<html><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; ">I am continuing with my attempt to draw a normal vector field on the Moebius band.<div>With Juergen's help, I have generated both the band and the field (there are some minor problems with the field, which are irrelevant to my present question). I would like the vector field arrows to obey hidden lines rules. If I draw the field first and then the band, any part of the field that would normally appear in front of the band is overwritten by the band. If I do it in the opposite order, then the whole field (including arrows that should be hidden by the band) shows up. setting visibility=false doesn't seem to do it. So I tried to mimic the fusion of solids as in the documentation. However, I get a strange reaction. My code is</div><div>*******************************************************************</div><div><div>\begin{figure}[htbp]</div><div>\begin{center}</div><div><span class="Apple-tab-span" style="white-space:pre"> </span>\begin{pspicture}(-6,-3)(6,3)</div><div><br></div><div><span class="Apple-tab-span" style="white-space:pre"> </span>\defFunction{mobius}(u,v)</div><div><span class="Apple-tab-span" style="white-space:pre"> </span>{2 u v Cos mul add 2 v mul Cos mul}</div><div><span class="Apple-tab-span" style="white-space:pre"> </span>{2 u v Cos mul add 2 v mul Sin mul}</div><div><span class="Apple-tab-span" style="white-space:pre"> </span>{u v Sin mul}</div><div><span class="Apple-tab-span" style="white-space:pre"> </span></div><div><span class="Apple-tab-span" style="white-space:pre"> </span>\defFunction{centercircle}(t)</div><div><span class="Apple-tab-span" style="white-space:pre"> </span>{2 t mul Cos 2 mul} </div><div><span class="Apple-tab-span" style="white-space:pre"> </span>{2 t mul Sin 2 mul} </div><div><span class="Apple-tab-span" style="white-space:pre"> </span>{0}</div><div><span class="Apple-tab-span" style="white-space:pre"> </span></div><div><span class="Apple-tab-span" style="white-space:pre"> </span>\psset[pst-solides3d]{viewpoint=20 10 15,Decran=40,lightsrc=10 20 10}</div><div><span class="Apple-tab-span" style="white-space:pre"> </span></div><div><span class="Apple-tab-span" style="white-space:pre"> </span>\psSolid[object=courbe,</div><div><span class="Apple-tab-span" style="white-space:pre"> </span>range= 0 pi,</div><div><span class="Apple-tab-span" style="white-space:pre"> </span>linewidth=1.5\pslinewidth,</div><div><span class="Apple-tab-span" style="white-space:pre"> </span>linecolor=blue,</div><div><span class="Apple-tab-span" style="white-space:pre"> </span>function=centercircle,</div><div><span class="Apple-tab-span" style="white-space:pre"> </span>ngrid=1,r=0]</div><div><br></div><div><br></div><div>\codejps{</div><div><span class="Apple-tab-span" style="white-space:pre"> </span>/Band{</div><div><span class="Apple-tab-span" style="white-space:pre"> </span>\psSolid[object=surfaceparametree, linewidth=0.5\pslinewidth,</div><div><span class="Apple-tab-span" style="white-space:pre"> </span>base=-0.4 0.4 0 pi, fillcolor=lightgray!30, incolor=white,</div><div><span class="Apple-tab-span" style="white-space:pre"> </span>function=mobius,</div><div><span class="Apple-tab-span" style="white-space:pre"> </span>ngrid=.05]</div><div><span class="Apple-tab-span" style="white-space:pre"> </span>} def</div><div><span class="Apple-tab-span" style="white-space:pre"> </span></div><div><span class="Apple-tab-span" style="white-space:pre"> </span>/Field{</div><div><span class="Apple-tab-span" style="white-space:pre"> </span>\multido{\rv=-0.35+0.35}{10}{%</div><div><span class="Apple-tab-span" style="white-space:pre"> </span>\psSolid[object=vecteur,</div><div><span class="Apple-tab-span" style="white-space:pre"> </span>linecolor=lightgray,</div><div><span class="Apple-tab-span" style="white-space:pre"> </span>args= \rv\space Sin \rv\space 2 mul Cos neg</div><div><span class="Apple-tab-span" style="white-space:pre"> </span>\rv\space Sin \rv\space 2 mul Sin neg</div><div><span class="Apple-tab-span" style="white-space:pre"> </span>\rv\space Cos </div><div><span class="Apple-tab-span" style="white-space:pre"> </span>](\rv\space 2 mul Cos 2 mul, \rv\space 2 mul Sin 2 mul, 0)</div><div><span class="Apple-tab-span" style="white-space:pre"> </span>}</div><div><span class="Apple-tab-span" style="white-space:pre"> </span>} def</div><div><span class="Apple-tab-span" style="white-space:pre"> </span>Band Field solidfuz</div><div><span class="Apple-tab-span" style="white-space:pre"> </span>drawsolid**}</div><div><span class="Apple-tab-span" style="white-space:pre"> </span>\end{pspicture}</div><div>\caption{Moebius Band}</div><div>\label{fig:Moebius}</div><div>\end{center}</div><div>\end{figure}</div><div><br></div><div>***************************************************************************</div><div>and the console gives the error message</div><div>***********************************************************</div><div><div>`PSTSOLIDESIIID' v4.10, 2008/07/24)) (./pst-solides3dTest.aux)</div><div>Runaway argument?</div><div>{ /Band{ \psSolid [object=surfaceparametree, linewidth=0.5\pslinewidth \ETC.</div><div>! Paragraph ended before \codejps was complete.</div><div><to be read again> </div><div> \par </div><div>l.52 </div><div> </div><div>******************************************************</div><div>and the field and centercircle get drawn, but the band is not.</div><div><br></div><div>What is a correct procedure?</div></div><div> <span class="Apple-style-span" style="border-collapse: separate; color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-align: auto; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0; "><p style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><font face="Helvetica" size="3" style="font: normal normal normal 12px/normal Helvetica; "><br class="Apple-interchange-newline">Zbigniew Nitecki</font></p><p style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><font face="Helvetica" size="3" style="font: normal normal normal 12px/normal Helvetica; ">Department of Mathematics</font></p><p style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><font face="Helvetica" size="3" style="font: normal normal normal 12px/normal Helvetica; ">Tufts University</font></p><p style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><font face="Helvetica" size="3" style="font: normal normal normal 12px/normal Helvetica; ">Medford, MA 02155</font></p><p style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; font: normal normal normal 12px/normal Helvetica; min-height: 14px; "><br></p><p style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><font face="Helvetica" size="3" style="font: normal normal normal 12px/normal Helvetica; ">telephones:</font></p><p style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><font face="Helvetica" size="3" style="font: normal normal normal 12px/normal Helvetica; ">Office<span class="Apple-converted-space"><span class="Apple-converted-tab"> <span class="Apple-converted-space"> </span></span></span>(617)627-3843</font></p><p style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><font face="Helvetica" size="3" style="font: normal normal normal 12px/normal Helvetica; ">Dept.<span class="Apple-converted-space"><span class="Apple-converted-tab"> <span class="Apple-converted-space"> </span></span></span>(617)627-3234</font></p><p style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><font face="Helvetica" size="3" style="font: normal normal normal 12px/normal Helvetica; ">Dept. fax<span class="Apple-converted-space"><span class="Apple-converted-tab"> <span class="Apple-converted-space"> </span></span></span>(617)627-3966</font></p><a href="http://www.tufts.edu/~znitecki/">http://www.tufts.edu/~znitecki/</a></span> </div><br></div></body></html>