Viewer Example

Example of using Viewer

• Python

  Note

  Python API version 3 and later

  import os
  import sys
   
  from meshlib import mrmeshpy as mm
  from meshlib import mrviewerpy as mv
   
  # This example needs an input mesh; create one if you do not have it already
  if not os.path.exists("mesh.stl"):
      mm.saveMesh(mm.makeCube(), "mesh.stl")
   
  # The Viewer needs a graphical session. On a headless Linux machine (container, CI,
  # WSL without an X server, SSH without X forwarding) no window can be opened, and in
  # releases before 3.1.3.566 the failure was silent and the next viewer call hung forever.
  if sys.platform.startswith("linux") and not (os.environ.get("DISPLAY") or os.environ.get("WAYLAND_DISPLAY")):
      sys.exit("MeshLib Viewer requires a graphical session, but no display was found "
               "(neither DISPLAY nor WAYLAND_DISPLAY is set). "
               "On a headless machine start with the mesh loading and saving example "
               "(MeshLoadSave.dox.py) instead.")
   
  # Load mesh
  mesh = mm.loadMesh("mesh.stl")
   
  # Setup parameters
  params = mm.OffsetParameters()
  params.voxelSize = mesh.computeBoundingBox().diagonal() * 5e-3  # offset grid precision (algorithm is voxel based)
  if mm.findRightBoundary(mesh.topology).empty():
      params.signDetectionMode = mm.SignDetectionMode.HoleWindingRule  # use if you have holes in mesh
   
  # Make offset mesh
  offset = mesh.computeBoundingBox().diagonal() * 0.05
  result_mesh = mm.offsetMesh(mesh, offset, params)
   
   
  # Open a window; raises where the Viewer is unavailable, e.g. on macOS
  try:
      mv.launch()
  except RuntimeError as e:
      sys.exit(f"Could not start MeshLib Viewer: {e}")
   
  mv.addMeshToScene(mesh, "Mesh 1") # show initial mesh
  mv.Viewer().preciseFitDataViewport() # fit viewer to the mesh
  mv.selectByName("Mesh 1")
   
  mv.Viewer().preciseFitDataViewport() # fit viewer to the mesh
  mv.Viewer().showSceneTree(True) # enables Scene Tree in Viewer window
  # user can manipulate with viewer window while this python is on pause
  input("Press Enter to continue...")
   
  # remove all objects from scene
  mv.clearScene()
   
  # add offset mesh to scene
  mv.addMeshToScene(result_mesh, "Mesh Offset")
  mv.selectByName("Mesh Offset")
  mv.Viewer().showSceneTree(False) # disables Scene Tree in Viewer window
  # user can manipulate with viewer window while this python is on pause
  input("Press Enter to continue...")
   
  # close viewer window nicely
  mv.Viewer().shutdown()

  Viewer with scene tree
  
  Viewer without scene tree
  

  Note

  This example does not work on macOS: mv.launch() raises RuntimeError: MeshLib Viewer is not supported on macOS yet. In releases before 3.1.3.566 it terminated the Python process instead (SIGTRAP, exit code 133, no exception raised).