# ------------------------------------------------------------------------------ # # Gmsh Python tutorial 4 # # Holes in surfaces, annotations, entity colors # # ------------------------------------------------------------------------------ import gmsh import math import sys import os gmsh.initialize() gmsh.model.add("t4") cm = 1e-02 e1 = 4.5 * cm e2 = 6 * cm / 2 e3 = 5 * cm / 2 h1 = 5 * cm h2 = 10 * cm h3 = 5 * cm h4 = 2 * cm h5 = 4.5 * cm R1 = 1 * cm R2 = 1.5 * cm r = 1 * cm Lc1 = 0.01 Lc2 = 0.003 def hypot(a, b): return math.sqrt(a * a + b * b) ccos = (-h5 * R1 + e2 * hypot(h5, hypot(e2, R1))) / (h5 * h5 + e2 * e2) ssin = math.sqrt(1 - ccos * ccos) # We start by defining some points and some lines. To make the code shorter we # can redefine a namespace: factory = gmsh.model.geo factory.addPoint(-e1 - e2, 0, 0, Lc1, 1) factory.addPoint(-e1 - e2, h1, 0, Lc1, 2) factory.addPoint(-e3 - r, h1, 0, Lc2, 3) factory.addPoint(-e3 - r, h1 + r, 0, Lc2, 4) factory.addPoint(-e3, h1 + r, 0, Lc2, 5) factory.addPoint(-e3, h1 + h2, 0, Lc1, 6) factory.addPoint(e3, h1 + h2, 0, Lc1, 7) factory.addPoint(e3, h1 + r, 0, Lc2, 8) factory.addPoint(e3 + r, h1 + r, 0, Lc2, 9) factory.addPoint(e3 + r, h1, 0, Lc2, 10) factory.addPoint(e1 + e2, h1, 0, Lc1, 11) factory.addPoint(e1 + e2, 0, 0, Lc1, 12) factory.addPoint(e2, 0, 0, Lc1, 13) factory.addPoint(R1 / ssin, h5 + R1 * ccos, 0, Lc2, 14) factory.addPoint(0, h5, 0, Lc2, 15) factory.addPoint(-R1 / ssin, h5 + R1 * ccos, 0, Lc2, 16) factory.addPoint(-e2, 0.0, 0, Lc1, 17) factory.addPoint(-R2, h1 + h3, 0, Lc2, 18) factory.addPoint(-R2, h1 + h3 + h4, 0, Lc2, 19) factory.addPoint(0, h1 + h3 + h4, 0, Lc2, 20) factory.addPoint(R2, h1 + h3 + h4, 0, Lc2, 21) factory.addPoint(R2, h1 + h3, 0, Lc2, 22) factory.addPoint(0, h1 + h3, 0, Lc2, 23) factory.addPoint(0, h1 + h3 + h4 + R2, 0, Lc2, 24) factory.addPoint(0, h1 + h3 - R2, 0, Lc2, 25) factory.addLine(1, 17, 1) factory.addLine(17, 16, 2) # Gmsh provides other curve primitives than straight lines: splines, B-splines, # circle arcs, ellipse arcs, etc. Here we define a new circle arc, starting at # point 14 and ending at point 16, with the circle's center being the point 15: factory.addCircleArc(14, 15, 16, 3) # Note that, in Gmsh, circle arcs should always be smaller than Pi. The # OpenCASCADE geometry kernel does not have this limitation. # We can then define additional lines and circles, as well as a new surface: factory.addLine(14, 13, 4) factory.addLine(13, 12, 5) factory.addLine(12, 11, 6) factory.addLine(11, 10, 7) factory.addCircleArc(8, 9, 10, 8) factory.addLine(8, 7, 9) factory.addLine(7, 6, 10) factory.addLine(6, 5, 11) factory.addCircleArc(3, 4, 5, 12) factory.addLine(3, 2, 13) factory.addLine(2, 1, 14) factory.addLine(18, 19, 15) factory.addCircleArc(21, 20, 24, 16) factory.addCircleArc(24, 20, 19, 17) factory.addCircleArc(18, 23, 25, 18) factory.addCircleArc(25, 23, 22, 19) factory.addLine(21, 22, 20) factory.addCurveLoop([17, -15, 18, 19, -20, 16], 21) factory.addPlaneSurface([21], 22) # But we still need to define the exterior surface. Since this surface has a # hole, its definition now requires two curves loops: factory.addCurveLoop([11, -12, 13, 14, 1, 2, -3, 4, 5, 6, 7, -8, 9, 10], 23) factory.addPlaneSurface([23, 21], 24) # As a general rule, if a surface has N holes, it is defined by N+1 curve loops: # the first loop defines the exterior boundary; the other loops define the # boundaries of the holes. factory.synchronize() # Finally, we can add some comments by creating a post-processing view # containing some strings: v = gmsh.view.add("comments") # Add a text string in window coordinates, 10 pixels from the left and 10 pixels # from the bottom: gmsh.view.addListDataString(v, [10, -10], ["Created with Gmsh"]) # Add a text string in model coordinates centered at (X,Y,Z) = (0, 0.11, 0), # with some style attributes: gmsh.view.addListDataString(v, [0, 0.11, 0], ["Hole"], ["Align", "Center", "Font", "Helvetica"]) # If a string starts with `file://', the rest is interpreted as an image # file. For 3D annotations, the size in model coordinates can be specified after # a `@' symbol in the form `widthxheight' (if one of `width' or `height' is # zero, natural scaling is used; if both are zero, original image dimensions in # pixels are used): png = os.path.join(os.path.dirname(os.path.abspath(__file__)), os.pardir, 't4_image.png') gmsh.view.addListDataString(v, [0, 0.09, 0], ["file://" + png + "@0.01x0"], ["Align", "Center"]) # The 3D orientation of the image can be specified by proving the direction # of the bottom and left edge of the image in model space: gmsh.view.addListDataString(v, [-0.01, 0.09, 0], ["file://" + png + "@0.01x0,0,0,1,0,1,0"]) # The image can also be drawn in "billboard" mode, i.e. always parallel to # the camera, by using the `#' symbol: gmsh.view.addListDataString(v, [0, 0.12, 0], ["file://" + png + "@0.01x0#"], ["Align", "Center"]) # The size of 2D annotations is given directly in pixels: gmsh.view.addListDataString(v, [150, -7], ["file://" + png + "@20x0"]) # These annotations are handled by a list-based post-processing view. For # large post-processing datasets, that contain actual field values defined on # a mesh, you should use model-based post-processing views instead, which # allow to efficiently store continuous or discontinuous scalar, vector and # tensor fields, or arbitrary polynomial order. # Views and geometrical entities can be made to respond to double-click # events, here to print some messages to the console: gmsh.view.option.setString(v, "DoubleClickedCommand", "Printf('View[0] has been double-clicked!');") gmsh.option.setString( "Geometry.DoubleClickedLineCommand", "Printf('Curve %g has been double-clicked!', " "Geometry.DoubleClickedEntityTag);") # We can also change the color of some entities: gmsh.model.setColor([(2, 22)], 127, 127, 127) # Gray50 gmsh.model.setColor([(2, 24)], 160, 32, 240) # Purple gmsh.model.setColor([(1, i) for i in range(1, 15)], 255, 0, 0) # Red gmsh.model.setColor([(1, i) for i in range(15, 21)], 255, 255, 0) # Yellow gmsh.model.mesh.generate(2) gmsh.write("t4.msh") # Launch the GUI to see the results: if '-nopopup' not in sys.argv: gmsh.fltk.run() gmsh.finalize()