package require vtk

# Simple example that used to crash when an UpdateExtent request
# from one algorithm is overwritten by a smaller UpdateExtent
# request from another algorithm.  The COMBINED_UPDATE_EXTENT
# key was added to vtkStreamingDemandDrivenPipeline to fix the
# bug that caused the crash.

# read an image that has an extent of 0 255 0 255 0 0
vtkPNGReader reader
reader SetDataSpacing 0.8 0.8 1.5
reader SetFileName "$VTK_DATA_ROOT/Data/fullhead15.png"

# Uncomment this to make the crash disappear
#reader Update

# clip the image down to 0 127 0 127 0 0
vtkImageClip clip
clip SetInputConnection [reader GetOutputPort]
clip SetOutputWholeExtent 0 127 0 127 0 0

# darken the background
vtkImageShiftScale darken
darken SetInputConnection [reader GetOutputPort]
darken SetScale 0.2

# do an operation on the clipped and unclipped data
vtkImageBlend blend
blend SetInputConnection [darken GetOutputPort]
blend AddInputConnection [clip GetOutputPort]

vtkImageViewer viewer
viewer SetInputConnection [blend GetOutputPort]
viewer SetColorWindow 2000
viewer SetColorLevel 1000
viewer Render