[GEM-dev] [ pd-gem-Bugs-3281206 ] thin white primitive borders are shown despite texture

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Bugs item #3281206, was opened at 2011-04-08 23:07
Message generated for change (Comment added) made by zmoelnig
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Category: rendering (e.g. display)
Group: any operating system
Status: Pending
Resolution: None
Priority: 7
Private: No
Submitted By: Matteo Sisti Sette (sistisette)
Assigned to: Nobody/Anonymous (nobody)
Summary: thin white primitive borders are shown despite texture

Initial Comment:
Sometimes, depending on their size and/or position, rectangles (and I guess other polygons too but I mainly work with rectangles) are shown with a thin white border even if they are textured with a pix that has no white pixel in the proximity of the border, e.g. a completely black image or an image whose pixels close to the border are all black or transparent.

This has been there for years, I've always seen this happen since I use gem, across many versions. This happens both with Linux and Windows, i don't know on Mac OS.

If a rectangle is moving or changing size, the borders appear and disappear. Most of the time they are absent, I mean the values of position and size that cause the borders to appear are just a small fraction of the total. 

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>Comment By: IOhannes m zmölnig (zmoelnig)
Date: 2011-08-16 18:33

Message:
it's hardware/driver specific as the openGL standard doesn't specify
exactly how it ought to be done (afair); i mainly follow cyrille's arguing
here.

the workaround is to e.g. set "repeat" mode and/or the "quality" mode of
texture.

you can apply a global defaul by adding lines for "texture.quality" and
"texture.repeat" to your gem.conf;
something like:
<gem.conf>
texture.quality 0
</gem.conf>

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Comment By: Matteo Sisti Sette (sistisette)
Date: 2011-08-16 18:27

Message:
Sorry it was me asking the last question (damn the fake  "remember me"
checkbox, I reported that but the admins like the way it is)

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Comment By: Nobody/Anonymous (nobody)
Date: 2011-08-16 18:24

Message:
What hardware/driver is this specific to? What's the workaround in
gem.conf?

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Comment By: IOhannes m zmölnig (zmoelnig)
Date: 2011-08-16 18:01

Message:
given that the problem is hardware/driver specific, there is a workaround
_and_ the workaround can be done globally using gem.conf (in >=0.93), i
think this can be closed.

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Comment By: Matteo Sisti Sette (sistisette)
Date: 2011-04-23 17:39

Message:
Does the hardware really interpolate textures the wrong way? Are we sure
Gem is asking the hardware the right thing? If "repeat" is the fix, i
suspect it may mask the issue (i.e. make it less evident in some but not
all situations) rather than fix it, but I haven't tried it actually.

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Comment By: Cyrille Henry (nusmuk)
Date: 2011-04-09 00:35

Message:
This is not a gem problem. it's the way the hardware interpolate a texture.
i don't remember the exact configuration, but changing the default value
of "quality" and/or "repeat" of pix_texture change can fix this problem.
since it's not gem fault, and gem offer a solution, i think this can be
closed.


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Comment By: Matteo Sisti Sette (sistisette)
Date: 2011-04-08 23:10

Message:
I hope it is ok to rise the priority. Though this is an old bug, it is a
real showstopper in a range of situations.

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https://sourceforge.net/tracker/?func=detail&atid=507079&aid=3281206&group_id=64325