Re: [Dri-devel] mga and very slow line rendering.

[Thomas H. <th...@br...>]

Keith Whitwell wrote:

> > > > Same display list as case 1. This is where the problems occur. It's very slow and
> > > > even particularly more so when "somon" is used.  Most of the time (almost all) is
> > > > spent in ioctl() which, from strace is fd 4 which, again from strace, _seems_ to
> > > > be /dev/dri/card0. There is also some rendering errors here if GL_QUADS are used
> > > > and a quad intersects the window border. Then it seems to be split up in multiple
> > > > polygons and sometimes a line is drawn around each of them, instead of around all
> > > > of them as a group, introducing extra lines in the model.
> > > > (I can send an image on request).
> > >
> > > I was pretty sure we'd nailed these problems.  Can you try to make a small
> > > demo that demonstrates the problem.  This is the most helpful way to report a
> > > bug.
> > >
> >
> > Hmm. I'll try to make a short glut application that renders a single triangle / quad
> > and reproduces the problem.  If I'm successful  I'll submit it to the bug tracking
> > system.
>
> OK,
>
> Here's a replacement for extras/Mesa/src/clip_funcs.h which solves the
> clipping problem on my machine.  Let me know how you go.  (The changes are
> small but have a lot of spurious whitespace stuff that confuses diff, so I'm
> attaching a replacement file.)
>
> Keith

Yes.  This patch fixes the most annoying lines, However there is still a line present
exactly at the window border on _some_ of the clipped polygons in my application.  This
type of line can be seen also if you run the example program (the thin red line on top of
the screen)

http://www.geocrawler.com/lists/3/SourceForge/680/25/3901584/

But many OpenGL implementations seem to do the same.
(Nvidia's drivers, Xig's new MGA G400 drivers and hp's OpenGL for hp-ux.)

I'm not totally sure the line shouldn't be there, but in case it really should be present
there should be a similar line on _all_ clipped polygons, not just some.


Anyway, a big improvement!!!

Best regards!
Thomas




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       Thomas Hellström, Fyrmästaregången 8, S-413 18 Göteborg, Sweden
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