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# This example demonstrates how to use a programmable filter and how to use
# the special vtkDataSetToDataSet::GetOutputPort() methods
# first we load in the standard vtk packages into tcl
package require vtk
package require vtkinteraction
package require vtktesting
#
# We create a 100 by 100 point plane to sample
#
vtkPlaneSource plane
plane SetXResolution 100
plane SetYResolution 100
#
# We transform the plane by a factor of 10 on X and Y
#
vtkTransform transform
transform Scale 10 10 1
vtkTransformPolyDataFilter transF
transF SetInputConnection [plane GetOutputPort]
transF SetTransform transform
#
# Compute Bessel function and derivatives. We'll use a programmable filter
# for this. Note the unusual GetPolyDataInput() & GetOutputPort() methods.
#
vtkProgrammableFilter besselF
besselF SetInputConnection [transF GetOutputPort]
besselF SetExecuteMethod bessel
#
# The SetExecuteMethod takes a Tcl proc as an argument
# In here is where all the processing is done.
#
proc bessel {} {
set input [besselF GetPolyDataInput]
set numPts [$input GetNumberOfPoints]
vtkPoints newPts
vtkFloatArray derivs
for {set i 0} {$i < $numPts} {incr i} {
set x [$input GetPoint $i]
set x0 [lindex $x 0]
set x1 [lindex $x 1]
set r [expr sqrt($x0*$x0 + $x1*$x1)]
set x2 [expr exp(-$r) * cos(10.0*$r)]
set deriv [expr -exp(-$r) * (cos(10.0*$r) + 10.0*sin(10.0*$r))]
newPts InsertPoint $i $x0 $x1 $x2
eval derivs InsertValue $i $deriv
}
[besselF GetPolyDataOutput] CopyStructure $input
[besselF GetPolyDataOutput] SetPoints newPts
[[besselF GetPolyDataOutput] GetPointData] SetScalars derivs
newPts Delete; #reference counting - it's ok
derivs Delete
}
#
# We warp the plane based on the scalar values calculated above
#
vtkWarpScalar warp
warp SetInputConnection [besselF GetOutputPort]
warp XYPlaneOn
warp SetScaleFactor 0.5
#
# We create a mapper and actor as usual. In the case we adjust the
# scalar range of the mapper to match that of the computed scalars
#
vtkPolyDataMapper mapper
mapper SetInputConnection [warp GetOutputPort]
eval mapper SetScalarRange [[besselF GetPolyDataOutput] GetScalarRange]
vtkActor carpet
carpet SetMapper mapper
#
# Create the RenderWindow, Renderer
#
vtkRenderer ren1
vtkRenderWindow renWin
renWin AddRenderer ren1
vtkRenderWindowInteractor iren
iren SetRenderWindow renWin
ren1 AddActor carpet
renWin SetSize 500 500
# render the image
#
iren AddObserver UserEvent {wm deiconify .vtkInteract}
ren1 ResetCamera
[ren1 GetActiveCamera] Zoom 1.5
renWin Render
# prevent the tk window from showing up then start the event loop
wm withdraw .
iren Start
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