# [pstricks] viewpoint in pst-solide3D

Patrice MÉGRET Patrice.MEGRET at umons.ac.be
Thu Nov 12 18:20:37 CET 2015

Dear list,

I am playing with pst-solide3D by making the examples of Herbert's book.

In particular, example 23-06-14 and I wanted to see the effect of viewpoint.

If I correctly understand the spherical coordinates (r,\theta,\phi): r is the length of the vector OV, \theta is the angle between xz plane and the plane comprising vector OV and perpendicular to the xy plane and \phi is the angle between vector OV and z axis.

So viewpoint=50  45 90 rtp2xyz is viewing the cube from the z axis and 45 degree away from the x axis. But the code below does not display what I expect: it seems that \theta is set to zero instead of 45 degree
If I put viewport=50  45 89.9 rtp2xyz, I get what I expect.
Look at the code below to see my trouble.

Bets regards,
Patrice

%%

%%  A DANTE-Edition example

%%

%%  Example 23-06-14 on page 396.

%%

%%  Copyright (C) 2011 Herbert Voss

%%

%%  It may be distributed and/or modified under the conditions

%%  of the LaTeX Project Public License, either version 1.3

%%

%%  See http://www.latex-project.org/lppl.txt for details.

%%

%%

%% ====

% Show page(s) 1

%%

\documentclass[]{article}

\pagestyle{empty}

\setlength\textwidth{105.70511pt}

\setlength\parindent{0pt}

\usepackage{pst-solides3d}

\begin{document}

\psset{viewpoint=50 45 90 rtp2xyz,Decran=50}

\begin{pspicture}(-2,-2)(2,2)

\psSolid[object=cube]

\axesIIID[showOrigin=false](2,2,2)(4,4,4)

\end{pspicture}

\vspace{5cm}

\psset{viewpoint=50 45 89.9 rtp2xyz,Decran=50}

\begin{pspicture}(-2,-2)(2,2)

\psSolid[object=cube]

\axesIIID[showOrigin=false](2,2,2)(4,4,4)

\end{pspicture}

\end{document}

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