3d Tutorial

[sparhawk]

When I watched this [ Show youtube player ] I was quite impressed with this rotating cube showing the moving graphics on each side. At first I thought that they were doing some texture mapping, and was surprised because I thought the Amiga is not fast enough for that.
After thinking about how this can be done, I thought that it might be enough to have a good 3D routine, and then stuff being shown can be projected on the cube with a view transformation.


I have also seen other demos with lots of stars coming from the Z axis and I wondered if these are real 3D calculations or just some visual tricks. In the beginning of the Enigma demo above, they also have this starfield whirling around all axis, so I assume that this are really 3D calculations.



So does anybody know a good 3D tutorial where such stuff is explained for somebody not so fluent in math?

[redblade]

Go to bombjacks site and download Amiga Real-Time 3D gfx. It was released for Atari ST and Amiga. Because you are from Germany, there should be a few tutorials available in German too (I don't know any at the top of my head).

Also the danish tutorial that some translated to English has a 3d section in the last chapters, I thought it was pablo.dk but that does not seem to be the site.
Updated to: Danish 3d tutorial translated to English

[Antiriad_UK]

Originally Posted by sparhawk

When I watched this [ Show youtube player ]
I have also seen other demos with lots of stars coming from the Z axis and I wondered if these are real 3D calculations or just some visual tricks. In the beginning of the Enigma demo above, they also have this starfield whirling around all axis, so I assume that this are really 3D calculations.

The z-axis stuff is usually just a increasing z with a perspective calculation - you can get plenty of stars just doing it realtime. There's a deep dive into the perspective calc in Planet Rock Lobster (which also rotates) in this forum somewhere (they took it to extremes with log tables )

I've no idea if the Enigma box had any cheats but I've got a filled inconvex vector version I did on the a1200 back in the 90s somewhere and I just brute forced it something like:
- Is this side of the cube showing?
- If yes, rotate and perspective on that cube side's scene
- Then set the z of all the points in that side to match the "cube"
- Rotate and perspective again for that side

So that method essentially doubles the CPU time for each cube face - but that Enigma scene is all wireframe/simple so maybe it was do-able like that too. I know you can combine multiple rotation matrices into one, so I'd imagine the guy who wrote Engima was better than my basic maths and did it like that. Does anyone on here actually know though? (it's still amazing remembering seeing that for the first time, as Virgil's hyperbased remix says...OMG IT'S ROTATING )

[sparhawk]

Originally Posted by redblade

Go to bombjacks site and download Amiga Real-Time 3D gfx. It was released for Atari ST and Amiga. Because you are from Germany, there should be a few tutorials available in German too (I don't know any at the top of my head).

No need of german tutorials. English is fine as well. Thanks!
I tried to find this book for sale, as I rather like to have a hardcopy but haven't found one so far. But instead I found that the author is keeping the book along with the source code samples on gitlab:https://gitlab.com/amigasourcecodepr...me-3d-graphics

Updated to: Danish 3d tutorial translated to English

Looks like a very useful site.

Originally Posted by Antiriad_UK

I know you can combine multiple rotation matrices into one, so I'd imagine the guy who wrote Engima was better than my basic maths and did it like that.

Yea, that's what I was thinking. I don't know the math, but I knew the theory, which doesn't help much when trying to implement stuff like that.

Does anyone on here actually know though? (it's still amazing remembering seeing that for the first time, as Virgil's hyperbased remix says...OMG IT'S ROTATING )

Would be cool if a demo coder could explain a bit how it works. That's why I also appreciate the AsmSkool videos from Photon, because it doesn't just show the flashy stuff, but also the process how to get there.

[redblade]

Originally Posted by sparhawk

No need of german tutorials. English is fine as well. Thanks!

I tried to find this book for sale, as I rather like to have a hardcopy but haven't found one so far. But instead I found that the author is keeping the book along with the source code samples on gitlab:https://gitlab.com/amigasourcecodepr...me-3d-graphics

I had a look at the code, OS Friendly, Kick31 startup code as it uses lowlevel.library to put their interrupt code in the interrupt, The danish tutorial from the 80s, swaps VBlank directly so will have problems on os2+ machines.