2D graphics, each DS screen is powered by a more powerful version of the hardware that run the single Game Boy Advance screen. This technology allows developers to 'layer' together elements such as sprites, tiled graphics and bitmaps. The main graphical difference between the GBA and DS is the DS' additional custom 3D layer.

This 'layering' architecture is interesting, because it means that programmers like those at Vicarious Visions can't just use all the DS's graphical power any way they want to. They have to make the most out of all the available elements. You can't just drop 2D graphics and use what you've saved to bulk up the 3D graphics, for example.

When it comes to the 3D graphics layer, there is a strict theoretical limitation of 2048 polygons, or 6144 vertices (or corners), per frame. DS games run at 60 frames per second, so this gives a basic throughput of 122,800 polygons per second. In comparison, the PSP can render a maximum of 33 million polygons per second: roughly 300 times as many as the DS.

On this basis, a lot of people think the DS is an underpowered 3D gaming device. Vicarious Visions says this isn't the case however, because you don't always need to use more polygons to get a nice-looking game (and they should know, as they've made some of the best-looking DS games yet released).

For example, you can get cartoon-shading on DS games without any extra processing overhead, although you have to do a trick with the screen size.

Another technique used to get around the DS' memory restrictions is to stream textures between the cartridge ROM and the DS's RAM memory. This can take many frames to complete, however, as you're only streaming in small textures during the gap between each frame, so you have to design your level so the player can't see the textures popping into place.

It's this sort of technique that Vicarious Visions assures us they'll be using to make forthcoming games such as Spider-Man 3 and Shrek the Third look better than anything we've seen before on DS. For example, they promised their next DS graphics will include Mipmapping. We're looking forward to being wowed!

Here's some more about Vicarious Visions' games on DS.