How can one find a certain hex value in an N64 game?

nintendo_nerd · Post by **nintendo_nerd** » Thu May 28, 2009 2:42 am

Okay, so, I want to find a way to modify character/boss sizes in Castlevania LOD by using a program called LemAsm (I know, it's old, but I haven't been able to find anything good with google). There is a hex edit mode, and what I want to know is, how is one supposed to find what value(s) you need to change? Is there a better program or way to do this?

Palin · Post by **Palin** » Thu May 28, 2009 5:39 am

From my rudimentary understanding of the concept, you record the values before you take an action, then after the action you record what hex has changed. For example, take a copy of the hex before and after you hit a boss and compare which values changed to identify which value is associated with its hitpoints total.

The rest is just trial and error.

nintendo_nerd · Post by **nintendo_nerd** » Thu May 28, 2009 5:47 am

What I mean is, how could one change the size of an enemy in that game; would that be too hard to do?

I.S.T. · Post by **I.S.T.** » Thu May 28, 2009 6:22 am

Oh, that's something entirely different.

You'll need to extract the 3D model of the enemy you want to resize in the game and alter it with a 3D modeling program.

PHoNyMiKe · Post by **PHoNyMiKe** » Thu May 28, 2009 8:45 am

you would need to learn a bit about n64 hardware and programming. google it, find something like this or better. read the cpu and memory mapping portions. I'm sure some n64 emus have memory viewers and can log to an output file. use one, start logging code from when a boss is not on screen, and hopefully not even in memory yet. then move to the point where he gets loaded into memory, or worst case on screen. then you can stop logging. read through the asm output (it would look like this if it were snes asm, look about halfway down for some cheaply commented code), and figure out how the model was loaded to memory from the cartridge (good luck). convert those memory locations to physical file locations. then you can use lemasm to change whatever you can figure out. yeah I know "not gonna happen" right. maybe start simpler like changing the "MARIO" in the nes game to "NERD".

nintendo_nerd · Post by **nintendo_nerd** » Thu May 28, 2009 2:49 pm

I.S.T. wrote:Oh, that's something entirely different.

You'll need to extract the 3D model of the enemy you want to resize in the game and alter it with a 3D modeling program.

Do they even have one for N64 games?

I.S.T. · Post by **I.S.T.** » Thu May 28, 2009 3:02 pm

I am afraid my knowledge runs thin here. I'm not sure if a generic modeling program would work, or if you'd need a specialized one.

Look up N64 hacking, you'll find the answers you need.

gllt · Post by **gllt** » Thu May 28, 2009 7:28 pm

Perhaps ask the guys/gals that made toad's tool.

nintendo_nerd · Post by **nintendo_nerd** » Thu May 28, 2009 7:49 pm

Would it be a similar process like those hackers that made the Super Smash Bros Brawl cheat codes for the Ocarina cheat software? I thought they just pinpointed the hex values and experimented with them until the found the the ones for 0.5, 1.0 1.5.....4.0 size variables. Or did they do it some other way?

Palin · Post by **Palin** » Thu May 28, 2009 8:17 pm

In that case I'm assuming that the game already had a "scale" variable that changed the way the renderer worked.

nintendo_nerd · Post by **nintendo_nerd** » Thu May 28, 2009 8:49 pm

Hmm...like when a character touches a poison or normal mushroom? Crud, this sounds harder than it seems. Aren't there guides on how to experiment/extract Castlevania LOD models?

Post by **grinvader** » Fri May 29, 2009 12:41 am

To add onto phonymike's post, N64 games upload custom video operations to the n64 hardware.

You have to get used to the custom functions used in the game itself to know what variable means what on the actual video output.
Only then the the debugger log will actually mean something.

nintendo_nerd · Post by **nintendo_nerd** » Fri May 29, 2009 1:08 am

Are there any programs out there that can help with find out what goes to what? What kind of debugger would I need? Or rather, do any of these tools exist on romhacking.net and/or zophar.net (or related)? Hmmm...getting used to those custom functions will take time to get used to like you just said. Another challenge for me to face....

Post by **grinvader** » Fri May 29, 2009 9:01 pm

Your best bet is to get in touch with the 64 emu scene.

nintendo_nerd · Post by **nintendo_nerd** » Fri May 29, 2009 9:44 pm

Alright, I'll check out places like emuxhaven or something like that....

creaothceann · Post by **creaothceann** » Fri May 29, 2009 10:25 pm

Or RHDN.

nintendo_nerd · Post by **nintendo_nerd** » Fri May 29, 2009 11:46 pm

All I saw on RHDN were game specific utilities for these.
So, there you have it. I wish there was a way to see the hex values and change them.

franpa · Post by **franpa** » Sat May 30, 2009 1:41 am

Yes, but there forum might have an active n64 section that discusses more then what is on the website.

Post by **grinvader** » Sat May 30, 2009 2:42 pm

You also want to have a look at the documentation instead of plain utilities.
Especially when there's a document for exactly what you want to do (for SM64, so you only have to apply a similar recipe for the castlevania custom video routines).

PHoNyMiKe · Post by **PHoNyMiKe** » Thu Jun 04, 2009 8:19 pm

http://www.youtube.com/watch?v=pcKg-ixKhoE

yeah dude, even the kids on youtube can do it.