Object Tweaking Without ASM

Yeah, so this is basically all my Object Tweaking Without ASM tutorials on StephenUK's forums combined, with all the OMGs, XDs, LOLs, and ROFLs removed.

How to Look For Object Loading Procedures:

In hexadecimal, if an object is to be spawned from another object, the compiled machine code will look something like the below example:

13 7C 00 40 00 00 33 68

That would load object 0040, which is the Moto Bug exhaust. So the format of the hex code is in a format like below:

13 7C 00 aa aa 00 33 68

That would load object aaaa. If you are programming your own object using hex, for the loading to begin another line of hex would have to be placed after the above code:

00 08 00 08 33 68 00 0C 00 0C 13 68

How To Find and Modify The Way Badniks Move:

You can search for machine code that makes badniks move inside thier code. It will look somewhat like this:

31 7C mm mm rr rr

Where mmmm is how much to move and rrrr is in what direction.

rrrr has several different values you can use that affect the direction the object you are editing moves, which are listed below:

10 = left
12 = up
14 = down
16 = right

How to Find An Offset Where Sonic Gets Hurt:

In the code of objects which hurt Sonic, you will often find a pointer to 1248C0, unless your ROM has shifted before 1248C0. 1248C0 contains the HurtSonic subroutine. If you want an object to hurt Sonic, simply place the hex line:

30 28 12 48 C0

That is a pointer to 1248C0, which contains the SonicHit subroutine.
If you want to skip this code just 4E 91 it and put an FF at the end.


How To Make An Object Invisible:

Simply place the following;

11 7C 00 28 00 1C

Tada!

Monitor Types:

The type of a certain monitor is contained in the register A0 (registers are where a game stores values other than in the RAM), and then moved to the register D0. Then the game tests what monitor type is in D0. Below is a table of monitor types possible for the game to comprehend:

01 - Eggman
02 - Sonic (1UP)
03 - Speed Sneakers
04 - Shield
05 - Invincibility
06 - 10-Ring
07 - 'S'
08 - Goggles
09 - Broken
?? - Static

So it is possible to add 245 more monitor types! Though that would certainly be an unneeded handful of code. Anyway, if the monitor is set to broken, the game is told to do nothing (except show the monitor's graphics
and mappings, of course!).

Modifying Things Monitors Do:

The 10-Ring monitor gives 10 rings (contained as the value 000A). The value moved to the RAM address $FE20 is contained at A443. You can make this monitor give up 65535 (FFFF) rings by modifying the data. Sadly, it is impossible for the ring counter to contain any value above 999 and still give unglitched results. But, anyway, let's say you wanted to make the ring counter give a shield instead of 10 rings. First of all, here are the (predictable) shield values:

00 - Off
01 = On

Just like a binary digit. The ring count (but not ring counter value) is stored in RAM at $FE20. The shield value is stored in RAM at $FE2C. You only know where the value of rings moved to $FE20 is contained and the information I just told you. How do you know what to do?

Note that A443's code moves the value to $FE20. Therefore, there must be a pointer to $FE20 in the code (or the game wouldn't know where to move the rings!). So you will find FE 20 (the pointer to $FE20) beside the ring value. Change the ring value to 0001 and the pointer to FE2C, and you've got teh ultimate shield of ringiness! *bricked*

Enough with the bad jokes, Time to go on to our next snippet of this topic:

Making Monitors Play Teh Music:

Just put a 30 3C 00 xx 4E F9 00 00 13 96 and you've got it! The variable xx represents the music number you want to play. It uses the same values as the playlists, even in S1. So, wanna test teh music? Let's make the 10-Ring monitor play the shield sound to go along with our previous hack!

The sound the 10-Ring monitor plays is contained at A474. The value is really 00B5, but the music playlist only supports values from 00 to FF (it may not seem like it, but the only reason I think the programmers cut the playlist was because they didn't want you to hear the SEGA sound in the sound test for
some reason. =P). The shield music value is AF. Change the B5 to AF, and tada! Woot woot! The ultimate shield of ringiness now playz teh ultimate shield sound of ringiness! *bricked and shot 3 times*




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END COMPILATION

EDIT: Fixed error that Heran pointed out.

 

...the fuck?

Gotta check that.

 

*slaps head* Ow. I meant to have it say to search for 13 7C 00 40 02 00 33 68.

 

XVI32 is that hex editor. =P. The 'joker hex char' is the wildcard.

 

The only bad thing I can see about XVI32 is that it uses weird offset numbers, meaning you actually have to count. *gasp*