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1. Adrian Cochrane (alcinnz@floss.social)'s status on Wednesday, 01-Mar-2023 16:47:47 JST Adrian Cochrane

   Over the next few days I think I'll write some threads about how computer graphics works. (I've started some videos on the topic, but those are a lot of work...)

   Let's start with some of the early techniques!

   It is the 1980s, maybe 1970s. You want to play with some of these new-fangled digital "computers" as a medium for entertainment. One problem: memory is expensive!

   You need to generate a lot of data 30+ times a second in a way we're used to interpreting, & have nowhere to store it.

   1/?

   • Adrian Cochrane (alcinnz@floss.social)'s status on Wednesday, 01-Mar-2023 16:54:26 JST Adrian Cochrane

     in reply to

     Designing your own hardware specifically for the game you want to create would've provided guidance for how to address this issue. Then "videogame consoles" would take the popular techniques & move them into peoples' homes.

     Monitors of the day shot electrons towards the viewer to hit a phosphorescent coating, lighting it up. Magnets would direct these electrons to every point onscreen. Or maybe instead you hook it up to a control unit interpreting some "vector graphics" paths!

     2/?

   • Adrian Cochrane (alcinnz@floss.social)'s status on Wednesday, 01-Mar-2023 17:05:56 JST Adrian Cochrane

     in reply to

     To output a digital image to a screen you essentially need to keep an X & a Y counter. Most games added a bit of extra circuitry allowing the CPU to configure a handful of coordinates which when reached by those counters triggers a configured image to start being sent out. These are called "sprites"!

     Some early machines like the Atari 2600 were too cheap to afford a full sprite renderer, not handling the Y axis at all. Amongst other things...

     3/4!

   • Adrian Cochrane (alcinnz@floss.social)'s status on Wednesday, 01-Mar-2023 17:15:44 JST Adrian Cochrane

     in reply to

     Some sprite hardware took a sorted list of sprites to iterate over, drastically increase spritecounts.

     To render game maps, or text in certain charsets (i18n was limited), we'd have one memory segment reference indices in a 2nd memory segment. Depending on how cheap RAM is we might connect 2 memory chips together, or we might copy the tiles into place.

     Using similar smaller-scale circuitry we can compress images with limited colour palettes.

     We can combine these techniques.

     4/4 Fin for now!