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I wonder if anyone at old school Nvidia remembers if the NV1 card did quads to try to win a contract with Sega, or if the designers at Sega overtly wanted a car

I wonder if anyone at old school Nvidia remembers if the NV1 card did quads to try to win a contract with Sega, or if the designers at Sega overtly wanted a card that would do quads. My suspicion is that this must've been shitty influence from Sega. The Sega Saturn released in November 1994, with one of the most mind boggling bad hardware designs ever committed to a console. The thing had two CPUs, and unlike every console or 3d rendering machine to come later, actually rendered quads rather than tris. This is because you can more easily render lots of sprites for 2d games with quads (!!!). It was allegedly extremely difficult to program for such that its complexity stymied emulation for years after its release. I also read that Sega (which is actually a US company) had some sort of weird dynamic with its Japanese division such that the Japanese side of the company would design and ship hardware without consultation from the American side. Allegedly, the creator of Sonic the Hedgehog (Yuji Naka; who is currently in prison for securities fraud) would not pass the 3d engine used to build "Sonic Team's" first 3d game to the American team what was supposed to develop the main 3d Sonic game for the Saturn, and the main programmer for the Sonic 3d game engine in the US (Ofer Alon, who went to to found the company behind the 3d modeling software Z-brush) could not get a 3d sonic game to run on the Saturn because he tried writing the engine in the "slow" language "C", rather than 'ol fashioned assembly like Naka's team. Whelp, that was my knowledge dump on 90s Sega!

phire 2y ago
Nvidia weren't chasing Sega. The NV1 was really just an evolution of Sun's GX graphics card, which did quad-based accelerated 3D in 1989 (though no texture mapping, GX was limited to flat-shaded quads, or emulating gouraud shading with tessellation) Quads vs Triangles was kind of an open question as of 1993, when work on the NV1 started. Triangles are simpler, but Quads allow for a neat trick where you can do forwards texture mapping and get a much better approximation of perspective correct texturing, than you can with triangles. Nvidia went all in on this approach. Not only did they support 4 control point quads, but the NV1 can render 9 control point quadratic patches. These quadratic patches not only provide a really good approximation of a perspective correct textured quad, but can represent textured curved surfaces in 3d space. Quad-based approximations are much cheaper to implement in hardware than proper perspective correct texturing, which requires an expensive division operation per pixel. And the forwards texturing approach additional benefits with optimal memory access patterns for textures. The approach seems like a win in this era of limited hardware. The problem is that forwards texture mapping sucks for 3D artists. Artists are fine with quads, they still use them today, but forwards texture mapping is very inflexible. Inverse texture mapping (UV coords) allows you to simply drape a texture across a model with UV coordinates. Forwards texture mapping requires careful planning to get good results, you essentially need to draw the texture first and build your model out of textured quads. Many Sega Saturn games rely on automated conversion from inverse textured models. By 1996, you could just add a divider to your hardware and get proper perspective corrected inverse texturing, and there was no reason to do proper quad support, just split them into two triangles.
djmips 2y ago
That sounds plausible. I did a lot of work for Japanese companies in the nineties and it was quite eye opening.

phire 2y ago

Nvidia weren't chasing Sega. The NV1 was really just an evolution of Sun's GX graphics card, which did quad-based accelerated 3D in 1989 (though no texture mapping, GX was limited to flat-shaded quads, or emulating gouraud shading with tessellation) Quads vs Triangles was kind of an open question as of 1993, when work on the NV1 started. Triangles are simpler, but Quads allow for a neat trick where you can do forwards texture mapping and get a much better approximation of perspective correct texturing, than you can with triangles. Nvidia went all in on this approach. Not only did they support 4 control point quads, but the NV1 can render 9 control point quadratic patches. These quadratic patches not only provide a really good approximation of a perspective correct textured quad, but can represent textured curved surfaces in 3d space. Quad-based approximations are much cheaper to implement in hardware than proper perspective correct texturing, which requires an expensive division operation per pixel. And the forwards texturing approach additional benefits with optimal memory access patterns for textures. The approach seems like a win in this era of limited hardware. The problem is that forwards texture mapping sucks for 3D artists. Artists are fine with quads, they still use them today, but forwards texture mapping is very inflexible. Inverse texture mapping (UV coords) allows you to simply drape a texture across a model with UV coordinates. Forwards texture mapping requires careful planning to get good results, you essentially need to draw the texture first and build your model out of textured quads. Many Sega Saturn games rely on automated conversion from inverse textured models. By 1996, you could just add a divider to your hardware and get proper perspective corrected inverse texturing, and there was no reason to do proper quad support, just split them into two triangles.

djmips 2y ago

That sounds plausible. I did a lot of work for Japanese companies in the nineties and it was quite eye opening.