[Gmsh] Using gmsh as library by C++, received warning message "Staring subloop x in Line Loop 1 (are you sure about this?)

Guowei He rteycisy at gmail.com
Thu May 10 16:09:34 CEST 2012


=.=

Never mind, I've found the GEdge.h

On Thu, May 10, 2012 at 3:58 PM, Guowei He <rteycisy at gmail.com> wrote:

> Dear gmsh users and ,
>
> When the following C++ code is executed to generate a simple rectangle
> with a circular hole in it, based on the sample given by
>
> Takuya OSHIMA, Ph.D. in http://www.geuz.org/pipermail/gmsh/2011/006803.html
>
> , warning message "Staring subloop x in Line Loop 1 (are you sure about
> this?) is prompted during the command "gmsh test.geo", though the geo graph
> looks fine, the test.geo generated contains some thing like Line Loop(1) =
> {1, 2, 3, 4, -6, -5}; where 1 2 3 4 are external boundaries and 5 6 are
> edges of the circle. However a nicer approach in gmsh scripting is do
> something like
>
> // exterior boundary
> ll1 = newll; Line Loop(ll1) = { l01, l02, l03, l04 };
>
> // interstitial domain
> s1 = news;   Plane Surface(s1) = { ll1, beadSurfLoops[] };
>
> Is there some corresponding "Loops" object in gmsh library or we only use
> something like "typedef   std::vector<GEdge *> Lineloop;
> typedef std::vector<Lineloop> Loops;"?
>
> Many thanks!
>
> ///////////////////////////////////////////////////////////////////
> test.geo
> ////////////////////////////////////////////////////////////////////////////////
> cl1 = 0.08;
> Point(1) = {9.9, 8, 0, cl1};
> Point(2) = {-9.9, 8, 0, cl1};
> Point(3) = {-9.9, -8, 0, cl1};
> Point(4) = {9.9, -8, 0, cl1};
> Point(5) = {5, 5, 0, cl1};
> Point(6) = {5, 7.5, 0, cl1};
> Point(7) = {5, 2.5, 0, cl1};
> Line(1) = {1, 2};
> Line(2) = {2, 3};
> Line(3) = {3, 4};
> Line(4) = {4, 1};
> Circle(5) = {6, 5, 7};
> Circle(6) = {7, 5, 6};
> Line Loop(1) = {1, 2, 3, 4, -6, -5};
> Plane Surface(1) = {1};
> Line Loop(2) = {5, 6};
> Plane Surface(2) = {2};
> Physical Line("inlet") = {1};
> Physical Line("outlet") = {3};
> Physical Line("wall") = {2, 4};
> Physical Surface("interstitial") = {1};
> Physical Surface("beadface") = {2};
>
>
>
> //////////////////////////////////////////////////////////    rec.cpp
> //////////////////////////////////////////////////////////////////////////////////
>  // A simple Gmsh API demonstration program.
> #include "Gmsh.h"
> #include "GModel.h"
> #include "MElement.h"
> #include "MVertex.h"
> #include <iostream>
>
> typedef   std::vector<GEdge *> Lineloop;
> typedef std::vector<Lineloop> Loops;
>
> void *addBead(GModel *m, Loops &l, double const &cx, double const &cy,
> double const &radius, double const &lc_bead) {
>   Lineloop b;
>   GVertex *gvc1c = m->addVertex(cx, cy, 0, lc_bead);
>   GVertex *gvc1s = m->addVertex(cx, cy - radius, 0, lc_bead);
>   GVertex *gvc1e = m->addVertex(cx, cy + radius, 0, lc_bead);
>   GEdge *gec11 = m->addCircleArcCenter(gvc1s, gvc1c, gvc1e);
>   GEdge *gec12 = m->addCircleArcCenter(gvc1e, gvc1c, gvc1s);
>
>   b.push_back(gec11);
>   b.push_back(gec12);
>   l.push_back(b);
> }
>
> int main(int argc, char **argv)
> {
>   // Initialization.
>   GmshInitialize(argc, argv);
>   // Options may be set this way.
>   // Output information messages generated by the Gmsh library.
>   GmshSetOption("General", "Terminal", 1.);
>   // Be verbose (output debug messages).
>   GmshSetOption("General", "Verbosity", 99.);
>   // Create GModel (the Gmsh library core) instance.
>   GModel *m = new GModel;
>   // Choices are "Gmsh" and "OCC" if the Gmsh library is compiled with
>   // OpenCASCADE. Usually you want to use the "Gmsh" factory.
>   m->setFactory("Gmsh");
>
>   // Add vertices. Equivalent .geo directives are
>   // cl1 = 0.1;
>   // Point(1) = {-1, -1, 0, cl1};
>   // Point(2) = {1, -1, 0, cl1};
>   // Point(3) = {1, 1, 0, cl1};
>   // Point(4) = {-1, 1, 0, cl1};
>   // Point(5) = {0, 0, 0, cl1};
>   const double lc_wall = 0.08, lc_bead = 0.08;
>
>   // generating walls
>   const double xmin = 10, xmax = -10, ymin = 10, ymax = -10, dx = 0.1, dy
> = 2;
>
>   // corner points of rect domain
>   GVertex *gv1 = m->addVertex(xmin - dx, ymin - dy, 0, lc_wall);
>   GVertex *gv2 = m->addVertex(xmax + dx, ymin - dy, 0, lc_wall);
>   GVertex *gv3 = m->addVertex(xmax + dx, ymax + dy, 0, lc_wall);
>   GVertex *gv4 = m->addVertex(xmin - dx, ymax + dy, 0, lc_wall);
>
>   // lines around the rect domain
>   GEdge *ge1 = m->addLine(gv1, gv2);
>   GEdge *ge2 = m->addLine(gv2, gv3);
>   GEdge *ge3 = m->addLine(gv3, gv4);
>   GEdge *ge4 = m->addLine(gv4, gv1);
>
>   // // draw circle
>
>   Loops ls;
>
>   // exterior boundary
>   Lineloop tmp;
>
>   tmp.push_back(ge1);
>   tmp.push_back(ge2);
>   tmp.push_back(ge3);
>   tmp.push_back(ge4);
>   ls.push_back(tmp);
>
>   // call the bead func
>   int nBeads = 1;
>   double radius = ymax / nBeads / 4;
>   double cx = xmin / 2, cy = ymin / 2;
>   for (int i = 0; i < nBeads; i++) {
>     addBead(m, ls, cx, cy, radius, lc_bead);
>     cx += 3 * radius;
>   }
>
>
>   // interstitial domain
>   GFace *gf1 = m->addPlanarFace(ls);
>
>   // create faces of beads
>   Loops::iterator it = ls.begin();
>   it++;
>   std::vector<GRegion *> fbeads;
>   Loops lst;
>   int pn_beadface = m->setPhysicalName(nf_bead, dim_face);
>   for (;it != ls.end(); it++) {
>     lst.push_back(*it);
>     GFace *gft = m->addPlanarFace(lst);
>     gft->addPhysicalEntity(pn_beadface);
>     lst.pop_back();
>   }
>
>   // The geometry constructed by the operations above may be saved this
> way.
>   m->writeGEO("test.geo");
>
>   // Create surface (2-D) mesh. Pass 3 to mesh() if creating a volume
>   // (3-D) mesh.
>   m->mesh(2);
>
>   // // The created mesh may be saved this way.
>   m->writeMSH("test.msh");
>
>
>
>   // Finalization.
>   delete m;
>   GmshFinalize();
> }
>
>
> --
> Kind regards,
> Guowei He
>
>


-- 
Kind regards,
Guowei He
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