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Old 08 April 2019, 15:59   #1
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Join Date: Nov 2015
Location: Vaasa, Finland
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SNES SF2 Dual PF Demo

Okay, so here is another AGA Street Fighter 2 tech demo. Originally I didn't plan to release this until it was "ready", meaning that there would be some real gameplay. But as usual, I ran out of motivation, and so the project has been sitting on my hard drive since 2017. And because in all likehood I'll never continue it, I thought that I might as well post it here, because people are once again talking about how to properly convert SF2 to Amiga, and at least this demo theoretically demostrates that one could do SF2 in AGA at 50 FPS, with background anims and parallax layers.

ADF with Blitz source code is in the attachment of this post.

So, system requirement is basic A1200 with 2 MB of Chip RAM. You can scroll the screen with the joystick.

All graphics are from the SNES version of Super SF2, because the size of the SNES characters are perfect for the AGA sprites.

Technical info:

- 64 pixel wide AGA sprites for the characters, so 4 characters can be drawn without any slowdown.

- 3 parallax layers.

- Game runs in 16+16 color dual playfield background, so this way we get two parallax layers.

- Third parallax layer is created using copper effects (sky and sea) and blitted objects to the back playfield (the mountain and the island in the horizon) .

- Characters are 100% sprites, so Blitter is 100% dedicated into drawing background animations only.

All background anims are "Blocks" with no transparency, and they are drawn to pixel positions that are multiples of 16. This makes them super fast to draw. And the lack of transparency doesn't matter, because the Back Playfield always "shines through" the color 0 pixels of the Front PF. So this way we get free transparency.

Also every Block draw automatically "clears" the block that was drawn to that spot previously, so there is no need for "background restore" or anything like that.

And finally some coppers were added to the Front playfield: the light greens of the stone ground are copper generated, and so are some of the palm tree colors on the top.

And all of this still easily runs at 50 FPS on a standard A1200. About half of the frame time still remains.


Also here are some character recolors that I did for the SNES Super SF2:

In the SNES version every character has an unique 16 color palette, which add up to 212 colors for all characters. But I managed to convert them all to a single 16 color palette, without any noticeable quality loss.

So in theory, a very nice looking AGA conversion could be done, which would be graphically almost identical to the SNES version, if not even better, and it would run at 50 FPS.

And memory wise too this is possible, all frames in both directions for two characters take about 1,2 Megs, so it's just an issue of fitting rest of the stuff into 800 kb, which should be totally possible.


However, like I have said before, a project like this is a massive undertaking, and it is unlikely that a full conversion will ever be done.

Only a small one level demo with some of the moves and some kind of simple AI opponent is realistically possible. But even something simple like this will take lots of time to accomplish.

Graphical demos like this are realtively fast and fun to make, but when it comes to actual game coding, things suddenly get slow, hard and boring.

This is also why I decided to release this demo; I got bored in programming actual gameplay, and was left with a useless Graphics demo. And back then I thought that later I would continue it, but clearly that isn't going to happen.

So here it is, at least the concept is interesting, and hopefully the stuff in the source code is useful for someone. As always, you can freely use the code in your own projects, or even continue this project, if you want.
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