Re: [OctDev] convhulln options: qhull options

[Pedro T. <pt...@te...>]

QHull provides a very complete set of options. This options come in different 
families:
	- Format options 
	- Print options
	- Geomview options
	- Trace options
	- precision options
	- Q control options.

I think the most important issue to decide is what output will be handled back 
to octave and what won't. For example we've been running qhull with the s 
option (for a summary on stderr) and we didn't make use of it. 

As it was said in another post I think the struct array proposed by Paul is 
correct. (We'll need to see the format of the ridges element, probably a 
matrix containing the vertices of each ridge, always with the same dimension 
and varying length depending on the facet been simplicial or not).

        x(id).normal = <normal>
        x(id).offset = <offset>
        x(id).area = <area>
        x(id).vertices = [v1,...,vn]
        x(id).neighbors = [id1,...,idn]
        x(id).ridges = <?>

Some other kind of output like OFF file for Geomview or summary can be sent to 
a file. For this second purpose it is important to get the "TO file" option 
working. Right know it does nothing. 

I gues the most used options for qhull could be the subset presented by qhull 
on the command line:
	d : 'delaunay', Delaunay triangulation lifting the points to a paraboloid
	d Qu : 'furthest delaunay'. Furthest site Delaunay triangulation.
	v : 'voronoi'. Voronoi diagram
	v Qu: 'furthest voronoi'. Furthest site Voronoi diagram
	H1,1: 'halfspace intersection' about [1,1,0,0...]
	Qt: 'triangulated output'
	QJ: 'joggled input'
	Tv: 'verify results'
	s: 'output summary'
	i: 'vertices in facets' (This is what we actually get returned to octave)
	n:'normals'. Normals with offset for each facet (This is what I also want to 
have ;).)
	p: 'vertex coordinates'. We already have that since we parse a matrix with 
this to the function.
	Fp: 'halfspace intersections'
	Fx: 'extreme points'
	FA: 'total area and volume'
	o: 'OFF format'
	G: 'Geomview output'
	m: 'Mathematica output'
	QVn: 'print facets that include point n'
	TO file: 'output file'

As you see QVn is an "option with options" so I would eliminate it from the 
list and pass it as a string like it is done now.  The same for Hn,n and all 
the other options not listed here.

Regards,
Pedro