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Old 17 December 2015, 05:21   #96
Code Kitten

Join Date: Aug 2015
Location: Montreal/Canadia
Age: 46
Posts: 1,021
Originally Posted by Galahad/FLT View Post
The fact US Gold were involved was never a good sign, thankfully Sega cancelled all the licences and decided to make Sonic their mascot.
I'm with this kitten!

Just thinking this might have happened sends cold shivers down my spine. There would have been no better way to hasten the demise of the Amiga than such an horror. The worst of all being that US Gold would very likely have made money for such a crime.

Originally Posted by Mrs Beanbag View Post
i did actually make a Green Hill Zone using the Mr Beanbag engine, it might be worth pursuing, it's funny to look at if nothing else. I converted the sprites as well, hmm, i wonder if i've got them on my PC i'll just have a look...

EDIT yes i found them
Nice! But what a tease you are.
How loudly do I need to purr for you to post a video of it in action on Youtube?

With this, let me resurrect a few old posts from this thread which deserve a clear answer:

Originally Posted by P-J View Post
My personal interest in this is to know if a 1:1 conversion was possible (assuming factors such as access to the original source, artwork and so on). So are there technical features in the Megadrive game that the seasoned coders (Galahad, StingRay et al.) could quantifiably say would not be possible, or are at least highly unlikely? And additionally, whether an AGA equipped Amiga could do it.
This is a most excellently formulated question the answer to which is: extremely unlikely to be possible on OCS (as Lady Beanbag said). If you do not want 1:1, then as Galahad said, yup, there is not a shred of doubt that a very good conversion is possible, with a downgrade.
Get rid of the parallax and the rest is easy, or keep it and sacrifice a few other things (bob colors, etc.).

AGA: again, Lady Beanbag hinted this was potentially possible and a version could get pretty close but a MegaDrive is quite powerful so it is hard to be certain.

Remember that a MegaDrive can output 320 pixels of 16 colour non repeating sprites per scanline without CPU intervention or DMA cost. Its dual playfield mode has double the colours than that of the Amiga and also comes for free without any DMA penalties. Really good games can even exhaust the sprite list mid screen and send a new one via DMA in order to draw even more sprites on screen (a-la copper). A game that really exploits well the hardware is simply impossible to convert 1:1 on OCS, and possibly doable but hard on AGA.

Originally Posted by P-J View Post
To further add to that-- I worked out that Sonic on the Master System is at it's maximum pushing 8px/frame (at 256 wide) and that seems pretty bloody fast once it's happening in front of you.
Yes, no need to modify many pixels per frame to have fast scrolling.
One only needs to scroll 320 / 50 = 6.4 pixels per frame to scroll an entire screen per second.

Sonic's maximum scrolling speed is very comfortably within the Amiga limits.

Originally Posted by P-J View Post
Ladies, please. Let's get back to the real issue which is why you're not teaming together to make a 1:1 port of Sonic as we speak.

While you watch?

Originally Posted by lordofchaos View Post
I still think a perfect conversion of sonic would and could have been possible on the Amiga but it would have been highly unlikely, we know the evidence is there, just look at the games/demos that stick a middle finger up to it`s own hardware limitations..
That a few games exhibit _some_ but not all of the features of Sonic, does not prove that it is possible to have a conversion which integrates them all. The killer is precisely to have them all together, that is where the hardware of the Amiga is not sufficient.

To your knowledge, can the Amiga OCS do all of the following at the same time?
63 colours per scanline.
15 colours per playfield per scanline.
32 colours per scanline for sprites.
320 pixels of non repeating 16 colour sprites per scanline.
CPU has full access to RAM without penalties.

Because the MD can. And Sonic makes a quite good use of these.
(The answer is "no" btw.)

I think that one or two levels of Sonic can be done very close to 1:1 with some very clever (and difficult) tricks but the others require a downscale. They will still look nice, but they won't be 1:1.

Originally Posted by lordofchaos View Post
The coding talent pool did exist to pull it off but was spread over too many different developers and demo sceners, it would have taken a massive effort to bring them all together and work on the game.
You really underestimate how capable the MD hardware is compared to the OCS chipset. No matter the talent pool, when a level requires more than 32 colours per scanline on screen with dual playfield parallax and massive number of moving objects, then the OCS Amiga just cannot do it.

Originally Posted by lordofchaos View Post
Coders have been and will continue to defy the limit that is set out in front of them. The real trouble was down to publishers and lack of real interest to develop the game on the Amiga, at the time Sega was really pushing the Mega Drive brand with Sonic and wanted to keep its IP synonymous with its own machine.
Coders did defy conventional limits (because the real limits, well, no one knows what they are, by definition) but there still are some pretty solid limits which cannot be overcome whatever the trick.

Number of colours per scanline? That's 32 or 16 maximum if you want to be able to move a lot of objects. If you want EHB's 64 you must forget moving lots of objects because each bitplane reduces the blitter speed. And if you want full screen parallax you have maximum 15 colours per scanline and the same number of bitplanes and limitations than EHB.

Great and technically impressive games on the Amiga were made because they were very carefully tailored to these limitations and CodeTapper's site does a fantastic job of explaining that. All the technically great Amiga games sacrifice a few things in order to play to the Amiga strengths.

Sonic 1:1, generally does not allow these sacrifices, it wants everything at the same time: colours per scanline, full screen parallax and many objects. In some levels (the first notably and maybe the second), there might be ways to play to the Amiga strengths by exploiting the level structure and colour scheme but the rest of the game requires drastic adaptations.

Last edited by ReadOnlyCat; 17 December 2015 at 05:26.
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