Trying to make a very accurate SMB port to Game Maker

CKY-2K/Clay Man · Post by **CKY-2K/Clay Man** » Sat Sep 08, 2007 12:35 pm

I want to try to make a seriously accurate port of SMB into Game Maker.
The display style can't really be reproduced but the physics could.

I'm gonna try to use the disassembly for a source of alot of the variables and all.

Zepper · Post by **Zepper** » Sat Sep 08, 2007 3:04 pm

Considerating someone did it using Flash, good luck. ^_^;;

CKY-2K/Clay Man · Post by **CKY-2K/Clay Man** » Wed Sep 12, 2007 10:29 am

Ok, first off I'm gonna need to know how NES calculates values to place them in effect, especially for moving things.

Game maker's movement runs by a variable called "speed".

1 speed = 1 pixel movement per step/frame/clock cycle.
Mario's walk speed is like 18, but I know he doesn't move at 18 pixels per frame.

I need to kinda pick up on how or where in the ASM does it apply this value into mario's speed.

Post by **tepples** » Wed Sep 12, 2007 11:50 am

It's likely that the game uses "fixed point", where each speed is a fraction with a constant denominator. Can speeds in Game Maker be floating-point, or fraction, or decimal?

CKY-2K/Clay Man · Post by **CKY-2K/Clay Man** » Wed Sep 12, 2007 12:00 pm

yeah fraction and decimal.
as in .2 or 1/5
what would a float point be?

It would be easier if FCEU XD had a frame-by-frame option.

After examination it seems like speed 0f = 15 pixel movements out of 16 frames.

so the speed would be 15/16.

It does used fix points.

CKY-2K/Clay Man · Post by **CKY-2K/Clay Man** » Wed Sep 12, 2007 2:27 pm

Sorry to doublepost but I made a compilation of the project of how it is so far. Check it out:

http://www.box.net/shared/rpym327g18

blargg · Post by **blargg** » Wed Sep 12, 2007 4:00 pm

No way you're going to get exact Mario physics unless you manually manage calculations. Any pre-supplied velocity or whatever will surely not offer enough control to do it.

CKY-2K/Clay Man · Post by **CKY-2K/Clay Man** » Wed Sep 12, 2007 4:37 pm

What I really need to know is how it applies values.

Zepper · Post by **Zepper** » Thu Sep 13, 2007 2:58 pm

Wiki is your friend... ^_^

http://en.wikipedia.org/wiki/Floating_point

tokumaru · Post by **tokumaru** » Thu Sep 13, 2007 7:04 pm

I doubt you will achieve a "seriously accurate port" like this.

CKY-2K/Clay Man · Post by **CKY-2K/Clay Man** » Sun Nov 11, 2007 7:18 pm

This project is out.
But I did manage to make a nice port of Donkey Kong.