# vtkVolumeExample

VTKExamples/Python//vtkVolumeExample

### Description

Volume render unstructured transient data.

### Code

vtkVolumeExample.py

    #!/usr/bin/env python
    from __future__ import print_function
    from vtk import *

    tse = vtkTimeSourceExample()
    ex = tse.GetExecutive()
    tse.UpdateInformation()

    #inspect available time range and time steps
    print(ex.GetOutputInformation())

    #make it grow because bounds are easy to inspect
    # tse.SetGrowing(1)

    ex.SetUpdateTimeStep(0,0.0)
    tse.Update()
    print(tse.GetOutput().GetBounds())

    #pick some other time inside the time range
    ex.SetUpdateTimeStep(0,0.5)
    tse.Update()
    print(tse.GetOutput().GetBounds())

    grid = tse.GetOutput()
    print(grid)

    tri = vtkDataSetTriangleFilter()
    tri.SetInputData(grid)
    tri.SetTetrahedraOnly(1)
    tri.Update()
    output = tri.GetOutput()

    iss = output.GetPointData().SetActiveScalars("Point Label")
    # iss = gridMapper.GetInput().GetCellData().SetActiveScalars(options.scalarName)
    assert(iss>-1)

    drange = [0, 1]

    # Create transfer mapping scalar value to opacity.
    opacityFunction = vtkPiecewiseFunction()
    opacityFunction.AddPoint(drange[0], 0.0)
    opacityFunction.AddPoint(drange[1], 1.0)

    # Create transfer mapping scalar value to color.
    colorFunction = vtkColorTransferFunction()
    colorFunction.SetColorSpaceToHSV()
    colorFunction.HSVWrapOff()
    colorFunction.AddRGBPoint(drange[0], 0.0, 0.0, 1.0)
    colorFunction.AddRGBPoint(drange[1], 1.0, 0.0, 0.0)

    volumeProperty = vtkVolumeProperty()
    volumeProperty.SetScalarOpacity(opacityFunction)
    volumeProperty.SetColor(colorFunction)
    volumeProperty.ShadeOff()
    volumeProperty.SetInterpolationTypeToLinear()
    # volumeProperty.SetScalarOpacityUnitDistance(options.unit)

    volumeMapper = vtkUnstructuredGridVolumeRayCastMapper()
    # volumeMapper = vtkUnstructuredGridVolumeZSweepMapper()
    # volumeMapper = vtkProjectedTetrahedraMapper()
    # volumeMapper.SetBlendModeToMaximumIntensity()
    volumeMapper.SetInputData(output)

    volume = vtkVolume()
    volume.SetMapper(volumeMapper)
    volume.SetProperty(volumeProperty)

    # create a rendering window and renderer
    renderer = vtkRenderer()
    renderer.SetBackground(0,0,0)

    window = vtkRenderWindow()
    window.SetSize(512,512)
    window.AddRenderer(renderer)

    interactor = vtkRenderWindowInteractor()
    interactor.SetRenderWindow(window)

    style = vtkInteractorStyleTrackballCamera();
    interactor.SetInteractorStyle(style);

    renderer.AddVolume(volume)

    scalarBar = vtkScalarBarActor()
    scalarBar.SetLookupTable(colorFunction);
    scalarBar.SetOrientationToVertical();
    scalarBar.SetPosition( 0.85, 0.7 );
    scalarBar.SetPosition2( 0.1, 0.3 );
    propT = vtkTextProperty()
    propL = vtkTextProperty()
    propT.SetFontFamilyToArial()
    propT.ItalicOff()
    propT.BoldOn()
    propL.BoldOff()
    scalarBar.SetTitleTextProperty(propT);
    scalarBar.SetLabelTextProperty(propL);
    scalarBar.SetLabelFormat("%5.2f")
    renderer.AddActor(scalarBar)

    # setup the text and add it to the window
    textActor = vtkTextActor()
    textActor.GetTextProperty().SetFontSize(12)
    textActor.SetPosition2(10, 40)
    renderer.AddActor2D(textActor)
    textActor.SetInput("time = ")
    textActor.GetTextProperty().SetColor(1.0,1.0,1.0)

    renderer.ResetCameraClippingRange()
    renderer.ResetCamera()

    counter = 1
    time = 0
    while time<=1:
        print("time = ", time)
        textActor.SetInput("time = %g" % time)

        window.Render()

        # TODO FIXME if this block is not here than the volume renders wrongly
        #renderer.RemoveVolume(volume)
        # del volume
        volume = vtkVolume()
        volume.SetMapper(volumeMapper)
        volume.SetProperty(volumeProperty)
        renderer.AddVolume(volume)

        counter = counter + 1
        time = time + 1./10
        ex.SetUpdateTimeStep(0,time)
        tse.Modified()
        if output.GetPointData().GetScalars():
            print(output.GetPointData().GetScalars().GetRange())
        # if grid.GetPointData().GetScalars():
        #   print(grid.GetPointData().GetScalars().GetRange())
        # print(grid.GetPointData().GetScalars())

    # while True:
        # window.Render()