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
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