[vtkusers] using vtkClipClosedSurface() on a box crashes

[David Gobbi]

Hi Kent,

Your code for building the polydata looks suspicious.  If you put your box
polydata directly into the mapper (i.e. without vtkClipClosedSurface) does
it display properly?

I translated your code into python (I'm not much of a Java programmer), and
it ran without any errors:


from vtk import *

points = [
  0.0, 0.0, 0.0,
  1.0, 0.0, 0.0,
  1.0, 1.0, 0.0,
  0.0, 1.0, 0.0,
  0.0, 0.0, 1.0,
  1.0, 0.0, 1.0,
  1.0, 1.0, 1.0,
  0.0, 1.0, 1.0,
]

seq = [
  4, 0,1,2,3,
  4, 1,5,6,2,
  4, 5,4,7,6,
  4, 4,0,3,7,
  4, 0,1,5,4,
  4, 3,2,6,7
]

# create a plane for clipping
plane = vtkPlane();
plane.SetOrigin(0.0, 0.0, 0.5);
plane.SetNormal(0, 0, 1);

# create the box from points and sequence
polyData = vtkPolyData();
pts = vtkPoints();
for i in range(8):
    pts.InsertNextPoint(points[i*3:(i+1)*3])
polyData.SetPoints(pts);
cells = vtkCellArray();
for i in range(6):
    cells.InsertNextCell(4)
    for j in range(1,5):
        cells.InsertCellPoint(seq[5*i + j])
polyData.SetPolys(cells);

clipClosedSurface = vtkClipClosedSurface();
planes = vtkPlaneCollection();
planes.AddItem(plane);
clipClosedSurface.SetClippingPlanes(planes);
clipClosedSurface.AddInputData(polyData);
clipClosedSurface.Update();   # THIS CRASHES

clipMapper = vtkDataSetMapper();
clipMapper.SetInputConnection(clipClosedSurface.GetOutputPort());

boxActor = vtkActor();
boxActor.SetMapper(clipMapper);
boxActor.GetProperty().SetColor(0.8900, 0.8100, 0.3400);

ren = vtkRenderer()
ren.AddActor(boxActor)

win = vtkRenderWindow()
win.AddRenderer(ren)

iren = vtkRenderWindowInteractor()
win.SetInteractor(iren)

iren.Initialize()
iren.Start()

On Mon, May 25, 2015 at 5:18 PM, kent myers via vtkusers <vtkusers at vtk.org>
wrote:

> I am trying to clip a box constructed as a polydata mesh.  I have tried the
> vtkClipPolyData class based on the quadric surface example in the following
> link, but have not succeeded.
>
> http://www.vtk.org/Wiki/VTK/Examples/Cxx/Meshes/SolidClip
>
> I found the vtkClipClosedSurface class and it seems like exactly what I am
> looking for, but I could not find any examples of how to use it.  The code
> below shows my attempt.  It crashes when calling the Update() method.
> Without that call, I get no visible result.
>
> Any help would be appreciated!
>
> Kent
>
>         private static void createBox() {
>                 float[] points = {
>                                 0.0f, 0.0f, 0.0f,
>                                 1.0f, 0.0f, 0.0f,
>                                 1.0f, 1.0f, 0.0f,
>                                 0.0f, 1.0f, 0.0f,
>                                 0.0f, 0.0f, 1.0f,
>                                 1.0f, 0.0f, 1.0f,
>                                 1.0f, 1.0f, 1.0f,
>                                 0.0f, 1.0f, 1.0f,
>                                 };
>                 int[] seq = {
>                                 4, 0, 1, 2, 3,
>                                 4, 1,5,6,2,
>                                 4, 5,4,7,6,
>                                 4, 4,0,3,7,
>                                 4, 0,1,5,4,
>                                 4, 3,2,6,7};
>
>
>                 // create a plane for clipping
>                 vtkPlane plane = new vtkPlane();
>                 plane.SetOrigin(0.0, 0.0, 0.5);
>                 plane.SetNormal(0, 0, 1);
>
>                 // create the box from points and sequence
>                 vtkPolyData polyData = new vtkPolyData();
>                 vtkPoints vtkPoints = new vtkPoints();
>                 vtkFloatArray d = new vtkFloatArray();
>                 d.SetJavaArray(points);
>                 d.SetNumberOfComponents(3);
>                 vtkPoints.SetData(d);
>                 polyData.SetPoints(vtkPoints);
>                 vtkCellArray vtkCells = new vtkCellArray();
>                 vtkIdTypeArray array = new vtkIdTypeArray();
>                 vtkIntArray intArray = new vtkIntArray();
>                 intArray.SetJavaArray(seq);
>                 array.DeepCopy(intArray);
>                 vtkCells.SetCells(seq.length, array);
>                 polyData.SetPolys(vtkCells);
>
>                 vtkClipClosedSurface clipClosedSurface = new
> vtkClipClosedSurface();
>                 vtkPlaneCollection planes = new vtkPlaneCollection();
>                 planes.AddItem(plane);
>                 clipClosedSurface.SetClippingPlanes(planes);
>                 clipClosedSurface.AddInputData(polyData);
>                 clipClosedSurface.Update();   // THIS CRASHES
>
>                 vtkDataSetMapper clipMapper = new vtkDataSetMapper();
>
> clipMapper.SetInputConnection(clipClosedSurface.GetOutputPort());
>
>                 boxActor = new vtkActor();
>                 boxActor.SetMapper(clipMapper);
>                 boxActor.GetProperty().SetColor(0.8900, 0.8100, 0.3400);
>
>         }
>
>
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