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Author Topic: Help With Gameboy "Yoshi" Sprite Hack  (Read 2871 times)

Buddermilk

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Help With Gameboy "Yoshi" Sprite Hack
« on: May 08, 2013, 09:49:11 am »
Hello, I have been working on a sprite hack of "Yoshi" (aka "Mario &Yoshi") for the gameboy.

I'm 90% complete and have hit a brick wall  :banghead: . All the sprites were easy to rip and alter, no weird encryption, or tile format, until I reached the last set of sprites I needed to change.
Opening the rom in TileLP, at offset 3800, is a set of sprites for a game over cutscene for game mode A, that changes for every 10 eggs you clear.
There are 2 egg sprite that hatch a mushroom, fire flower, star, ghost, bomb or, fish. There's also a yoshi sprite I haven't found in game yet. All these sprites are positioned in the bottom 6 pixelsof the tile, with the bottom 2 rows of pixels going on top of the tile to the right.
Even after formatting my sprites correctly and inserting them there are still random lines and pixels either the wrong color, or out of place.
I Tried for hours to find a rhyme or reason to it, but to no avail. Any help, advice or pointers would be greatly appreciated.Thanks so much.

Mattrizzle

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Re: Help With Gameboy "Yoshi" Sprite Hack
« Reply #1 on: May 08, 2013, 10:37:10 am »
Quote
All these sprites are positioned in the bottom 6 pixelsof the tile, with the bottom 2 rows of pixels going on top of the tile to the right.
If you encounter an issue such as this, you should always try pressing the plus and minus keys to navigate forward or backward a single byte in the ROM.  Eventually, you should find an offset where the graphics look as they should. If not, some form of compression is likely involved.

Fortunately, that isn't the case here. The correct offset for the start of these tiles in Yoshi (U) [!].gb is 3853.

Buddermilk

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Re: Help With Gameboy "Yoshi" Sprite Hack
« Reply #2 on: May 08, 2013, 10:51:10 am »
If you encounter an issue such as this, you should always try pressing the plus and minus keys to navigate forward or backward a single byte in the ROM.  Eventually, you should find an offset where the graphics look as they should. If not, some form of compression is likely involved.

Fortunately, that isn't the case here. The correct offset for the start of these tiles in Yoshi (U) [!].gb is 3853.
Thank you so much! I had no idea an offset could do that, I thought they just gave u a position in the rom. So with that offset typed in i should be able to just replace the sprites? Thanx again, you just made my day, time to finish this thing!

Jorpho

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Re: Help With Gameboy "Yoshi" Sprite Hack
« Reply #3 on: May 08, 2013, 11:47:27 pm »
Opening the rom in TileLP, at offset 3800, is a set of sprites for a game over cutscene for game mode A, that changes for every 10 eggs you clear.
Whaaa?  I played the heck out of that game and I cannot recall seeing anything of the sort.  Was this disabled in the final version?
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Buddermilk

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Re: Help With Gameboy "Yoshi" Sprite Hack
« Reply #4 on: May 10, 2013, 01:39:34 pm »
It doesn't play every 10 eggs, but when you die. What hatches out of the eggs changes depending on how many eggs u cleared. The B-Mode however does give u a cutscene of Mario and yoshi eating something different every level u beat. I'm done my mod, just cleaning it up a little bit and ill be adding it on here, I would love for u guys to check it out and tell me what u think

Jorpho

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Re: Help With Gameboy "Yoshi" Sprite Hack
« Reply #5 on: May 11, 2013, 10:22:26 am »
It doesn't play every 10 eggs, but when you die. What hatches out of the eggs changes depending on how many eggs u cleared.
I'm still not sure what you mean.  I never saw anything hatching out of any eggs when I died in A-mode.  Maybe multiple versions of the game were released?
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Mattrizzle

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Re: Help With Gameboy "Yoshi" Sprite Hack
« Reply #6 on: May 11, 2013, 10:47:27 pm »
Here's a screenshot of what Buddermilk is talking about:



This only occurs if you hatch at least 10 eggs in A-Type, then lose.