Visualizer missing functionality and updates

[cmower]

Currently the following are missing from the visualizer

• the link names should be optionally displayed
• currently the user can visualize the robot links, but cannot customize their properties
• move functions like

  optas/optas/visualize.py

  Lines 19 to 51 in 17f1a18

  	def line(start, end, rgb, alpha, linewidth):
  	points = vtk.vtkPoints()
  	points.InsertNextPoint(*start)
  	points.InsertNextPoint(*end)
  	line = vtk.vtkLine()
  	line.GetPointIds().SetId(0, 0)
  	line.GetPointIds().SetId(0, 1)
  	lines = vtk.vtkCellArray()
  	lines.InsertNextCell(line)
  	polydata = vtk.vtkPolyData()
  	polydata.SetPoints(points)
  	polydata.SetLines(lines)
  	mapper = vtk.vtkPolyDataMapper()
  	mapper.SetInputData(polydata)
  	actor = vtk.vtkActor()
  	actor.SetMapper(mapper)
  	actor.GetProperty().SetLineWidth(linewidth)
  	if isinstance(rgb, list):
  	assert len(rgb) == 3, f"rgb is incorrect length, got {len(rgb)} expected 3"
  	actor.GetProperty().SetColor(*rgb)
  	if alpha < 1.0:
  	assert alpha >= 0.0, "the scalar alpha must be in the range [0, 1]"
  	actor.GetProperty().SetOpacity(alpha)
  	return actor

  into the main visualizer class, see #106
• in

  optas/optas/visualize.py

  Lines 622 to 654 in 17f1a18

  	if urdf_link.visual is None:
  	continue
  	material = urdf_link.visual.material
  	rgb = None
  	if isinstance(material.name, str) and material.name in material_names:
  	rgba = get_material_rgba(urdf_link.visual.material.name)
  	rgb = rgba[:3]
  	if isinstance(geometry, Mesh):
  	if geometry.filename.lower().endswith(".stl"):
  	filename = geometry.filename
  	if not os.path.exists(filename):
  	relpath = robot_model.get_urdf_dirname()
  	filename = os.path.join(relpath, filename)
  	scale = None
  	if geometry.scale is not None:
  	scale = geometry.scale
  	actors.append(
  	stl(
  	filename,
  	scale=scale,
  	rgb=rgb,
  	alpha=alpha,
  	position=position,
  	orientation=orientation,
  	euler_seq="xyz",
  	euler_degrees=True,
  	)
  	)

  we potentially miss out other visuals, need to iterate over urdf_link.visuals.
• Add documentation to visualize.py