Picking of 2D Actors in VTK-Python

2d-picking.py

import vtk

class CustomInteractor(vtk.vtkInteractorStyleTrackballCamera):

	def __init__(self, renderer, renWin):
		self.AddObserver('LeftButtonPressEvent', self.OnLeftButtonDown)
		self.AddObserver('LeftButtonReleaseEvent', self.OnLeftButtonRelease)
		self.AddObserver('MouseMoveEvent', self.OnMouseMove)

		self.renderer = renderer
		self.chosenPiece = None
		self.renWin = renWin

	def OnLeftButtonRelease(self, obj, eventType):
		self.chosenPiece = None
		vtk.vtkInteractorStyleTrackballCamera.OnLeftButtonUp(self)

	def OnLeftButtonDown(self, obj, eventType):
		clickPos = self.GetInteractor().GetEventPosition()

		picker = vtk.vtkPropPicker()
		picker.Pick(clickPos[0], clickPos[1], 0, self.renderer)
		actor = picker.GetActor2D()

		self.chosenPiece = actor

		vtk.vtkInteractorStyleTrackballCamera.OnLeftButtonDown(self)

	def OnMouseMove(self, obj, eventType):
		if self.chosenPiece is not None:

			mousePos = self.GetInteractor().GetEventPosition()

			self.chosenPiece.SetPosition(mousePos[0], mousePos[1])

			self.renWin.Render()
		else :
			vtk.vtkInteractorStyleTrackballCamera.OnMouseMove(self)


def buildDiskActor(inner_radius = 10, outer_radius = 20, position = (100, 20), color = (1, 1, 1)):
	disk = vtk.vtkDiskSource()
	disk.SetInnerRadius(inner_radius)
	disk.SetOuterRadius(outer_radius)
	disk.SetRadialResolution(100)
	disk.SetCircumferentialResolution(100)
	disk.Update()

	mapper = vtk.vtkPolyDataMapper2D()
	mapper.SetInputConnection(disk.GetOutputPort())

	actor = vtk.vtkActor2D()
	actor.SetMapper(mapper)

	actor.SetPosition(position[0], position[1])

	actor.GetProperty().SetColor(color)

	return actor

ren = vtk.vtkRenderer()
renWin = vtk.vtkRenderWindow()
renWin.AddRenderer(ren)
renWin.SetSize(600, 600)

elements = [
	buildDiskActor(position = (200, 400), color=(1, 0, 0)),
	buildDiskActor(position = (400, 400), color=(0, 1, 0)),
	buildDiskActor(position = (300, 200), color=(0, 0, 1)),
]

for actor in elements:
	ren.AddActor(actor)

iren = vtk.vtkRenderWindowInteractor()
iren.SetRenderWindow(renWin)
inStyle = CustomInteractor(ren, renWin)
iren.SetInteractorStyle(inStyle)

renWin.Render()
iren.Start()