[vtkusers] change ploydata color using vtk.vtkUnsignedCharArray dynamically not re-rendering

[David E DeMarle]

Hi Ahishek,

It looks to me like you are appending to the end of the self.colors. Call
self.colors.GetNumberOfTuples() to verify that.
If you fix (do replacement with Insertvalue(id, value) instead of
InserNextValue(value)) I think it will do what you are trying to do.

hth




David E DeMarle
Kitware, Inc.
Principal Engineer
21 Corporate Drive
Clifton Park, NY 12065-8662
Phone: 518-881-4909

On Mon, Jun 4, 2018 at 8:35 PM, Abhishek <abhishekworld at gmail.com> wrote:

> Greetings,
> I am new to VTK so may be my question is very basic.
>
> I have following code, where the aim is to be able to change the lines
> colors using dynamically based on data we get from QColorDialog. if I
> apply the color directly to vtkActor and re-render the window then it
> just works fine. But eventually I wan to be able to change individual line
> Points color and thats why I am setting self.linesPolyData.
> GetCellData().SetScalars(self.colors) when I change the color using
> QPushButton in function def select_color(self): it doesn't re-render the
> lines with new color. What am I doing wrong?
>
> from Analysis.Channel import *import vtkimport numpy as npimport itertoolsimport sysimport math
> from PyQt5 import QtGui, QtCorefrom PyQt5.QtWidgets import QApplication, QWidget, QGridLayout, QScrollArea, QPushButton, QColorDialogfrom vtk.qt.QVTKRenderWindowInteractor import QVTKRenderWindowInteractor
>
>
> # Qt Class which will render the objectsclass MainWindow(QWidget):
>     def __init__(self, parent = None):
>         super().__init__()
>         self.layout = QGridLayout(self)
>         self.color_button = QPushButton('Select Color')
>
>         self.layout.addWidget(self.color_button)
>         self.color_button.clicked.connect(self.select_color)
>
>         self.color = [255, 255, 0, 255]
>         self.colors = vtk.vtkUnsignedCharArray()
>         self.colors.SetNumberOfComponents(4)
>
>         # Create the polydata where we will store all the geometric data
>         self.linesPolyData = vtk.vtkPolyData()
>
>         # Create three points
>         origin = [0.0, 0.0, 0.0]
>         p0 = [1.0, 0.0, 0.0]
>         p1 = [0.0, 1.0, 0.0]
>
>         # Create a vtkPoints container and store the points in it
>         pts = vtk.vtkPoints()
>         pts.InsertNextPoint(origin)
>         pts.InsertNextPoint(p0)
>         pts.InsertNextPoint(p1)
>
>         self.linesPolyData.SetPoints(pts)
>
>         # Create the first line (between Origin and P0)
>         line0 = vtk.vtkLine()
>         line0.GetPointIds().SetId(0, 0)  # the second 0 is the index of the Origin in linesPolyData's points
>         line0.GetPointIds().SetId(1, 1)  # the second 1 is the index of P0 in linesPolyData's points
>
>         # Create the second line (between Origin and P1)
>         line1 = vtk.vtkLine()
>         line1.GetPointIds().SetId(0, 0)  # the second 0 is the index of the Origin in linesPolyData's points
>         line1.GetPointIds().SetId(1, 2)  # 2 is the index of P1 in linesPolyData's points
>
>         self.lines = vtk.vtkCellArray()
>         self.lines.InsertNextCell(line0)
>         self.lines.InsertNextCell(line1)
>         # Add the lines to the polydata container
>         self.linesPolyData.SetLines(self.lines)
>
>         for i in range(0, self.lines.GetNumberOfCells()):
>             self.colors.InsertNextTuple(self.color)
>
>         self.linesPolyData.GetCellData().SetScalars(self.colors)
>
>         self.mapper = vtk.vtkPolyDataMapper()
>         self.mapper.SetInputData(self.linesPolyData)
>
>         self.actor = vtk.vtkActor()
>         self.actor.SetMapper(self.mapper)
>         self.actor.GetProperty().SetLineWidth(4)
>
>         self.vtk_widget = QVTKRenderWindowInteractor()
>         # vtk_widget.setMinimumSize(round(1024/3), round(1024/3))
>         ren = vtk.vtkRenderer()
>         self.vtk_widget.GetRenderWindow().AddRenderer(ren)
>
>         ren.AddActor(self.actor)
>
>         ren.ResetCamera()
>         interactor = self.vtk_widget.GetRenderWindow().GetInteractor()
>         interactor.Initialize()
>         interactor.Start()
>
>         self.layout.addWidget(self.vtk_widget)
>
>     def select_color(self):
>         color = QColorDialog.getColor(QtCore.Qt.green, self)
>         if color.isValid():
>             self.color = color.getRgb()
>             for i in range(0, self.lines.GetNumberOfCells()):
>                 self.colors.InsertNextTuple(self.color)
>
>             self.linesPolyData.GetCellData().SetScalars(self.colors)
>             self.mapper.SetInputData(self.linesPolyData)
>             self.linesPolyData.Modified()
>             self.mapper.Modified()
>             # self.actor.GetProperty().Modified()
>             self.vtk_widget.Render()
>
>
> if __name__ == '__main__':
>     app = QApplication(sys.argv)
>     win = MainWindow()
>     win.show()
>     sys.exit(app.exec_())
>
> --
>
> Abhishek
>
> zeroth.me
>
> --
> Abhishek Patil
> zeroth.me
>
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