[GRASS5] Re: NVIZ cleanup (update)

Helena Mitasova hmitaso at unity.ncsu.edu
Tue Jun 10 15:36:38 EDT 2003

Can somebody confirm/test that there is still a problem with nviz top2
in RH9 under KDE (it does not open properly, see 
It works OK under gnome (that I use). I thought it was RH8 problem but
it still does it in KDE in RH9.

Bob, I will test the changes as soon as I come home on my home machine.
The nearclip/farclip
really make a lot of difference (e.g. with the current CVS version of
a small raster 200x300 had lot of holes while the larger DEM with around
1000rc was perfect).
I will test the new constants with different sizes (should that optimum
be dependent on the size of the raster?)

> Paul
> On Mon, 9 Jun 2003, Bob Covill wrote:
> > Markus, Paul;
> >
> > I figured I would send you an update of the NVIZ stuff for more testing.
> >
> > I have cleaned up the off screen stuff. The compile flags are now
> > GLX_PBUFFER_BIT and GLX_PIXMAP_BIT instead of the previous VERSION
> > options. I have finally got the GLX Pixmap routines working (better). I
> > realized that the image was blank due to the fact that the lights were
> > not initialized in the new context. I have added an off-screen compenent
> > to the "max. size" image output. When the user selects this, an
> > off-screen context is open (if available) at the screen size and the
> > tiles are drawn to make up the max. viewport size. If off-screen
> > rendering is unavailable, the tiles are drawn in the users current window.
> >
> > I have reset the nearclip / farclip defaults to 10 and 10000
> > respectively. This was at the heart of the error reported by Helena with
> > mismatched surfaces at different views. These values are used in
> > gluPerspective. The greater the difference between these values the
> > lower the accuracy of the Z buffer. An optimum ratio for the values is
> > approx., 1000. It would be nice to make these values auto-respond to the
> > users current view to avoid scene clipping when outside the range.
> >
> > I have cleaned up a couple of other bugs reported by Helena. The first
> > was NVIZ crashing when a vector was loaded outside the current region.
> > The exit from this is much more graceful and the vector is not loaded at
> > all. The second error was crashes related to cutting planes drawn
> > between surfaces with diffeent resolutions (nviz). An error is now
> > reported to standard output and the cutting plane is not drawn.
> >
> > Again, let me know if you have any questions or problems. Should we
> > apply to CVS soon so others can test?
> >
> > --
> > Bob Covill
> >
> > Tekmap Consulting
> > P.O. Box 2016
> > Fall River, N.S.
> > B2T 1K6
> > Canada
> >
> > E-Mail: bcovill at tekmap.ns.ca
> > Phone: 902-860-1496
> > Fax: 902-860-1498
> >
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