CompassWidget

#!/usr/bin/env python3

import math
# noinspection PyUnresolvedReferences
import vtkmodules.vtkInteractionStyle
# noinspection PyUnresolvedReferences
import vtkmodules.vtkRenderingOpenGL2
from vtkmodules.vtkCommonCore import (
    VTK_VERSION_NUMBER,
    vtkCommand,
    vtkMath,
    vtkVersion
)
from vtkmodules.vtkCommonColor import vtkNamedColors
from vtkmodules.vtkRenderingAnnotation import vtkAnnotatedCubeActor
from vtkmodules.vtkInteractionStyle import vtkInteractorStyleTrackballCamera
from vtkmodules.vtkRenderingCore import (
    vtkRenderWindow,
    vtkRenderWindowInteractor,
    vtkRenderer
)

try:
    from vtkmodules.vtkInteractionWidgets import (
        vtkCompassRepresentation,
        vtkCompassWidget
    )
except:
    from vtkmodules.vtkGeovisCore import (
        vtkCompassRepresentation,
        vtkCompassWidget
    )

def vtk_version_ok(major, minor, build):
    """
    Check the VTK version.

    :param major: Major version.
    :param minor: Minor version.
    :param build: Build version.
    :return: True if the requested VTK version is greater or equal to the actual VTK version.
    """
    needed_version = 10000000000 * int(major) \
                     + 100000000 * int(minor) \
                     + int(build)
    try:
        vtk_version_number = VTK_VERSION_NUMBER
    except AttributeError:
        # Expand component-wise comparisons for VTK versions < 8.90.
        ver = vtkVersion()
        vtk_version_number = 10000000000 * ver.GetVTKMajorVersion() \
                             + 100000000 * ver.GetVTKMinorVersion() \
                             + ver.GetVTKBuildVersion()
    if vtk_version_number >= needed_version:
        return True
    else:
        return False

def CompassWidgetValueChangedCallback(widget, event):
    """
    Callback to set the camera position according to the position parameters given by the vtkCompassWidget.
    """
    try:
        camera = widget.GetCurrentRenderer().GetActiveCamera()
    except AttributeError:
        return

    # calculate new camera position from compass widget parameters
    distance = widget.GetDistance()
    tilt = widget.GetTilt()
    heading = widget.GetHeading()

    x = distance * math.cos(vtkMath.RadiansFromDegrees(heading)) * math.cos(vtkMath.RadiansFromDegrees(tilt))
    y = distance * math.sin(vtkMath.RadiansFromDegrees(heading)) * math.cos(vtkMath.RadiansFromDegrees(tilt))
    z = distance * math.sin(vtkMath.RadiansFromDegrees(tilt))

    camera.SetPosition(x, y, z)
    camera.SetFocalPoint(0, 0, 0)
    camera.SetViewUp(0, 0, 1)
    camera.SetClippingRange(0.1, distance + 1)

    widget.GetCurrentRenderer().Render()



def main():
    use_improved_compass_widget = vtk_version_ok(9, 2, 20220831)

    colors = vtkNamedColors()

    actor = vtkAnnotatedCubeActor()
    actor.GetCubeProperty().SetColor(colors.GetColor3d('PeachPuff'))

    # a renderer and render window
    renderer = vtkRenderer()
    renderWindow = vtkRenderWindow()
    renderWindow.AddRenderer(renderer)

    # an interactor
    renderWindowInteractor = vtkRenderWindowInteractor()
    renderWindowInteractor.SetRenderWindow(renderWindow)

    # create the widget and its representation
    compassRepresentation = vtkCompassRepresentation()

    compassWidget = vtkCompassWidget()
    compassWidget.SetInteractor(renderWindowInteractor)
    compassWidget.SetRepresentation(compassRepresentation)

    # add a callback to update the camera position on vtkCommand::WidgetValueChangedEvent
    compassWidget.AddObserver(vtkCommand.WidgetValueChangedEvent, CompassWidgetValueChangedCallback)

    if use_improved_compass_widget:
        compassRepresentation.SetMinimumDistance(2)
        compassRepresentation.SetMaximumDistance(10)
        compassWidget.SetDistance(5)
        compassWidget.SetTiltSpeed(45)
        compassWidget.SetDistanceSpeed(2)

    # add the actors to the scene
    renderer.AddActor(actor)
    renderer.SetBackground(colors.GetColor3d('MidnightBlue'))

    renderWindow.SetSize(640, 480)
    renderWindow.SetWindowName('CompassWidget')

    renderWindow.Render()
    compassWidget.EnabledOn()

    if use_improved_compass_widget:
        # no interactor style - camera is moved by widget callback
        renderWindowInteractor.SetInteractorStyle(None)
        # set camera to initial position
        compassWidget.InvokeEvent(vtkCommand.WidgetValueChangedEvent)

    # begin interaction
    renderWindowInteractor.Start()


if __name__ == '__main__':
    main()