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StippledLine

vtk-examples/Python/Rendering/StippledLine

Description

VTK OpenGL2 no longer supports Stippled Lines. This example uses texture mapping to created stippled lines. Two parameters, StipplePattern and StippleRepeat, control the pattern of the stippled lines.

StipplePattern is a 16-bit binary pattern, 1 = pixel on, 0 = pixel off.

StippleRepeat is the stippling repeat factor of a Line, which specifies how many times each bit in the pattern is to be repeated.

It can be tricky to set the proper pattern and repeat, so experiment.

Other languages

See (Cxx)

Question

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Code

StippledLine.py

#!/usr/bin/env python

import vtk


def main():
    colors = vtk.vtkNamedColors()

    lines = vtk.vtkLineSource()
    # Create two points, P0 and P1
    p0 = [1.0, 0.0, 0.0]
    p1 = [5.0, 0.0, 0.0]

    lines.SetResolution(11)
    lines.SetPoint1(p0)
    lines.SetPoint2(p1)
    lines.Update()
    mapper = vtk.vtkPolyDataMapper()
    mapper.SetInputConnection(lines.GetOutputPort())

    actor = vtk.vtkActor()
    actor.SetMapper(mapper)
    actor.GetProperty().SetLineWidth(5)
    actor.GetProperty().SetColor(colors.GetColor3d("Banana"))

    StippledLine(actor, 0xA1A1, 2)

    ren1 = vtk.vtkRenderer()
    ren1.SetBackground(colors.GetColor3d("SlateGray"))
    renWin = vtk.vtkRenderWindow()
    renWin.SetSize(640, 480)
    renWin.SetWindowName('StippledLine')


    renWin.AddRenderer(ren1)
    iren = vtk.vtkRenderWindowInteractor()
    iren.SetRenderWindow(renWin)
    ren1.AddActor(actor)
    renWin.Render()
    iren.Start()


def StippledLine(actor, lineStipplePattern, lineStippleRepeat):
    tcoords = vtk.vtkDoubleArray()
    image = vtk.vtkImageData()
    texture = vtk.vtkTexture()

    # Create texture
    dimension = 16 * lineStippleRepeat

    image.SetDimensions(dimension, 1, 1)
    image.AllocateScalars(vtk.VTK_UNSIGNED_CHAR, 4)
    image.SetExtent(0, dimension - 1, 0, 0, 0, 0)
    on = 255
    off = 0
    i_dim = 0
    while i_dim < dimension:
        for i in range(0, 16):
            mask = (1 << i)
            bit = (lineStipplePattern & mask) >> i
            value = bit
            if value == 0:
                for j in range(0, lineStippleRepeat):
                    image.SetScalarComponentFromFloat(i_dim, 0, 0, 0, on)
                    image.SetScalarComponentFromFloat(i_dim, 0, 0, 1, on)
                    image.SetScalarComponentFromFloat(i_dim, 0, 0, 2, on)
                    image.SetScalarComponentFromFloat(i_dim, 0, 0, 3, off)
                    i_dim += 1
            else:
                for j in range(0, lineStippleRepeat):
                    image.SetScalarComponentFromFloat(i_dim, 0, 0, 0, on)
                    image.SetScalarComponentFromFloat(i_dim, 0, 0, 1, on)
                    image.SetScalarComponentFromFloat(i_dim, 0, 0, 2, on)
                    image.SetScalarComponentFromFloat(i_dim, 0, 0, 3, on)
                    i_dim += 1
    polyData = actor.GetMapper().GetInput()
    # Create texture coordinates
    tcoords.SetNumberOfComponents(1)
    tcoords.SetNumberOfTuples(polyData.GetNumberOfPoints())
    for i in range(0, polyData.GetNumberOfPoints()):
        value = i * 0.5
        tcoords.SetTypedTuple(i, [value])
    polyData.GetPointData().SetTCoords(tcoords)
    texture.SetInputData(image)
    texture.InterpolateOff()
    texture.RepeatOn()

    actor.SetTexture(texture)


if __name__ == '__main__':
    main()