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Deep Winter Thoughts

Posted on

By Kodiak


As the year draws to a close and I sit here mindful of the freezing, snowy scene outside, my thoughts turn again to the tech demo videos I released back in early 2020 of Deep Winter on the Commodore 64, my planned sequel to Parallaxian.

It's true to say I rushed the coding side of it, being pressed for time (as usual), but the fundamentals are there in the form of a nice NMI (Non-Maskable Interrupt) chain that interrupts the IRSTs (Raster Interrupts).

The principle is simple: let the IRSTs do the heavy-lifting of scrolling the parallax landscape and meanwhile we interrupt the scroll code with precisely timed NMIs to nip in quickly, plex the tree sprites, and get out again quickly, without skipping a heartbeat.

Of course, the whole NMI-plexing-while-suspending-IRSTs concept has its origins in Parallaxian and has also been ported into the chase levels of my good friend John Henderson's game in development, The Wild Wood, which I have been helping out with, as per this detailed tech article.

It's a truly great way to mix sprite plexing and scrolling based on screen split effects on the venerable C64, so one day I hope to reveal it in all its gory technical detail, ideally after Parallaxian's release.

In the meantime, check out the snowstorm effect in the clip below; it's a new recording and while it suffers from some of the same video capture problems that plagued the Youtube version, the quality is better; this is an effect that needs a real C64 (or a VICE running without rival applications slowing it down) to truly execute flawlessly.

NOTE: The falling snow effect is sensitive to your stream quality + the processing capabilities of the device it's viewed on. However, you can download it from the settings dialogue on the embedded player above and play back with little or no "banding" spoiling the effect.

That effect is entirely built on the Toggleplex concept; in this example, a sprite "canvas" is projected over the landscape and then simple falling snow sprite definitions are updated as required.

The game itself is to be a survival-against-the-wild experience, where each day you must source enough food, water, heat, medical aid, clothing, shelter, etc., to survive until spring, while also avoiding dangerous interactions with wild animals and other survivalists in the mountains.

Gameplay is envisaged as a combination of problem-solving, exploration and strategy elements, so it should be quite different to almost anything ever seen on the C64 prior to it.

More information on the game concept in this article.

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PS: Don't forget to check the home page regularly for more articles like this and visit the Everything64 Forum to comment further.

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