RE: [stella] Flicker-free background demo

Subject: RE: [stella] Flicker-free background demo
From: "Lee Fastenau" <stella@xxxxxxxxxxxxxxx>
Date: Mon, 3 Jan 2005 08:16:48 -0600
> Here's a demo of flicker-free background graphics.  These are 4K images
> which should be viewed on actual hardware rather than emulators.  On
> actual
> hardware this system has no flicker.  As you can see from the sample
> images,
> I'm playing with something that just looks like BoulderDash but isn't
> actually BoulderDash.  Isn't anyone going to ask how it's done :) ?!
> Cheers
> A

My 2600 isn't hooked up yet (since a major desk reconfiguration), but
judging from what I'm seeing in Z26, every third line switches between each
of the following color pairs at 60Hz (or 50Hz), allowing for a distinct
secondary color:

R <-> G (Yellow) 
G <-> B (Cyan)   
B <-> R (Magenta)

The clear, non-flickering primary and secondary colors lay the groundwork
for easily perceived additional colors, including white.

The nice thing about this method is that no colors are represented by only 1
of 3 rows, so striping isn't as bad as, say Spasticolor.

R <-> 
  <->   (Only one black line out of three)
  <-> R

And secondary colors are represented by all three lines, with one line being
the solid color generated with imperceptible flicker and the other two using
proximity to "suggest" the secondary color:

R <-> G (Yellow)
G <->   
  <-> R (Lines 2 and 3 suggest Yellow)

The only questions that remain for me are: Isn't every other frame of a 60Hz
(50Hz) display shown offset by half a scanline (interlaced)?  Isn't that how
Spasticolor operated?  Does your method actually flicker at 30Hz?

Thanks for sharing! :)


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