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.