# ------------------------------------------------------------------------------ # # Gmsh Python tutorial 8 # # Post-processing, image export and animations # # ------------------------------------------------------------------------------ import gmsh import os import sys # In addition to creating geometries and meshes, the Python API can also be used # to manipulate post-processing datasets (called "views" in Gmsh). gmsh.initialize() # We first create a simple geometry lc = 1e-2 gmsh.model.geo.addPoint(0, 0, 0, lc, 1) gmsh.model.geo.addPoint(.1, 0, 0, lc, 2) gmsh.model.geo.addPoint(.1, .3, 0, lc, 3) gmsh.model.geo.addPoint(0, .3, 0, lc, 4) gmsh.model.geo.addLine(1, 2, 1) gmsh.model.geo.addLine(3, 2, 2) gmsh.model.geo.addLine(3, 4, 3) gmsh.model.geo.addLine(4, 1, 4) gmsh.model.geo.addCurveLoop([4, 1, -2, 3], 1) gmsh.model.geo.addPlaneSurface([1], 1) gmsh.model.geo.synchronize() # We merge some post-processing views to work on path = os.path.dirname(os.path.abspath(__file__)) gmsh.merge(os.path.join(path, os.pardir, 'view1.pos')) gmsh.merge(os.path.join(path, os.pardir, 'view1.pos')) gmsh.merge(os.path.join(path, os.pardir, 'view4.pos')) # contains 2 views inside # Gmsh can read post-processing views in various formats. Here the `view1.pos' # and `view4.pos' files are in the Gmsh "parsed" format, which is interpreted by # the GEO script parser. The parsed format should only be used for relatively # small datasets of course: for larger datasets using e.g. MSH files is much # more efficient. Post-processing views can also be created directly from the # Python API. # We then set some general options: gmsh.option.setNumber("General.Trackball", 0) gmsh.option.setNumber("General.RotationX", 0) gmsh.option.setNumber("General.RotationY", 0) gmsh.option.setNumber("General.RotationZ", 0) white = (255, 255, 255) black = (0, 0, 0) # Color options are special # Setting a color option of "X.Y" actually sets the option "X.Color.Y" # Sets "General.Color.Background", etc. gmsh.option.setColor("General.Background", white[0], white[1], white[2]) gmsh.option.setColor("General.Foreground", black[0], black[1], black[2]) gmsh.option.setColor("General.Text", black[0], black[1], black[2]) gmsh.option.setNumber("General.Orthographic", 0) gmsh.option.setNumber("General.Axes", 0) gmsh.option.setNumber("General.SmallAxes", 0) # Show the GUI: if '-nopopup' not in sys.argv: gmsh.fltk.initialize() # We also set some options for each post-processing view: # If we were to follow the geo example blindly, we would read the number of # views from the relevant option value, and use the gmsh.option.setNumber() and # gmsh.option.setString() functions. A nicer way is to use gmsh.view.getTags() # and to use the gmsh.view.option.setNumber() and gmsh.view.option.setString() # functions. v = gmsh.view.getTags() if len(v) != 4: gmsh.logger.write("Wrong number of views!", "error") gmsh.finalize() exit() # We set some options for each post-processing view: gmsh.view.option.setNumber(v[0], "IntervalsType", 2) gmsh.view.option.setNumber(v[0], "OffsetZ", 0.05) gmsh.view.option.setNumber(v[0], "RaiseZ", 0) gmsh.view.option.setNumber(v[0], "Light", 1) gmsh.view.option.setNumber(v[0], "ShowScale", 0) gmsh.view.option.setNumber(v[0], "SmoothNormals", 1) gmsh.view.option.setNumber(v[1], "IntervalsType", 1) # Note that we can't yet set the ColorTable in API gmsh.view.option.setNumber(v[1], "NbIso", 10) gmsh.view.option.setNumber(v[1], "ShowScale", 0) gmsh.view.option.setString(v[2], "Name", "Test...") gmsh.view.option.setNumber(v[2], "Axes", 1) gmsh.view.option.setNumber(v[2], "IntervalsType", 2) gmsh.view.option.setNumber(v[2], "Type", 2) gmsh.view.option.setNumber(v[2], "IntervalsType", 2) gmsh.view.option.setNumber(v[2], "AutoPosition", 0) gmsh.view.option.setNumber(v[2], "PositionX", 85) gmsh.view.option.setNumber(v[2], "PositionY", 50) gmsh.view.option.setNumber(v[2], "Width", 200) gmsh.view.option.setNumber(v[2], "Height", 130) gmsh.view.option.setNumber(v[3], "Visible", 0) # You can save an MPEG movie directly by selecting `File->Export' in the # GUI. Several predefined animations are setup, for looping on all the time # steps in views, or for looping between views. # But the API can be used to build much more complex animations, by changing # options at run-time and re-rendering the graphics. Each frame can then be # saved to disk as an image, and multiple frames can be encoded to form a # movie. Below is an example of such a custom animation. t = 0 # Initial step for num in range(1, 4): # Set time step for vv in v: gmsh.view.option.setNumber(vv, "TimeStep", t) current_step = gmsh.view.option.getNumber(v[0], "TimeStep") max_step = gmsh.view.option.getNumber(v[0], "NbTimeStep") - 1 if current_step < max_step: t = t + 1 else: t = 0 gmsh.view.option.setNumber(v[0], "RaiseZ", gmsh.view.option.getNumber(v[0], "RaiseZ") + 0.01 / gmsh.view.option.getNumber(v[0], "Max") * t) if num == 3: # Resize the graphics when num == 3, to create 640x480 frames gmsh.option.setNumber("General.GraphicsWidth", gmsh.option.getNumber("General.MenuWidth") + 640) gmsh.option.setNumber("General.GraphicsHeight", 480) frames = 50 for num2 in range(frames): # Incrementally rotate the scene gmsh.option.setNumber("General.RotationX", gmsh.option.getNumber("General.RotationX") + 10) gmsh.option.setNumber("General.RotationY", gmsh.option.getNumber("General.RotationX") / 3) gmsh.option.setNumber("General.RotationZ", gmsh.option.getNumber("General.RotationZ") + 0.1) # Draw the scene gmsh.graphics.draw() if num == 3: # Uncomment the following lines to save each frame to an image file # gmsh.write("t8-{}.gif".format(num2)) # gmsh.write("t8-{}.ppm".format(num2)) # gmsh.write("t8-{}.jpg".format(num2)) pass if num == 3: # Here we could make a system call to generate a movie. For example, # with ffmeg: # import subprocess # subprocess.call("ffmpeg -i t8-%d.jpg t8.mpg".split(' ')) pass if '-nopopup' not in sys.argv: gmsh.fltk.run() gmsh.finalize()