BoxWidget

vtk-examples/PythonicAPI/Widgets/BoxWidget

Description¶

This example uses a vtkBoxWidget to manipulate an actor. The class includes geometry to draw a box around the object, which is bound to it via SetProp3D. The box is dimensioned using the SetPlaceFactor method, and positioned with the PlaceWidget method.

After the initial setup, synchronizing the box with the object is done through a custom callback class or function, which is passed to the box widget through the AddObserver method.

For a widget that isn't tied to a specific vtkProp3D and has its geometric representation separate from the interaction logic, see the example BoxWidget2.

Other languages

See (Cxx), (Python)

Question

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Code¶

BoxWidget.py

#!/usr/bin/env python3

# noinspection PyUnresolvedReferences
import vtkmodules.vtkInteractionStyle
# noinspection PyUnresolvedReferences
import vtkmodules.vtkRenderingOpenGL2
from vtkmodules.vtkCommonColor import vtkNamedColors
from vtkmodules.vtkCommonTransforms import vtkTransform
from vtkmodules.vtkFiltersSources import vtkConeSource
from vtkmodules.vtkInteractionWidgets import vtkBoxWidget
from vtkmodules.vtkRenderingCore import (
    vtkActor,
    vtkPolyDataMapper,
    vtkRenderWindow,
    vtkRenderWindowInteractor,
    vtkRenderer
)


def get_program_parameters():
    import argparse
    description = 'Demonstrate two ways of using callbacks.'
    epilogue = '''
    '''
    parser = argparse.ArgumentParser(description=description, epilog=epilogue,
                                     formatter_class=argparse.RawDescriptionHelpFormatter)
    parser.add_argument('-f', '--fn_cb', action='store_false',
                        help='Use a function callback instead of a class callback.')
    args = parser.parse_args()
    return args.fn_cb


def main():
    #  Decide what approach to use.
    use_class_callback = get_program_parameters()

    colors = vtkNamedColors()

    # Create a Cone
    cone = vtkConeSource(resolution=20)
    cone_mapper = vtkPolyDataMapper()
    cone >> cone_mapper
    cone_actor = vtkActor(mapper=cone_mapper)
    cone_actor.property.color = colors.GetColor3d('BurlyWood')

    # A renderer and render window.
    renderer = vtkRenderer(background=colors.GetColor3d('Blue'))
    renderer.AddActor(cone_actor)

    ren_win = vtkRenderWindow(window_name='BoxWidget')
    ren_win.AddRenderer(renderer)
    ren_win.SetWindowName('BoxWidget')

    # An interactor.
    interactor = vtkRenderWindowInteractor()
    interactor.render_window = ren_win

    # A Box widget
    # We use a place_factor of 1.25 to make the box 1.25x larger than the actor.
    box_widget = vtkBoxWidget(interactor=interactor, prop3d=cone_actor, place_factor=1.25)
    box_widget.PlaceWidget()
    box_widget.On()

    # Set up and register the callback with the object that it is observing.
    if use_class_callback:
        box_widget.AddObserver('InteractionEvent', BoxCallback())
        # Or:
        # box_callback = BoxCallback()
        # box_widget.AddObserver('InteractionEvent', box_callback)
    else:
        box_widget.AddObserver('EndInteractionEvent', box_callback)

    # Start
    interactor.Initialize()
    ren_win.Render()
    interactor.Start()


class BoxCallback:
    def __call__(self, caller, ev):
        # Just do this to demonstrate who called callback and the event that triggered it.
        # print(caller.class_name, 'Event Id:', ev)
        t = vtkTransform()
        caller.GetTransform(t)
        caller.prop3d.user_transform = t


def box_callback(obj, event):
    t = vtkTransform()
    obj.GetTransform(t)
    obj.prop3d.user_transform = t


if __name__ == '__main__':
    main()