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Last updated on Oct-18-2019 Download

Crystalis - text boxes - How?

Crystalis - text boxes - How?
by on (#51114)
I had wondered about this, as Crystalis uses both upper and lower case, and so I loaded it up in FCE Ultra and looked in the PPU viewer. To my surprise, there are NO tiles for the actual alphabet at all. They are present in the menus and whatnot.

The game uses MMC3, so is there some special trick that can be employed here?

by on (#51115)
Crystalis probably bankswitches the CHR to display text boxes. The CHR viewers in a lot of emulators just sample the bank numbers at one point on the screen, so they'll only see the tiles that were switched in at that point.

by on (#51116)
I haven't checked, but it probably uses IRQs to switch patterns, alternating between game graphics and text box characters.

You may not have been able to see the alphabet in the tile viewer, but if you notice, there is a field where you can input a scanline number (at least in FCEUXD). The default value is 0, but if you put a number that falls in the area of the text box you'll surely see the patterns used for it.

EDIT: I know that Crystalis uses at least one complex IRQ trick, in order to have multi-directional scrolling and a status bar: it uses an IRQ to skip over the status bar, which would be displayed in the middle of the screen if rendering kept going normally. Few games used this trick, but switching patterns for text boxes was very common.

by on (#51117)
tokumaru wrote:
I haven't checked, but it probably uses IRQs to switch patterns, alternating between game graphics and text box characters.


If my memory serves me correct -- you're correct. :-)