a sonic emulator and level editor, that sounds hard.

Sonic clones... I've seen so many of them
Why did you say is your Sonic Engine better than any of the others??

Well one thing is my engine is the only one to use the exact same algorithms as the original engine used to create Sonic 1, 2, and 3(&K). So will be accurate to the point where if you were to play a demo in the original games, and play the demo in this engine using the exact same level, it would play exactly the same without any issues. That's the goal. For example, he speeds up going down hill, and he slows down going up hill, and this change in speed is identical to the original games.

My engine will also use scripting to allow users to write objects and various other things for it. And if they don't understand the scripting language, I will also likely create a program that will be basically like the "event editor" in Click & Create / Multimedia Fusion (don't know if you guys know what those programs are or not). It'll basically cover up the code and give you easy point-and-click style interaction so that any dummy can write objects for their game.

Another point -- my engine will be backwards compatible with the levels and other data used in the original games. As seen in my screen shots, you have Emerald Hill which is the first level of Sonic 2. My utility "LIMP" reads the Sonic 2 ROM image and exports the level data and formats it so that it can be read by my engine. All the slope data, solidity, art, tiles, and layout is all there and fully playable through my engine. But this isn't just to play original Sonic levels. My engine allows you to design your own, up to 256 levels (unlike the 17 limit imposed on Sonic 2).

So I think it'll be very much advanced. It's basically n enhanced replica of the original engine, with more features and fewer limits (e.g. 256 colors instead of 16*4). I am also thinking of adding YM2612 (that's the Yamaha DX synthesis chip used in the Genesis/Mega-Drive) emulation to be able to reproduce Genesis music, though I'd probably only do it if there were enough people willing to use that. Either way, it'll still support MIDI, and it'll still support OGG files.

It shouldn't be to hard to get ahold of the source; I found the disassembled Metroid 1 source one time.

edit; Oops here it is...

Metriod 1 is a bit less complex than Sonic the Hedgehog.

Take at look at his blog pictures, they're pretty impressive.

Well, certainly a lot of it has to do with my ROM hacking experience, but coming up with the exact formulas was actually the result of me simply testing and looking to see how the variables change. I studied the changes, and I was able to create algorithms that did exactly what the original engine did. Whenever I come across inaccuracies, I adjust my algorithms so make them as perfect as possible.

I am more than willing to give out any of the algorithms I have figured out. For example, you have a slope value of 'n' which is 8-bits. 0 is 0 degrees, 0x40 is 270 degrees, 0x80 is 180 degrees, and so on, all the way around. So to calculate the player's X velocity, you do this:

float_value = Sin(90 / 64 * ((n + 0x40) & 0xFF))

Then round float_value to the nearest one-thousandth. Then...

float_value *= player->Speed / 6

Then truncate float_value to get rid of the decimals (or simply cast it to an integer). We'll do this by...

int_value = (int)float_value

Then simply multiply the integer by 6...

int_value *= 6

And that gives you the player's X velocity!

Oh, and I have an FAQ up on my blog now if anyone is interested. It answers some questions I've had by various people.

Looks pretty sick there. Nice framerate too.