Strange dpy 3000 instruction in snowflake
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Bill E
Mar 20, 2026, 9:12:08 AMMar 20
to [PiDP-1]
I found a problem with snowflake conflicting with a lightpen feature.
Snowflake does a dpy 3000, 733007. But, the 3000 isn't documented in the handbook.
It is normally ignored, but it happens to be the lightpen aperture setting flag when the
lightpen is enabled.
It also does a completion wanted version of the same, 727007. The completion is legal, but again the 3000 bit is a mystery.
Anyone know what this was supposed to do in snowflake? Intensity setting or something?
I've put in a special check for this, but that's a total hack. If I understand the intent, I can do a clean fix.
Bill
MICHAEL GARDI
Mar 20, 2026, 9:19:04 AMMar 20
to Bill E, [PiDP-1]
This might be the code to switch the origin to the lower left corner.
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Bill E
Mar 20, 2026, 9:35:02 AMMar 20
to [PiDP-1]
Ah, of course. Thanks, forgot about that. Well, I support that also. Updated to make it mutually exclusive with the lp.
Bill
Bill E
Mar 20, 2026, 9:40:23 AMMar 20
to [PiDP-1]
That prompted me to turn on dpy origin setting in my config file and try it. It really changes the snowflake appearance, kind of cool. I think I like the center origin mode better, though.
If anyone is inspired to try the same, in the config file turn off sdb and lightpen, turn on dpyshift.
Bill
MICHAEL GARDI
Mar 20, 2026, 10:41:06 AMMar 20
to Bill E, [PiDP-1]
If you want to see what Bill is talking about and don't have his cool extensions installed you can check out the masswerk:snowflake demo. Use Options->Outside-In. And I agree Bill the center origin is more interesting.
Mike
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Norbert Landsteiner
Mar 20, 2026, 1:46:03 PMMar 20
to [PiDP-1]
See also the discussion / walk-trough of the code here:
Includes a discussion of the display routines. There's also a rather over-engineered random number generator worth mentioning.
(I once made a Christmas-special [1] with a text message spliced in and, in order to save some runtime for the soft font rendering, I replaced this with the much faster RNG used in Spacewar! [2]. Works, but still flicker-y.)
Cheers,
norbert
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