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How 3D works on the 3DO... ?

Started by gameblabla, January 27, 2017, 10:11:29 PM

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gameblabla

For a long time, i was wondering how the heck can you do 3D on the 3DO...
Looking at the documentation, everything seemed to imply that the CEL Engine inside the 3DO was 2D hardware, rather than 3D...
I saw absolutely no references to it supporting polygons in hardware.
At first, i thought that all 3D games were software-rendered but the documentation seems to imply framebuffer access is very slow
so it can't be that.

Then i saw this video on the Sega Saturn (turn on subtitles, he's taiwanese) :


This video talks on why the Saturn is incapable of 3D transparencies :
At some point, he explains that the reason why the Saturn is using quadrilaterals rather than triangles for 3D was due to its sprite architecture.
He also explained that the 3D polygons are in fact, distorted sprites.

The 3DO is also using quadrilaterals and its CEL engine is also capable to distorting sprites (scaling, transparency...) just like the Sega Saturn.
Reminder : A CEL is basically some kind of a sprite that can be distorted/modified.
They also supports paletted textures and unlike the Sega Saturn, full transparency.

So 3D games on the 3DO are most likely using distorted CELs in order to create the illusion of 3D.
When you look at other consoles of the era, you can now finally understand why the PS1 was a revolution :
it was the only piece of hardware that was capable of rendering polygons with dedicated hardware without weird tricks,
other than using affine texturing and lacking perspective-correction of course.

So 3DO and Saturn were using distorted sprites/CELs and the Sega 32X was just a dumb framebuffer with two powerful CPUs...
Amiga CD32, FM Towns Marty, PC-FX, Virtual Boy : all of them had no 3D hardware and had to be entirely CPU-rendered.
The only other console with special 3D hardware was the Atari Jaguar :
its "Tom" chip had some instructions for 3D graphics but it's just more powerful than a SuperFX chip...

I'm not entirely sure though... but since it seems that the 3DO is mostly 2D hardware at heart,
it is the only way to achieve 3D graphics at acceptable speed.
  • Calculators owned: None (used to own an Nspire and TI-89)

Dream of Omnimaga

Interesting. This surprises me considering 3D games for the 3DO seemed to run at quite smooth speed and still have good graphics for its time. They were more simple than PS1 games but at least not as choppy as some 32X and Atari Jaguar games. I mean, on the Jaguar, that Wheredidyoulearntoflywheredidyoulearntoflywheredidyoulearntoflywheredidyoulearntofly game basically looked like Star Fox for the SNES with only a few extra FPS.
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Yuki

I remember LGR talked about it a bit when he reviewed a graphic card that could run Sega Saturn games. Basically, at the time, with low polygon counts, using quads was better than using triangles.

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gameblabla

Quote from: DJ Omnimaga on January 28, 2017, 05:58:22 AM
Interesting. This surprises me considering 3D games for the 3DO seemed to run at quite smooth speed and still have good graphics for its time.
Me too. When i made my first 3DO game Vigoroth the delivery man (now available on Gameblabla's Crappy compilation),
i was surprised by how fast the CEL engine was if handled properly. I dare to say it's better than the Sega Saturn as far graphics goes.
CELs are also much faster if very small, which helps a lot for 3D as the distorted sprites are usually very small.
It's not surprising to see that 3DO games often have faster 3D graphics than the Saturn.
In fact, the reason why Doom is so slow on the 3DO is because it is software-rendered and framebuffer speed on the 3DO is atrocious,
especially with the weak main cpu.

Quote from: Juju on January 28, 2017, 06:53:43 AM
I remember LGR talked about it a bit when he reviewed a graphic card that could run Sega Saturn games. Basically, at the time, with low polygon counts, using quads was better than using triangles.
Yeah, the NV1 card lol... It was terrible but Nvidia learned from their mistakes.
Another piece of history about this card : MechWarrior 2 was originally planning to support that card for 3D acceleration.
However, the quad-based card was causing them a lot of trouble for development.
It also was slower than cards like the Voodoo.
In the end, they dropped support for it. But what happened next was unusual :
Nvidia wanting to know why they struggled so much to support it, came to Mechwarrior's devs and asked them
how they could improve their graphics card.
It's unusual because most graphic card makers at the time did not give a single c of how games were performing on their cards.
This eventually led to the Nvidia TNT video card, which was much better than the NV1.

And this has absolutely nothing to do with the 3DO... oh well
  • Calculators owned: None (used to own an Nspire and TI-89)

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