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Mr SQL

Enhanced CoCo artifacting on Atari (experimental)

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I've been experimenting with a new type of artifacting using some of the same techniques we leveraged in the 80's to render  4 and 7 color displays with the CoCo's 256x192 monochrome graphics mode.

 

In conjunction with 30 FPS full screen animation I'm getting plasma effects like these:

 

[attachment=436087:Ship releasing drone torpedo through ion field.JPG][attachment=436091:Meteor.JPG][attachment=436088:StarBlitz Plasma artifacting at 30 FPS.JPG]

 

As well as the familiar CoCo artifacting we are used to:

[attachment=436089:vertical multicolor sprite.JPG]

 

And no artifacting as expected dependant on wavelength:

[attachment=436090:meteor standard.JPG]

 

The plasma effect is materializing at 30 FPS from a pure 30 hz signal without the alternating field; the Atari has a unique signal that can paint the entire screen at 30 hz instead of half of it which is also part of it.

 

The effects vanish rendering 30 hz over 60 hz objects and are maximized at 30 FPS of animation; the extra phosphor and increased contrast (30 hz objects over nothing, not even a subcarrier) seems to potentiate the plasma effects. 

 

The video of the game shows these effects also merging with the traditional CoCo effects and some others that didn't show up as well -  gives a good idea but you really have to see it on a tube television.  

 

What do programmers who have worked with artifacting think?

 

If anyone wants to check out the source or try rendering other artifacting tricks with the code, it's Tiny BASIC, similar to the original TRS-80. The compiler is included in the download  site

 

As a related subtopic, composite mod's break the artifacting on Atari just like they did initially to the CoCo; I wonder if CoCo specialists like Boisey could create a composite mod for the Atari that would bring back the artifacting and really turn it up, like John did for Tandy when he had to revise his composite mod. Not all Atari's are equal here - the Vader has fantastic artifacting capabilities but the Jr is barely able to do CoCo artifacting and cannot do the plasma effects.

 

 

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