Re: [Plplot-general] real-time plplot too slow

[Alan W. I. <ir...@be...>]

On 2014-04-15 12:10-0600 Derek Lamb wrote:

> plshades is too slow for just about every imaginable real-world application, as far as I've been able to tell.  If memory serves correctly, even if you output to a PDF and open in your favorite reader, it will render incredibly slowly.  Inefficiencies in the way the color tables are calculated, I think.
>
> So, this isn't really helpful, but I thought I'd let you know it's not just you.
>
> http://sourceforge.net/p/plplot/bugs/105/

The current implementation of plshades is grossly inefficient since it
calls a plshade variant (which processes the entire x, y plane to find
regions having the appropriate shade range and then fills those
regions with a single colour) for each member of a set of contiguous
shade ranges.  So the timing scales as nX*nY*nS, where nX is the
number of X points, nY is the number of Y points, and nS is the number
of (contiguous) shade ranges = number of times plshade is called. We
would welcome a patch that reimplemented plshades in a much more
efficient manner (say with timing that scaled as nX*nY).

@Tom: until someone does that, I suggest you survey the other PLplot
methods of displaying 3D functions, i.e., plmesh*, pl[f]surf*,
plot3d*, or plcont for speed. If some/all of those have the necessary
speed for real-time plotting, then that speed is something that should
be aimed for if/when there is a new plshades implementation.

Alan
__________________________
Alan W. Irwin

Astronomical research affiliation with Department of Physics and Astronomy,
University of Victoria (astrowww.phys.uvic.ca).

Programming affiliations with the FreeEOS equation-of-state
implementation for stellar interiors (freeeos.sf.net); the Time
Ephemerides project (timeephem.sf.net); PLplot scientific plotting
software package (plplot.sf.net); the libLASi project
(unifont.org/lasi); the Loads of Linux Links project (loll.sf.net);
and the Linux Brochure Project (lbproject.sf.net).
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