CODEWITHSUNDEEP
pythonc++stlvtk
C. Mihai
C. Mihai

Reputation: 51

Updating vtkPolyData from vtkActor

I'm pretty new to VTK. I'm trying to use VTK in python to edit a .stl file using the vtkBoxWidget. I'm reading the .stl file, editing it with the vtkBoxWidget by using the mouse/drag in the window interactor and in the end I want to write the new data to a new .stl when hitting a certain key.

Here's a code to demonstrate the issue:

#!/usr/bin/env python

import vtk
import sys
import os

filename = "file.stl"
# render the data
reader = vtk.vtkSTLReader()
reader.SetFileName(filename)

stlMapper = vtk.vtkPolyDataMapper()
stlMapper.SetInputConnection(reader.GetOutputPort())

# create an actor for our scene

stlActor = vtk.vtkActor()
stlActor.SetMapper(stlMapper)



ren = vtk.vtkRenderer()
renWin = vtk.vtkRenderWindow()
renWin.AddRenderer(ren)
iren = vtk.vtkRenderWindowInteractor()
iren.SetRenderWindow(renWin)

# The box widget observes the events invoked by the render window
# interactor.  These events come from user interaction in the render
# window.
boxWidget = vtk.vtkBoxWidget()
boxWidget.SetInteractor(iren)
boxWidget.SetPlaceFactor(1.25)

# Add the actors to the renderer, set the background and window size.
ren.AddActor(stlActor)
ren.SetBackground(0.1, 0.2, 0.4)
renWin.SetSize(300, 300)

# As the box widget is interacted with, it produces a transformation
# matrix that is set on the actor.
t = vtk.vtkTransform()
def TransformActor(obj, event):
    global t, stlActor
    obj.GetTransform(t)
    stlActor.SetUserTransform(t)

def onKeyPressEvent(self, renderer):
    key = self.GetKeyCode()
    if(key=='l'):
        print stlActor.GetBounds()
        if(os.path.isfile("done.stl")==1):
                    os.remove("done.stl")
        print stlActor.GetMapper().GetInput().GetBounds()
        stlPolyData = stlActor.GetMapper().GetInput()
        writer = vtk.vtkSTLWriter()
        writer.SetFileName("done.stl")
        writer.AddInputDataObject(stlPolyData)
        writer.Write()
# Place the interactor initially. The actor is used to place and scale
# the interactor. An observer is added to the box widget to watch for
# interaction events. This event is captured and used to set the
# transformation matrix of the actor.
boxWidget.SetProp3D(stlActor)
boxWidget.PlaceWidget()
boxWidget.AddObserver("InteractionEvent", TransformActor)
iren.AddObserver('KeyPressEvent', onKeyPressEvent)

iren.Initialize()
renWin.Render()
iren.Start()

The problem is that I have no idea how to update the vtkPolyData or pass the transformations I applied to vtkActor to the vtkPolyData. In the code above, I tested this with the .GetBounds() in the two print functions. Originally the object had Bounds:

(-2.0, 2.0, 0.0, 1.625, -1.5, 1.8125)

After updating, the actor Bounds changed, but I can't pass all those properties to the vtkPolyData.

(-2.1331110248939638, 2.246371570191821, -1.5743578447908013, 2.5817210301577385, -2.1311284932847796, 2.0695034726591715)
(-2.0, 2.0, 0.0, 1.625, -1.5, 1.8125)

Thanks!

Upvotes: 1

Views: 3893

Answers (1)

C. Mihai
C. Mihai

Reputation: 51

I think I figured it:

def transformPolyData(actor):
    polyData = vtk.vtkPolyData()
    polyData.DeepCopy(actor.GetMapper().GetInput())
    transform = vtk.vtkTransform()
    transform.SetMatrix(actor.GetMatrix())
    fil = vtk.vtkTransformPolyDataFilter()
    fil.SetTransform(transform)
    fil.SetInputDataObject(polyData)
    fil.Update()
    polyData.DeepCopy(fil.GetOutput())
    return polyData;

That will transform the polyData to what I needed before saving.

Upvotes: 3

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