bionic (3) PDL::Graphics::TriD::Rout.3pm.gz

NAME

       PDL::Graphics::TriD::Rout - Helper routines for Three-dimensional graphics

DESCRIPTION

       This module is for miscellaneous PP-defined utility routines for the PDL::Graphics::TriD module.
       Currently, there are

FUNCTIONS

   combcoords
         Signature: (x(); y(); z();
                       float [o]coords(tri=3);)

       Combine three coordinates into a single piddle.

       Combine x, y and z to a single piddle the first dimension of which is 3. This routine does dataflow
       automatically.

       combcoords does not process bad values.  It will set the bad-value flag of all output piddles if the flag
       is set for any of the input piddles.

   repulse
         Signature: (coords(nc,np);
                        [o]vecs(nc,np);
                        int [t]links(np);;
                       double boxsize;
                       int dmult;
                       double a;
                       double b;
                       double c;
                       double d;
               )

       Repulsive potential for molecule-like constructs.

       "repulse" uses a hash table of cubes to quickly calculate a repulsive force that vanishes at infinity for
       many objects. For use by the module PDL::Graphics::TriD::MathGraph.  For definition of the potential, see
       the actual function.

       repulse does not process bad values.  It will set the bad-value flag of all output piddles if the flag is
       set for any of the input piddles.

   attract
         Signature: (coords(nc,np);
                       int from(nl);
                       int to(nl);
                       strength(nl);
                       [o]vecs(nc,np);;
                       double m;
                       double ms;
               )

       Attractive potential for molecule-like constructs.

       "attract" is used to calculate an attractive force for many objects, of which some attract each other (in
       a way like molecular bonds).  For use by the module PDL::Graphics::TriD::MathGraph.  For definition of
       the potential, see the actual function.

       attract does not process bad values.  It will set the bad-value flag of all output piddles if the flag is
       set for any of the input piddles.

   vrmlcoordsvert
         Signature: (vertices(n=3); char* space; char* fd)

       info not available

       vrmlcoordsvert does not process bad values.  It will set the bad-value flag of all output piddles if the
       flag is set for any of the input piddles.

   contour_segments
       This is the interface for the pp routine contour_segments_internal - it takes 3 piddles as input

       $c is a contour value (or a list of contour values)

       $data is an [m,n] array of values at each point

       $points is a list of [3,m,n] points, it should be a grid monotonically increasing with m and n.

       contour_segments returns a reference to a Perl array of line segments associated with each value of $c.
       It does not (yet) handle missing data values.

       Algorthym
           The data array represents samples of some field observed on the surface described by points.  For
           each contour value we look for intersections on the line segments joining points of the data.  When
           an intersection is found we look to the adjoining line segments for the other end(s) of the line
           segment(s).  So suppose we find an intersection on an x-segment.  We first look down to the left
           y-segment, then to the right y-segment and finally across to the next x-segment.  Once we find one in
           a box (two on a point) we can quit because there can only be one.  After we are done with a given
           x-segment, we look to the leftover possibilities for the adjoining y-segment.  Thus the contours are
           built as a collection of line segments rather than a set of closed polygons.

AUTHOR

       Copyright (C) 2000 James P. Edwards Copyright (C) 1997 Tuomas J. Lukka.  All rights reserved. There is no
       warranty. You are allowed to redistribute this software / documentation under certain conditions. For
       details, see the file COPYING in the PDL distribution. If this file is separated from the PDL
       distribution, the copyright notice should be included in the file.