[pstricks] some questions on pst-solide3d

[Zbigniew Nitecki]

I beginning to learn (very slowly) the working of pst-solides3d, using  
an adaptation of the Moebius band example on the melusine.eu.org  
website.  Here is the part of the code I am working on (the first line  
makes sure TeXShop uses ghostscript+latex, not pdflatex;  the  
commented package calls are ones I might like to make later):
**************************************************************
%!TEX TS-program =  latex

\listfiles
\documentclass[11pt]{article}
%\usepackage{amsmath, amssymb}
\usepackage[dvipsnames, svgnames]{pstricks}
\usepackage{pst-plot, pst-math, pst-3dplot}
\usepackage{pst-grad, pst-func, pst-text}
\usepackage{pstricks-add}
\usepackage{pst-solides3d}

%\usepackage{graphicsmacros}
%\usepackage{basicmacros}
%\usepackage{calculusmacros}

\title{Brief Article}
\author{The Author}

\begin{document}
\maketitle
\begin{figure}[htbp]
\begin{center}
	\begin{pspicture}(-6,-3)(6,3)
		\psset{unit=1.5}
		\defFunction{mobius}(u,v)
			{2 u v Cos mul add 2 v mul Cos mul}
			{2 u v Cos mul add 2 v mul Sin mul}
			{u v Sin mul}
			
		\psset[pst-solides3d]{viewpoint=20 10 5,Decran=40,lightsrc=0 10 10}
		\psSolid[object=surfaceparametree,linewidth=0.75\pslinewidth,
			base=0.2 0.25 0 pi,linewidth=0.1,
			function=mobius,
			ngrid=.025]
		\psSolid[object=surfaceparametree,linewidth=0.75\pslinewidth,
			base=-0.25 -0.2 0 pi,linewidth=0.1,
			function=mobius,
			ngrid=.025]
		\psSolid[object=surfaceparametree, linewidth=0.5\pslinewidth,
			base=-0.25 0.25 0 pi, fillcolor=lightgray!50, incolor=white!50,
			function=mobius,
			ngrid=.05]

	\end{pspicture}
\caption{Moebius Band}
\label{fig:Moebius}
\end{center}
\end{figure}



\end{document}
*******************************************************************************************
This creates a reasonable facsimile of the picture on the website  
(except that I have changed th e colors, and added a lightsource---a  
primary reason to use this package).

However, several items puzzle me:

1. Where do the limits on the parameters u and v get set?  If I want  
the width of the band to
change, where do I modify the code?

2. what does the !50 after the colors do?

3. What is the role of base=...?


Zbigniew Nitecki
Department of Mathematics
Tufts University
Medford, MA 02155

telephones:
Office    (617)627-3843
Dept.    (617)627-3234
Dept. fax    (617)627-3966
http://www.tufts.edu/~znitecki/

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