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import vtk
from vtk.test import Testing
from vtk.util.misc import vtkGetDataRoot
VTK_DATA_ROOT = vtkGetDataRoot()
# This script tests vtkBandedPolyDataContourFilter (BPDCF)
# Create 8 renderers, each showing a 4-point polydata with
# a different combinations of (poly)vertices, (poly)lines,
# triangles, quads, with a positive or negative range of scalars,
# and with cells that are oriented counter-clockwise or clockwise.
legend="""
Legend of the 8 renderers:
1 3 5 7
2 4 6 8
cell orientation, fill-cell, scalars, scalar-mode
--------------------------------------------------------
1. counter-clockwise, 1 quad, positive, index
2. clockwise, 2 triangles, positive, index
3. counter-clockwise, 1 quad, negative, index
4. clockwise, 1 strip, negative, index
5. counter-clockwise, 1 quad, positive, value
6. clockwise, 2 triangles, positive, value
7. counter-clockwise, 1 quad, negative, value
8. clockwise, 1 strip, negative, value
"""
def InsertCell(cellArray,points,orientation):
"""
Insert the cell counter-clockwise (orientation == True)
or clockwise (orientation == False)
"""
cellArray.InsertNextCell(len(points))
if orientation:
for p in points:
cellArray.InsertCellPoint(p)
else:
for p in reversed(points):
cellArray.InsertCellPoint(p)
def generatePolyData(orientation,fillWith,factor):
"""
Generate poly-data and point-scalars
"""
poly = vtk.vtkPolyData()
pts = vtk.vtkPoints()
coords=[ (0,0,0),(1,0,0),(1,1,0),(0,1,0)]
for coord in coords:
pts.InsertNextPoint(coord[0],coord[1],coord[2])
poly.SetPoints(pts)
# Vertices at all corners
# two 1-point vertices and 1 2-point poly-vertex
vertices = [[0],[1],[2,3]]
verts = vtk.vtkCellArray()
for vertex in vertices:
InsertCell(verts,vertex,orientation)
poly.SetVerts(verts)
# Lines at all sides of the quad
# two 2-point lines and 1 3-point line
edges = [ (0,1),(1,2),(2,3,0) ]
lines = vtk.vtkCellArray()
for edge in edges:
InsertCell(lines,edge,orientation)
poly.SetLines(lines)
# Fill with one quad, two triangles or a triangle-strip
if fillWith=='quad':
quad = (0,1,2,3)
polys = vtk.vtkCellArray()
InsertCell(polys,quad,orientation)
poly.SetPolys(polys)
elif fillWith=='triangles':
triangles=[(0,1,3),(3,1,2)]
strips = vtk.vtkCellArray()
for triangle in triangles:
InsertCell(strips,triangle,orientation)
poly.SetStrips(strips)
elif fillWith=='strip':
strip=(0,1,3,2)
strips = vtk.vtkCellArray()
InsertCell(strips,strip,orientation)
poly.SetStrips(strips)
# Scalars for contouring
values = [ 0.0, 0.5, 1.5, 1.0 ]
array=vtk.vtkDoubleArray()
for v in values:
array.InsertNextValue(factor*v)
poly.GetPointData().SetScalars(array)
return poly
def contourCase(poly,mode):
"""
Create a renderer, actor, mapper to contour the polydata
poly : polydata to contour
mode : scalar-mode for BPDCF
"""
# Prepare an array of point-data scalars
# Perform the contouring. Note that we need to set scalar
# mode to index because line cells do not get contour values
# even if scalar mode is set to value.
valueRange=poly.GetPointData().GetScalars().GetRange()
num=5
bpdcf = vtk.vtkBandedPolyDataContourFilter()
bpdcf.SetInputData(poly)
bpdcf.GenerateValues( num, valueRange[0],valueRange[1] )
bpdcf.GenerateContourEdgesOff()
if mode == 'index':
bpdcf.SetScalarModeToIndex()
elif mode == 'value':
bpdcf.SetScalarModeToValue()
bpdcf.Update()
# Shrink all cells somewhat so the contouring of edges can
# be seen better
sf = vtk.vtkShrinkFilter()
sf.SetShrinkFactor(0.90)
sf.SetInputConnection( bpdcf.GetOutputPort())
# Mapper shows contour index values
m = vtk.vtkDataSetMapper()
m.SetInputConnection(sf.GetOutputPort())
m.SetScalarModeToUseCellData()
m.SetScalarRange(bpdcf.GetOutput().GetCellData().GetArray('Scalars').GetRange())
a = vtk.vtkActor()
a.SetMapper(m)
return a
# four contouring cases to test
cases = [ (True, 'quad', 100.0, [0.0,0.5,0.5,1.0]), # 1,5 : upper-left
(False, 'triangles', 100.0, [0.0,0.0,0.5,0.5]), # 2,6 : lower-left
(True, 'quad', -100.0, [0.5,0.5,1.0,1.0]), # 3,7 : upper-right
(False, 'strip', -100.0, [0.5,0.0,1.0,0.5]), ] # 4,8 : lower-right
# Two sets of four renderers, left four yielding index-numbers, right four
# yielding contour-values
v0=0
dv=.5
renWin = vtk.vtkRenderWindow()
for mode in ['index','value']:
for (orient,fill,factor,vp1) in cases:
vp2 = [ v0 + vp1[0]*dv, vp1[1], v0 + vp1[2]*dv, vp1[3] ]
poly=generatePolyData(orient,fill,factor)
actor = contourCase(poly,mode)
ren = vtk.vtkRenderer()
ren.AddViewProp( actor )
ren.SetViewport( vp2 )
renWin.AddRenderer( ren )
v0 += dv
print(legend)
renWin.SetSize(400,200)
iren = vtk.vtkRenderWindowInteractor()
iren.SetRenderWindow(renWin)
renWin.Render()
iren.Initialize()
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