OK. We got Sprites. We got Backgrounds. What else?

I hear that the third (and final) graphical layer is “Window”. So a bit of reading and that looks like it’s useful for HUD style content (to save sprites – the Game Boy can only display 12 of those in any row). Out-of-the-box it starts at the top left of the screen but while reading up I found some clever shenanigans on a forum to get it placed at the bottom instead. Useful stuff, but I didn’t fancy doing HUD stuff tonight.

I fancied playing with that “fade” effect you often see in games. It’s apparently super useful when replacing whole screens to prevent glitchy behaviour. i.e. you fade it to a single colour, replace the screen content, and fade it back in. Looks cool, and hides quirks.

Let’s do that with a background.

I need an image to play with, so I grabbed a picture of Thom Yorke from the “No Surprises” video (because who wouldn’t want a tiny Thom trying not to drown in their Game Boy?) and set about converting it to a useful format. In GIMP of all things.

So “The GIMP” has certainly moved on since I last used it (maybe 15 years ago?). At first I did so to follow a tutorial on displaying full screen images which failed when I found that there’s no way to get the pre-requisite pcx2gb.exe to run on my 64-bit Windows machine. Oh well. Still, the brief diversion into The GIMP did re-open my eyes to the concept of dithering (the colour palette trick) so I was able to process a nice image in the correct dimensions at a reduced palette.

Thanks, The GIMP! I should never have left you for Photoshop

Right, so getting it into a Game Boy format. Well pcx2gb didn’t work, but thanks to an old post and the Internet Archive (I’m sensing a theme here) I dug up a REALLY neat online tool for generating the tiles and the map! I should try and grab a copy before it goes away forever.

Paste that data into a .c file, write a super-basic loader and ta-da!

You can’t see it, but this image’s filename is thom_boy.png

(Why the border? Well, the Game Boy has limits, and enough unique tiles to fill the whole screen is just too much. Giving it a 1-tile border allowed a single tile to be repeated all the way around, vastly reducing the number of unique tiles needed.)

Let’s make him fade.

As usual, it didn’t take long to find a great example. I’d already read up on the principles of how it’s done (palette swap each colour towards the lightest/darkest one) and some kind person calling themselves “cabbage” uploaded some sample code.

It didn’t take long to pull apart, reassemble, and integrate onto my little test project.

Faaaaaddeee Ouuuuuuttt aggaaaaaaaaaaaaaaaaaaain
(Yes, I know that’s not this song)
(Yes, that’s why I thought of using Thom

Time Spent: About 1.5 hours. A lot of which was finding tools, installing GIMP and playing with Thom’s face.

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1 Comment

  1. Dude you made my day (night actually) with this post I’ve been looking for a pcx2gb alternative for AGES!

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