<html><head><meta http-equiv="Content-Type" content="text/html; charset=utf-8"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;" class=""><div class=""><br class=""></div>Hi Martin,<div class=""><br class=""></div><div class="">"Surface" with OpenCASCADE is a bit tricky - and we are not quite yet happy yet about the implementation. It uses the OpenCASCADE "N-side filling" algorithm to create a BSpline surface using curve and/or point constraints. We could not manage to make this work without applying some fixes (see the addSurfaceFilling function in Geo/GModelIO_OCC.cpp), which (sometimes?) duplicates internal wires.</div><div class=""><br class=""></div><div class="">Any help from OpenCASCADE folks with this would be welcome...</div><div class=""><br class=""></div><div class="">To work around the numbering issues, I would recommend not numbering entities explicitly: in .geo files you can use "newp", "newl", etc.; with the API you would just let the API return a tag for you.</div><div class=""><br class=""></div><div class="">As a side note, you should avoid mixing CAD kernel commands (Line, Surface, ...), model commands (Physical Surface, ...) and mesh constraints (Transfinite Surface, ...) : the last two trigger a synchronization between the CAD kernel and the internal Gmsh model. Doing this repeatedly will degrade performance. It's better to create all CAD entities, then apply model and mesh commands.</div><div class=""><br class=""></div><div class="">Christophe</div><div class=""><br class=""><div><br class=""><blockquote type="cite" class=""><div class="">On 8 Jul 2018, at 21:18, <a href="mailto:Martin.Raedel@dlr.de" class="">Martin.Raedel@dlr.de</a> wrote:</div><br class="Apple-interchange-newline"><div class=""><div class="WordSection1" style="page: WordSection1; caret-color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none;"><div style="margin: 0cm 0cm 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><span style="color: rgb(31, 73, 125);" class="">Hello,<o:p class=""></o:p></span></div><div style="margin: 0cm 0cm 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><span style="color: rgb(31, 73, 125);" class=""><o:p class=""> </o:p></span></div><div style="margin: 0cm 0cm 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><span lang="EN-US" style="color: rgb(31, 73, 125);" class="">I want to add some information.<o:p class=""></o:p></span></div><div style="margin: 0cm 0cm 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><span lang="EN-US" style="color: rgb(31, 73, 125);" class=""><o:p class=""> </o:p></span></div><div style="margin: 0cm 0cm 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><span lang="EN-US" style="color: rgb(31, 73, 125);" class="">Yes, for the test case I could simply switch to “Plane Surface” and everything is working. But in reality, my models also consist on non-planar surfaces. I added another test as an attachment to this mail.<o:p class=""></o:p></span></div><div style="margin: 0cm 0cm 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><span lang="EN-US" style="color: rgb(31, 73, 125);" class=""><o:p class=""> </o:p></span></div><div style="margin: 0cm 0cm 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><span lang="EN-US" style="color: rgb(31, 73, 125);" class="">I found that if I increment the Line Loop and Surface numbers by 2 instead of 1, e.g. from the attached example:<o:p class=""></o:p></span></div><div style="margin: 0cm 0cm 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><span lang="EN-US" style="color: rgb(31, 73, 125);" class=""><o:p class=""> </o:p></span></div><div style="margin: 0cm 0cm 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><span lang="EN-US" style="color: rgb(31, 73, 125);" class="">Line Loop(1) = {10,2,11,3};<o:p class=""></o:p></span></div><div style="margin: 0cm 0cm 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><span lang="EN-US" style="color: rgb(31, 73, 125);" class="">Surface(1) = {1};<o:p class=""></o:p></span></div><div style="margin: 0cm 0cm 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><span lang="EN-US" style="color: rgb(31, 73, 125);" class="">Transfinite Surface(1) = {};<o:p class=""></o:p></span></div><div style="margin: 0cm 0cm 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><span lang="EN-US" style="color: rgb(31, 73, 125);" class="">Recombine Surface(1) = 60.0;<o:p class=""></o:p></span></div><div style="margin: 0cm 0cm 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><span lang="EN-US" style="color: rgb(31, 73, 125);" class="">Physical Surface(1) = {1};<o:p class=""></o:p></span></div><div style="margin: 0cm 0cm 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><span lang="EN-US" style="color: rgb(31, 73, 125);" class=""><o:p class=""> </o:p></span></div><div style="margin: 0cm 0cm 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><span lang="EN-US" style="color: rgb(31, 73, 125);" class="">Line Loop(3) = {12,4,13,5};<o:p class=""></o:p></span></div><div style="margin: 0cm 0cm 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><span lang="EN-US" style="color: rgb(31, 73, 125);" class="">Surface(3) = {3};<o:p class=""></o:p></span></div><div style="margin: 0cm 0cm 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><span lang="EN-US" style="color: rgb(31, 73, 125);" class="">Transfinite Surface(3) = {};<o:p class=""></o:p></span></div><div style="margin: 0cm 0cm 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><span lang="EN-US" style="color: rgb(31, 73, 125);" class="">Recombine Surface(3) = 60.0;<o:p class=""></o:p></span></div><div style="margin: 0cm 0cm 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><span lang="EN-US" style="color: rgb(31, 73, 125);" class="">Physical Surface(3) = {3};<o:p class=""></o:p></span></div><div style="margin: 0cm 0cm 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><span lang="EN-US" style="color: rgb(31, 73, 125);" class=""><o:p class=""> </o:p></span></div><div style="margin: 0cm 0cm 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><span lang="EN-US" style="color: rgb(31, 73, 125);" class="">no errors occur as well. This matches the error message. It seems that with the OpenCASCADE Factory, additional line loops are created internally. Changing this in my code would be possible but work I would rather avoid.