vtkBooleanOperationPolyDataFilter not working correctly
The difference is not correct. Here is an example.
import vtk
def create_tetrahedron(): points = vtk.vtkPoints() points.InsertNextPoint(2, 0.5, 0.5) # Point 0 points.InsertNextPoint(-0.5, -0.5, 0.5) # Point 1 points.InsertNextPoint(-0.5, 0.5, -0.5) # Point 2 points.InsertNextPoint(0.5, -0.5, -0.5) # Point 3
triangles = vtk.vtkCellArray()
# Correcting the order for outward normals
triangle_indices = [
(0, 2, 1), # Face opposite vertex 3
(0, 1, 3), # Face opposite vertex 2
(0, 3, 2), # Face opposite vertex 1
(1, 2, 3) # Face opposite vertex 0
]
for idx in triangle_indices:
triangle = vtk.vtkTriangle()
triangle.GetPointIds().SetId(0, idx[0])
triangle.GetPointIds().SetId(1, idx[1])
triangle.GetPointIds().SetId(2, idx[2])
triangles.InsertNextCell(triangle)
polydata = vtk.vtkPolyData()
polydata.SetPoints(points)
polydata.SetPolys(triangles)
return polydata
def create_box(): # Define points for the box points = vtk.vtkPoints() points.InsertNextPoint(-1, -1, -1) points.InsertNextPoint(1, -1, -1) points.InsertNextPoint(1, 1, -1) points.InsertNextPoint(-1, 1, -1) points.InsertNextPoint(-1, -1, 1) points.InsertNextPoint(1, -1, 1) points.InsertNextPoint(1, 1, 1) points.InsertNextPoint(-1, 1, 1)
# Create the triangles for each face of the box
triangles = vtk.vtkCellArray()
# Helper function to create two triangles for each face
def add_face(indices):
triangle1 = vtk.vtkTriangle()
triangle2 = vtk.vtkTriangle()
triangle1.GetPointIds().SetId(0, indices[0])
triangle1.GetPointIds().SetId(1, indices[1])
triangle1.GetPointIds().SetId(2, indices[2])
triangle2.GetPointIds().SetId(0, indices[2])
triangle2.GetPointIds().SetId(1, indices[3])
triangle2.GetPointIds().SetId(2, indices[0])
triangles.InsertNextCell(triangle1)
triangles.InsertNextCell(triangle2)
# Define each face with correct winding to ensure outward normals
add_face([0, 3, 2, 1]) # Bottom
add_face([4, 5, 6, 7]) # Top
add_face([0, 1, 5, 4]) # Front
add_face([2, 3, 7, 6]) # Back
add_face([0, 4, 7, 3]) # Left
add_face([1, 2, 6, 5]) # Right
# Create a polydata object
polydata = vtk.vtkPolyData()
polydata.SetPoints(points)
polydata.SetPolys(triangles)
return polydata
def subtract_meshes(mesh1, mesh2): boolean_filter = vtk.vtkBooleanOperationPolyDataFilter() boolean_filter.SetOperationToDifference() boolean_filter.SetInputData(0, mesh1) boolean_filter.SetInputData(1, mesh2) boolean_filter.Update() return boolean_filter.GetOutput()
def main(): tetrahedron = create_tetrahedron() box = create_box()
result_mesh = subtract_meshes(box, tetrahedron)
mapper = vtk.vtkPolyDataMapper()
mapper.SetInputData(result_mesh)
actor = vtk.vtkActor()
actor.SetMapper(mapper)
renderer = vtk.vtkRenderer()
renderer.AddActor(actor)
renderer.SetBackground(0.1, 0.2, 0.3)
renderWindow = vtk.vtkRenderWindow()
renderWindow.AddRenderer(renderer)
renderWindow.SetSize(300, 300)
renderWindowInteractor = vtk.vtkRenderWindowInteractor()
renderWindowInteractor.SetRenderWindow(renderWindow)
# add wireframe of box to the renderWindow
wireframeMapper = vtk.vtkPolyDataMapper()
wireframeMapper.SetInputData(tetrahedron)
wireframeActor = vtk.vtkActor()
wireframeActor.SetMapper(wireframeMapper)
wireframeActor.GetProperty().SetRepresentationToWireframe()
renderer.AddActor(wireframeActor)
renderWindow.Render()
renderWindowInteractor.Start()
if name == "main": main()