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# This example demonstrates the use of vtkDepthSortPolyData. This is a
# poor man's algorithm to sort polygons for proper transparent blending.
# It sorts polygons based on a single point (i.e., centroid) so the sorting
# may not work for overlapping or intersection polygons.
#
package require vtk
package require vtkinteraction
# Create a bunch of spheres that overlap and cannot be easily arranged
# so that the blending works without sorting. They are appended into a
# single vtkPolyData because the filter only sorts within a single
# vtkPolyData input.
#
vtkSphereSource sphere
sphere SetThetaResolution 80
sphere SetPhiResolution 40
sphere SetRadius 1
sphere SetCenter 0 0 0
vtkSphereSource sphere2
sphere2 SetThetaResolution 80
sphere2 SetPhiResolution 40
sphere2 SetRadius 0.5
sphere2 SetCenter 1 0 0
vtkSphereSource sphere3
sphere3 SetThetaResolution 80
sphere3 SetPhiResolution 40
sphere3 SetRadius 0.5
sphere3 SetCenter -1 0 0
vtkSphereSource sphere4
sphere4 SetThetaResolution 80
sphere4 SetPhiResolution 40
sphere4 SetRadius 0.5
sphere4 SetCenter 0 1 0
vtkSphereSource sphere5
sphere5 SetThetaResolution 80
sphere5 SetPhiResolution 40
sphere5 SetRadius 0.5
sphere5 SetCenter 0 -1 0
vtkAppendPolyData appendData
appendData AddInputConnection [sphere GetOutputPort]
appendData AddInputConnection [sphere2 GetOutputPort]
appendData AddInputConnection [sphere3 GetOutputPort]
appendData AddInputConnection [sphere4 GetOutputPort]
appendData AddInputConnection [sphere5 GetOutputPort]
# The dephSort object is set up to generate scalars representing
# the sort depth. A camera is assigned for the sorting. The camera
# define the sort vector (position and focal point).
vtkCamera camera
vtkDepthSortPolyData depthSort
depthSort SetInputConnection [appendData GetOutputPort]
depthSort SetDirectionToBackToFront
depthSort SetVector 1 1 1
depthSort SetCamera camera
depthSort SortScalarsOn
depthSort Update
vtkPolyDataMapper mapper
mapper SetInputConnection [depthSort GetOutputPort]
mapper SetScalarRange 0 [[depthSort GetOutput] GetNumberOfCells]
vtkActor actor
actor SetMapper mapper
[actor GetProperty] SetOpacity 0.5
[actor GetProperty] SetColor 1 0 0
actor RotateX -72
# If an Prop3D is supplied, then its transformation matrix is taken
# into account during sorting.
depthSort SetProp3D actor
# Create the RenderWindow, Renderer and both Actors
#
vtkRenderer ren1
ren1 SetActiveCamera camera
vtkRenderWindow renWin
renWin AddRenderer ren1
vtkRenderWindowInteractor iren
iren SetRenderWindow renWin
# Add the actors to the renderer, set the background and size
#
ren1 AddActor actor
ren1 SetBackground 1 1 1
renWin SetSize 300 200
# render the image
#
iren AddObserver UserEvent {wm deiconify .vtkInteract}
ren1 ResetCamera
[ren1 GetActiveCamera] Zoom 2.2
renWin Render
# prevent the tk window from showing up then start the event loop
wm withdraw .
iren Start
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