<o:p class=""></o:p></span></div><div style="margin: 0cm 0cm 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><span lang="EN-US" style="color: rgb(31, 73, 125);" class=""><o:p class=""> </o:p></span></div><div style="margin: 0cm 0cm 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><span lang="EN-US" style="color: rgb(31, 73, 125);" class="">Can someone explain to me what where the different treatment of “Plane Surface” and “Surface” with respect to the line loops comes from? The<span class="Apple-converted-space"> </span><a href="http://gmsh.info/doc/texinfo/gmsh.html#Surfaces" style="color: purple; text-decoration: underline;" class="">documentation</a><span class="Apple-converted-space"> </span>says “Surface” is a “surface filling”. What does that mean exactly?<o:p class=""></o:p></span></div><div style="margin: 0cm 0cm 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><span lang="EN-US" style="color: rgb(31, 73, 125);" class=""><o:p class=""> </o:p></span></div><div style="margin: 0cm 0cm 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><span lang="EN-US" style="color: rgb(31, 73, 125);" class="">Best regards<o:p class=""></o:p></span></div><div style="margin: 0cm 0cm 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><span lang="EN-US" style="color: rgb(31, 73, 125);" class="">Martin</span><span lang="EN-US" class=""><o:p class=""></o:p></span></div><div style="margin: 0cm 0cm 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><span lang="EN-US" class=""><o:p class=""> </o:p></span></div><div class=""><div style="border-style: solid none none; border-top-width: 1pt; border-top-color: rgb(181, 196, 223); padding: 3pt 0cm 0cm;" class=""><div style="margin: 0cm 0cm 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><b class=""><span style="font-size: 10pt; font-family: Tahoma, sans-serif;" class="">Von:</span></b><span style="font-size: 10pt; font-family: Tahoma, sans-serif;" class=""><span class="Apple-converted-space"> </span>gmsh [<a href="mailto:gmsh-bounces@ace20.montefiore.ulg.ac.be" style="color: purple; text-decoration: underline;" class="">mailto:gmsh-bounces@ace20.montefiore.ulg.ac.be</a>]<span class="Apple-converted-space"> </span><b class="">Im Auftrag von<span class="Apple-converted-space"> </span></b><a href="mailto:Martin.Raedel@dlr.de" style="color: purple; text-decoration: underline;" class="">Martin.Raedel@dlr.de</a><br class=""><b class="">Gesendet:</b><span class="Apple-converted-space"> </span>Sonntag, 8. Juli 2018 17:01<br class=""><b class="">An:</b><span class="Apple-converted-space"> </span><a href="mailto:gmsh@onelab.info" style="color: purple; text-decoration: underline;" class="">gmsh@onelab.info</a><br class=""><b class="">Betreff:</b><span class="Apple-converted-space"> </span>[Gmsh] Error when switching from Built-In to OpenCascade Factory<o:p class=""></o:p></span></div></div></div><div style="margin: 0cm 0cm 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><o:p class=""> </o:p></div><div style="margin: 0cm 0cm 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class="">Hello,<o:p class=""></o:p></div><div style="margin: 0cm 0cm 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><o:p class=""> </o:p></div><div style="margin: 0cm 0cm 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><span lang="EN-US" class="">I just recently tried to switch from the built-in Factory to OpenCascade to use Boolean operations.<o:p class=""></o:p></span></div><div style="margin: 0cm 0cm 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><span lang="EN-US" class=""><o:p class=""> </o:p></span></div><div style="margin: 0cm 0cm 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><span lang="EN-US" class="">However, all of my tests involving more than one surface crash after the switch with the same error:<o:p class=""></o:p></span></div><div style="margin: 0cm 0cm 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><span lang="EN-US" class=""><o:p class=""> </o:p></span></div><div style="margin: 0cm 0cm 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><span lang="EN-US" class="">OpenCascade wire or line loop with tag 2 already exists<o:p class=""></o:p></span></div><div style="margin: 0cm 0cm 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><span lang="EN-US" class=""><o:p class=""> </o:p></span></div><div style="margin: 0cm 0cm 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><span lang="EN-US" class="">The same error occurs for all other surfaces except the first.<o:p class=""></o:p></span></div><div style="margin: 0cm 0cm 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><span lang="EN-US" class=""><o:p class=""> </o:p></span></div><div style="margin: 0cm 0cm 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><span lang="EN-US" class="">I added a simple brick geometry example. In case I comment out “SetFactory("OpenCASCADE"); “ everything works fine. If I use the line, the errors occur.<o:p class=""></o:p></span></div><div style="margin: 0cm 0cm 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><span lang="EN-US" class=""><o:p class=""> </o:p></span></div><div style="margin: 0cm 0cm 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><span lang="EN-US" class="">Can someone please point out what causes these errors and how I can fix them?<o:p class=""></o:p></span></div><div style="margin: 0cm 0cm 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><span lang="EN-US" class=""><o:p class=""> </o:p></span></div><div style="margin: 0cm 0cm 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><span class="">Best regards<o:p class=""></o:p></span></div><div style="margin: 0cm 0cm 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><span class="">Martin Rädel<o:p class=""></o:p></span></div><div style="margin: 0cm 0cm 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><span style="color: dimgray;" class=""><o:p class=""> </o:p></span></div><div style="margin: 0cm 0cm 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><span style="color: dimgray;" class="">————————————————————————</span><span class=""><o:p class=""></o:p></span></div><div style="margin: 0cm 0cm 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><b class=""><span style="font-family: Arial, sans-serif; color: dimgray;" class="">Deutsches Zentrum für Luft- und Raumfahrt</span></b><span style="font-size: 10pt; font-family: Arial, sans-serif; color: dimgray;" class=""> e.V. 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