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Author Topic: Alien 3 (SNES) Graphic Edit Help  (Read 1007 times)

Robin64

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Alien 3 (SNES) Graphic Edit Help
« on: January 05, 2018, 05:29:32 am »
So while trying to get as many games working in Canoe (the built-in SNES Mini emulator) as possible, one issue that arose is that Alien 3's password entry cursor doesn't display. So I proposed a patch that edits that cursor to use the same palette as the rest of the letters on the screen in the hope that this might fix it.

However, I cannot for the life of me find that tile in the ROM. The rest of the game seems to there in plain view, but I cannot see the cursor at all, so changing it doesn't seem to be easy.



My notion was that maybe changing it from how it looks now on the left to the one on the right would get the SNES Mini displaying it.



Anyone who could possibly help with this? :)

Squall_FF8

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Re: Alien 3 (SNES) Graphic Edit Help
« Reply #1 on: January 05, 2018, 01:28:35 pm »
Hey Robin64, from what program is the first screenshot?

Vanya

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Re: Alien 3 (SNES) Graphic Edit Help
« Reply #2 on: January 06, 2018, 03:14:24 pm »
That doesn't sound to me like it would be an issue with the palette.
Why would the emulator not be rendering all the colors?

matt!

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Re: Alien 3 (SNES) Graphic Edit Help
« Reply #3 on: February 11, 2018, 04:59:04 pm »
Looking at No$sns Vram Viewer the cursor is not a tile on the background but a sprite rendered using the OAM (Object Attribute Memory).
Maybe a clue is that the cursor doesn't align with the tile grid like the rest of the graphics on this screen?



You can see tile address is 7CC0 which is a number so high it only exists when rendering the tiles as 2bpp/4greys or 4bpp/16greys (and not 8bpp/256 colours).



So I would guess Canoe does not support those drawing modes?

If so, a patch would need to draw the cursor as a different tile that exists in the 8bpp/256colours tileset and draw it in that mode.
« Last Edit: February 11, 2018, 05:14:50 pm by emsef »

sluffy

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Re: Alien 3 (SNES) Graphic Edit Help
« Reply #4 on: February 11, 2018, 07:12:25 pm »
Hm.. ponder. All OAM sprites are 4bpp. Fixed restriction. Mortal Kombat III uses 8bpp background + 4bpp cursor and list says okay there.

Alien3 is a 16x16 cursor? That's really big. No priority bit set.. have to check this more carefully and play around with layering. But it could be a palette issue though.

Check this more later. ;)



Okay.. background stars, planets are drawn using sprites! But cursor's completely gone and not in back. Huh.

Background is drawn as grid of sprites 8x7 wide-high. Means it already uses 32 tiles per line. We get max 34 tiles and anything afterwards disappears. But cursor is sprite 1/128 so it should have top priority.

Irony is all sprites tiles use OBJ palette 0. Game's already FastROM.


================================
================================


Auto-merge bump vs edit.


Think I understand problem. It's Range-Time Over: sprite priority on same line. Please try these changes:

C865 = 8F 7C 0B 00
C86C = 8F 7E 0B 00
C873 = 8F 9E 0B 00
This will make cursor top sprite priority.



Optional:
C869 = A9 CC 31
This will make cursor go on top of password background. Go to 'C'ancel, 'L'eft, 'R'ight, 'O'K to see effect.

Unsure if bug or intended design. But partial neat change.
« Last Edit: February 12, 2018, 12:32:47 pm by sluffy »

Robin64

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Re: Alien 3 (SNES) Graphic Edit Help
« Reply #5 on: February 12, 2018, 12:37:45 pm »
Success!