[vtkusers] vtkCellPicker failing to pick vtkPolyLine (using Python and wx)

[David vanEe]

Hi all,

I've recently updated my VTK from 5.4 to 5.10.1, and some old vtkCellPicker code isn't doing what I want anymore.  This 'simple' example works fine in 5.4 (both the blue and red actor highlight when you mouse-over them), but in 5.10.1 only the blue (quad) actor works.  The only difference between the two actors (aside from coordinates and colors) is the cellType of vtk.VTK_POLY_LINE vs vtk.VTK_QUAD.

I've tried looking for changes in the pick routine, but vtkCellPicker.cxx has undergone substantial changes and I was unable to locate the cause.  Any suggestions for getting the picker to pick the polyline?

Thanks in advance,
Dave


import wx
import vtk

from vtk.wx.wxVTKRenderWindowInteractor import wxVTKRenderWindowInteractor

class myVTKInteractor(wxVTKRenderWindowInteractor):
    def __init__(self, parent):
        wxVTKRenderWindowInteractor.__init__(self, parent, -1)

        self.Enable(1)
        self.AddObserver("ExitEvent", lambda o,e,f=self: f.Close())

        self.ren = vtk.vtkRenderer()
        self.GetRenderWindow().AddRenderer(self.ren)

        # simple point coords used by both actors
        coords = [(0.0, 0.0),
                  (1.0, 0.0),
                  (1.0, 1.0),
                  (0.0, 1.0)]

        self.actorData = [(1.0, vtk.VTK_POLY_LINE, (0.5,0.0,0.0), (1.0, 0.0, 0.0)),
                          (0.0, vtk.VTK_QUAD, (0.0, 0.0, 0.5), (0.0, 0.0, 1.0))]

        self.actorList = []
        for data in self.actorData:
            (zValue, cellType, dimColor, brightColor) = data

            points = vtk.vtkPoints()
            for (pointIndex, coord) in enumerate(coords):
                points.InsertPoint(pointIndex, coord[0], coord[1], zValue)

            idList = vtk.vtkIdList()
            idList.SetNumberOfIds(len(coords))
            for pointIndex in range(len(coords)):
                idList.SetId(pointIndex, pointIndex)
            cells = vtk.vtkCellArray()
            cells.InsertNextCell(idList)

            grid = vtk.vtkUnstructuredGrid()
            grid.SetPoints(points)
            grid.SetCells(cellType, cells)

            mapper = vtk.vtkDataSetMapper()
            mapper.SetInput(grid)

            actor = vtk.vtkActor()
            actor.SetMapper(mapper)
            actor.GetProperty().SetRepresentation(1)
            actor.GetProperty().SetLineWidth(5.0)
            actor.GetProperty().SetDiffuseColor(*dimColor)

            self.ren.AddActor(actor)
            self.actorList.append(actor)

        self.cellPicker = vtk.vtkCellPicker()


    def OnMotion(self, event):

        # invert Y value
        actualY = self.ren.GetSize()[1] - event.GetY()

        # dim all actors
        for (index, actor) in enumerate(self.actorList):
            (zValue, cellType, dimColor, brightColor) = self.actorData[index]
            actor.GetProperty().SetDiffuseColor(*dimColor)

        self.cellPicker.Pick(event.GetX(), actualY, 0, self.ren)
        dataSet = self.cellPicker.GetDataSet()

        if dataSet is not None:
            # highlight picked actor
            for (index, actor) in enumerate(self.actorList):
                if actor.GetMapper().GetInput() == dataSet:
                    (zOffset, cellType, dimColor, brightColor) = self.actorData[index]
                    actor.GetProperty().SetDiffuseColor(*brightColor)

        self.Render()


def wxVTKRenderWindowInteractorExample():
    app = wx.PySimpleApp()

    frame = wx.Frame(None, -1, "wxVTKRenderWindowInteractor", size=(400,400))

    widget = myVTKInteractor(frame)
    sizer = wx.BoxSizer(wx.VERTICAL)
    sizer.Add(widget, 1, wx.EXPAND)
    frame.SetSizer(sizer)
    frame.Layout()

    frame.Show()

    app.MainLoop()

if __name__ == "__main__":
    wxVTKRenderWindowInteractorExample()



--
David A. Van Ee, BASc, EIT
Convergent Manufacturing Technologies Inc.
6190 Agronomy Rd, Suite 403
Vancouver BC Canada V6T 1Z3

Email: david.vanee at convergent.ca<mailto:david.vanee at convergent.ca> | Tel: 604-822-9682 x103
WWW: http://www.convergent.ca<http://www.convergent.ca/> | Fax: 604-822-9659

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