Trying to understand this specific boss jump movement code for my NES romhack

Started by Timaeus, January 12, 2023, 03:47:36 PM

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  The game in question is Megaman 1.

  Basically, I want to make a robot master of mine be able to jump and land exactly where Megaman is, on Megaman's X position, which is horizontal.

  I came up with alot of information about some things that could help, and right now, I did managed to make it work, but only with a very low jump Height. The logic that I came out was: set sprite id, set animation related command, set jump height whole value as 6, set jump height fractionated value as 20, set the carry to 1, load Megaman's X position, subtract with the boss's X position, add the whole value to the jump distance whole command and the remainder (in the carry, probably) as the value of the jump distance fractionated command, call a function to make the boss jump at the direction that I am (left or right), move to the next boss code, end (rts)

  Obs: the fractionated commands goes from 00 to FF (0 to 255), and the whole commands goes uses 256 as a base for the value (which means value 01 makes it move 1 pixel per frame, representing 256. Value 2 represents 512, etc.)

  Is this logic correct? If not, I want to know what I did wrong on it, because I want to understand these things better to improve my coding skill.

Do little by little, one thing at a time, and never forget why you do what it should be done!


Sounds about right.

Is there a reason you're describing your code instead of actually posting it?

Instead of fractionated and whole commands, better call them low and high bytes.



  So that is what high and low numbers are about in this kind of language. Thanks for that.

  I did not had the code in hex when I did the post. Sorry about that.

  It turned out that I had to subtract the boss X position's with Megaman's, and then do some stuff until it reaches the part of doing a division of the result by the number of frames that the jump takes from start to finish (with a specific jump height). Then add high values into a specific high value command and the remainder of the division in a low value command.

  The hardest part was finding out how to handle the remainder value, but I finally managed to make the whole thing work.

  Thank you, dude. :)
Do little by little, one thing at a time, and never forget why you do what it should be done!