[BUG][FIX] Pen trails form depth (updated version fixes World trails,
too)
Bert Freudenberg
bert at isg.cs.uni-magdeburg.de
Fri Jul 4 17:38:45 UTC 2003
"Change Set: colorSeesTrails-bf
Date: 4 July 2003
Author: Bert Freudenberg
Makes the pen trail form use the display depth instead of 8 bits. This
lets the color:sees: test work on pen trails, too (otherwise there
likely is a color mismatch). Also makes trails visible to the color
seer if they are on the World background, not just in playfields."
Am Freitag, 04.07.03 um 16:38 Uhr schrieb Bert Freudenberg:
> Am Freitag, 04.07.03 um 14:46 Uhr schrieb Jeff Longland:
>
>> I'm a new Squeak user and I'm not trying to tackle anything too
>> difficult at
>> the moment, or at least I didn't think so initially. I'm working on
>> creating an object (a snake) that will travel along the edge of a
>> rectangle
>> while leaving a trail. As the snake works around the rectangle and
>> comes
>> back to its starting point, the snake will view the existing trail as
>> the
>> new wall - making smaller and smaller rectangles, until the snake has
>> covered the surface area of the rectangle. Ideally, I'd like to be
>> able to
>> move the snake object into any shape and it will cover the surface
>> area in
>> the same manner as the above mentioned rectangle. I've been using
>> penDown
>> to create a pen trail behind the snake, but my major problem is that
>> the
>> sensor on my object is unable to view the pen trail. I've searched
>> around
>> quite a bit and I've seen mention of transparent playfields,
>> adjusting the
>> display depth, and a method that refreshes the playfield - but Squeak
>> documentation seems to be somewhat scattered. I've been playing with
>> Squeak
>> for a while now, and I'm slowly getting the hang of everything - but
>> it's
>> taken quite a while. Does anyone have any suggestions on how I can
>> make the
>> pen trails visible to my sensor? Or any other suggestions for the
>> project
>> and my journey through Squeak?
>
> I would not consider this to be a newbie question, but rather a bug
> report ;-)
>
> This indeed seems to be a problem with dithering. The pen trails use
> an 8 bit color form, while the world is displayed in 16 or 24 bits.
> This makes the color of the trails slightly different from the color
> in the color-sees tile.
>
> Try the attached changeset. It makes the trails use the same depth the
> display has. After installing, you need to clear the pen trails once.
> See the attached picture for my implementation, I'm almost sure I did
> this faster than Edgar :-)
>
> To install a changeset, open a file list, select the file, and chose
> "file in".
>
> -- Bert
This new version makes trails in the World (on the "background")
visible to the "color sees" test, too.
-- Bert
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