News: 11 March 2016 - Forum Rules
Current Moderators - DarkSol, KingMike, MathOnNapkins, Azkadellia, Danke

Author Topic: [Help with graphic editing] Classic NES Mega Man / Rockman  (Read 291 times)

rurouni30

  • Jr. Member
  • **
  • Posts: 5
    • View Profile
[Help with graphic editing] Classic NES Mega Man / Rockman
« on: October 23, 2020, 12:09:59 pm »
Hello guys, I'm very new in this area of editing scripts and mods for roms yet.

Although I have seen several tutorials spread across the web and in the community itself besides having succeeded in editing some specific graphic points and editing text in hexidecimal... I'm still having some difficulty understanding how I can edit the American roms of mega man games to leave them with the Japanese-style login screen. I usually learn better by watching videos than reading, but I haven't found any that could actually help me.

My intention for this is precisely to leave the classic mega man games with the Japanese style in the design and text of the speeches (correcting subtle errors of interpretation of the American capcom). But I find myself in this situation that is blocking my project to share with the community.

Basically what I was trying to do was simply copy and paste replacing the graphics sprites using the "Tile Layer Pro". It certainly shouldn't be like that making that kind of change, or maybe I'm actually doing something wrong and not knowing what.

On the left side of the image is the American rom and on the right side the rom in the Japanese version of the title screen.



And in the image below an example of what it looks like if I do it this wrong way.



The roms I'm trying to edit first and found this difficulty were those of games 4, 3 and 2.

If I can understand how to do this later the idea is to post in the community layout/design versions for the mega man 1 - 6 respectively. To then venture to change the other of the classic room 7 - 10.

I apologize for any inthis need and thank you for having read so far and can humbly help me with this doubt.

tygerbug

  • Jr. Member
  • **
  • Posts: 59
    • View Profile
Re: [Help with graphic editing] Classic NES Mega Man / Rockman
« Reply #1 on: October 23, 2020, 02:27:18 pm »
Your Japanese graphics are not laid out in the same positions as the American graphics are. Note the position of the helmet, of the text, and whatnot.

You could move them around to match what the American graphics are doing, or vice versa.


You can also modify nametables in NES Screen Tool, and then use that as reference to change the code in the ROM.

Here's a previous tutorial:


Export your nametable for any scene from the Mesen emulator's Memory Tools.



Here I am looking at Nametable RAM, including what looks like the palettes at bottom. Save the nametable RAM as a file.

Open this up in a hex editor. It's twice as big as it should be. Delete the second half of the file from 400 onward. Rename to .NAM.

Import CHR graphics into shiru's NES Screen Tool, by importing the NES file and selecting a CHR bank.

Open your NAM file.

https://shiru.untergrund.net/software.shtml

Recreate your palettes manually I guess.

At this point you can alter your background sprites and palettes, and save the results to be copy/pasted back into the ROM later. You can also create onscreen sprite displays as a metasprite bank.

You can use NES Screen Tool like a drawing tool here, placing tiles and palettes. Check or uncheck "Apply Tiles" and "Apply Palettes."

The .bin data you save when you're done can be manually reinserted into your NES ROM in the appropriate places.



   In Mesen (or in your old DMP file), copy a few bytes/numbers from the unaltered nametable and search for THAT in the NES file.

  Find this data inside the original ROM in a hex editor.

  (Either in a Hex editor or in FCEUX's Hex editor. Open up Debug/Hex editor/ROM file, you will be able to see your changes in real time. I suppose Mesen can do this too.)

  You have found the Nametable for this scene inside the ROM.

  You may be able to simply copy/paste your new/altered Nametable info directly into the ROM (from the .BIN file you exported from NES Screen Tool, or from an .MSB if you were working with sprites).

   However, the code in the actual ROM may be different and more complex than that - there may be extra commands which jump around the screen, like maybe a three-byte command on every line break, or commands which seek to a specific point onscreen.

   So you may need to make changes to your code to account for that.. Compare your new code to the old hex code.

   Try this in FCEUX's hex editor, while working with the CHR ROM. See if you're breaking the code by pasting in the new code.

  (It depends on the ROM!

  They often have some extra code which you have to work around, in the actual Nametables.

  Maybe an extra three bytes before every line of sprites, and an extra three bytes in the middle of the color palette at the end.

  It's not too hard though! Just something to look out for, and add to your new code!)
« Last Edit: October 23, 2020, 02:38:28 pm by tygerbug »

rurouni30

  • Jr. Member
  • **
  • Posts: 5
    • View Profile
Re: [Help with graphic editing] Classic NES Mega Man / Rockman
« Reply #2 on: October 23, 2020, 06:01:00 pm »
tygerbug thank you very much for your explanation details and helps my friend. I confess that I still found a little complicated, but I believe that after I do a reading again and see some videos about this tool I can already give the first step in this project. :thumbsup: