Analyzing ram Bart vs space mutants

You can talk about almost anything that you want to on this board.

Moderator: Moderators

Post Reply
shao82
Posts: 3
Joined: Sat Jan 16, 2021 11:07 am

Analyzing ram Bart vs space mutants

Post by shao82 » Sat Jan 16, 2021 11:09 am

Hi, I'm trying to reproduce Bart's move in NES Space mutants in my game engine.
I am looking at RAM values with Mesen.
I think these 3 values are quite important for the speed and acceleration of the character.
For example, I believe that the maximum speed of the character is 64 pixels per second but I have not been able to corroborate it.
Does anyone around here know anything about this or is there a tool that can help me in any way?
Attachments
1.png
1.png (25.53 KiB) Viewed 2310 times

User avatar
DRW
Posts: 2050
Joined: Sat Sep 07, 2013 2:59 pm

Re: Analyzing ram Bart vs space mutants

Post by DRW » Sat Jan 16, 2021 11:47 am

Simple suggestion: Why don't you record a gameplay video, play it frame by frame, make screenshots and simply count the pixels that he's walking.
My game "City Trouble": www.denny-r-walter.de/city.htm

shao82
Posts: 3
Joined: Sat Jan 16, 2021 11:07 am

Re: Analyzing ram Bart vs space mutants

Post by shao82 » Sun Jan 17, 2021 2:33 am

I thought that this would be the most accurate way to know the necessary values but it is difficult to decipher the operation and the forces that are exerted on the character.
I will record video to see what I can get.

User avatar
tokumaru
Posts: 12003
Joined: Sat Feb 12, 2005 9:43 pm
Location: Rio de Janeiro - Brazil

Re: Analyzing ram Bart vs space mutants

Post by tokumaru » Sun Jan 17, 2021 4:50 am

Looking at the original code is indeed the most accurate way to replicate a game's physics, but actually locating every value you need in ROM/RAM and reverse engineering the code that uses them could take a lot of time, which you might not have or not want to spend on this. Being the first to do this kind of research for a particular game can be pretty time-consuming.

I have used the video approach before, and the results were pretty good. I open the videos in Photoshop, where I can create a new layer on top of them and draw markers to keep track of where things are/were, making the process of counting pixels pretty simple. Depending on how complex the physics engine is this might not work so well, but I wouldn't expect anything particularly complex from a Simpsons game on the NES.

shao82
Posts: 3
Joined: Sat Jan 16, 2021 11:07 am

Re: Analyzing ram Bart vs space mutants

Post by shao82 » Sun Jan 24, 2021 2:47 pm

Yes, the goal can be reached in two ways:
-Analyzing the code and RAM values (Mesen is a good way), for this you should perhaps learn assembler (6502) to understand the execution of the code and the movement of the values. With this you will achieve maximum precision in the code you intend to replicate.

-Use recorded video and analyze frame by frame, you can get a result very close to the original but it will not be perfect.

It depends on what you want to achieve, you can use one method or another.

Post Reply