[vtkusers] vtkBooleanOperationPolyDataFilter including disconnected faces

[Cory Quammen]

Hi Eric,

I am one of the main contributors of the boolean operation filters. I
will take a look at this bug within the next couple days.

Thanks,
Cory

On Mon, Jan 23, 2012 at 12:59 PM, Fahlgren, Eric
<efahlgren at lifemodeler.com> wrote:
> Here's another shot of a similar configuration (I think I've moved the spheres from the previous example).  This one clearly shows the odd shading on the stitching, which look to me to be normals pointed off to Mars or possibly Alpha Centauri.  Could they just be pointed 180 off, an inside/outside detection problem when generating those new faces that glue the surfaces together?
>
> http://www.lifemodeler.com/eric/badNormals.png
>
> Eric
>
>>
>> Two problems, possibly related:
>>
>> 1) When I perform two successive Boolean operations, extraneous faces from
>> the second solid of the final operation are left in the polydata.
>>
>> 2) Note the faces in the red box of the linked image.  The normals appear
>> to be incorrect, there are occasional dark regions in odd places on the
>> resulting polydata.
>>
>> Is there a filter I can add after the Boolean operations to eliminate the
>> extra faces?  How about straightening up the normals?
>>
>> Thanks,
>> Eric
>>
>> #!/usr/bin/env python
>>
>> import vtk
>>
>> LHS = vtk.vtkCubeSource()
>> LHS.SetCenter((0.0, 0.0, 0.8))
>>
>> if 1:
>>    triangle = vtk.vtkTriangleFilter()
>>    triangle.SetInputConnection(LHS.GetOutputPort())
>>    LHS = triangle
>>
>> if 1:
>>    RHS = vtk.vtkSphereSource()
>>    RHS.SetCenter((0.5, 0.0, 0.2))
>>    RHS.SetRadius(1.0); RHS.SetPhiResolution(40);
>> RHS.SetThetaResolution(40)
>>
>>    boolOp = vtk.vtkBooleanOperationPolyDataFilter()
>>    boolOp.SetOperation(vtk.VTK_DIFFERENCE)
>>    boolOp.SetInputConnection(0, LHS.GetOutputPort())
>>    boolOp.SetInputConnection(1, RHS.GetOutputPort())
>>    LHS = boolOp
>>
>> if 1:
>>    RHS = vtk.vtkSphereSource()
>>    RHS.SetCenter((-0.5, 0.0, 0.3))
>>    RHS.SetRadius(1.0); RHS.SetPhiResolution(40);
>> RHS.SetThetaResolution(40)
>>
>>    boolOp = vtk.vtkBooleanOperationPolyDataFilter()
>>    boolOp.SetOperation(vtk.VTK_DIFFERENCE)
>>    boolOp.SetInputConnection(0, LHS.GetOutputPort())
>>    boolOp.SetInputConnection(1, RHS.GetOutputPort())
>>    LHS = boolOp
>>
>> if 0:
>>    fill = vtk.vtkFillHolesFilter()
>>   #fill.SetHoleSize(1.0)
>>    fill.SetInputConnection(LHS.GetOutputPort())
>>    LHS = fill
>>
>> mapper = vtk.vtkPolyDataMapper()
>> mapper.SetInputConnection(LHS.GetOutputPort(0))
>> mapper.ScalarVisibilityOff()
>>
>> actor = vtk.vtkActor()
>> actor.SetMapper(mapper)
>>
>> renderer = vtk.vtkRenderer()
>> renderWindow = vtk.vtkRenderWindow()
>> renderWindow.AddRenderer(renderer)
>> renderWindow.SetSize(1024, 1024)
>>
>> renderer.AddActor(actor)
>>
>> interactor = vtk.vtkRenderWindowInteractor()
>> interactor.SetRenderWindow(renderWindow)
>> interactor.Initialize()
>> renderWindow.Render()
>> interactor.Start()
>
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-- 
Cory Quammen
Research Associate
Department of Computer Science
The University of North Carolina at Chapel Hill