def cdtFromPSLG(pslg, onlyInner = False):
"""cdtFromPSLG(pslg, onlyInner) -> GeoMap
Return a CDT for the given planar straight line graph. `pslg`
should be a GeoMap whose node positions are simple input points
and edges define constraint segments.
FIXME: ATM, this function may crash if the input contains
duplicate points (e.g. within the same edge). This is due to a
limitation of the triangle module, i.e. J. Shewchuck's code.
"""
# return constrainedDelaunayMap(
# list(pslg.edgeIter()), pslg.imageSize(),
# [node.position() for node in pslg.nodeIter() if node.isIsolated()],
# onlyInner = False)
points = []
segments = []
holes = []
nodes = [None] * pslg.maxNodeLabel()
for node in pslg.nodeIter():
nodes[node.label()] = len(points)
points.append(node.position())
for edge in pslg.edgeIter():
l = len(points)
edgeSegments = [(l+i-1, l+i) for i in range(len(edge)-1)]
edgeSegments[0] = (nodes[edge.startNodeLabel()], edgeSegments[0][1])
edgeSegments[-1] = (edgeSegments[-1][0], nodes[edge.endNodeLabel()])
points.extend(edge[1:-1])
# for i in range(1, len(edge)-1):
# assert edge[i] not in points, "%s[%d] = ..%s,%s,%s,.. is already present!" % (
# edge, i, edge[i-1], edge[i], edge[i+1])
# points.append(edge[i])
segments.extend(edgeSegments)
for face in pslg.faceIter(skipInfinite = True):
if face.flag(OUTER_FACE):
# FIXME: re-use available scanlines for face:
holes.append(_pointInHole(contourPoly(face.contour())))
print "- performing Constrained Delaunay Triangulation..."
print " (%d points, %s segments, %d holes)" % (
len(points), len(segments), len(holes))
nodePositions, edgeData = triangle.constrainedDelaunay(
points, segments, onlyInner, holes)
print "- storing result in a GeoMap..."
result = _delaunayMapFromData(nodePositions, edgeData, pslg.imageSize())
for edge in result.edgeIter():
if edgeData[edge.label()][2]:
edge.setFlag(CONTOUR_SEGMENT)
result.face(0).setFlag(OUTER_FACE)
for holePoint in holes:
result.faceAt(holePoint).setFlag(OUTER_FACE)
return result
def cdtFromPSLG(pslg, onlyInner = False):
"""cdtFromPSLG(pslg, onlyInner) -> GeoMap
Return a CDT for the given planar straight line graph. `pslg`
should be a GeoMap whose node positions are simple input points
and edges define constraint segments.
FIXME: ATM, this function may crash if the input contains
duplicate points (e.g. within the same edge). This is due to a
limitation of the triangle module, i.e. J. Shewchuck's code.
"""
# return constrainedDelaunayMap(
# list(pslg.edgeIter()), pslg.imageSize(),
# [node.position() for node in pslg.nodeIter() if node.isIsolated()],
# onlyInner = False)
points = []
segments = []
holes = []
nodes = [None] * pslg.maxNodeLabel()
for node in pslg.nodeIter():
nodes[node.label()] = len(points)
points.append(node.position())
for edge in pslg.edgeIter():
l = len(points)
edgeSegments = [(l+i-1, l+i) for i in range(len(edge)-1)]
edgeSegments[0] = (nodes[edge.startNodeLabel()], edgeSegments[0][1])
edgeSegments[-1] = (edgeSegments[-1][0], nodes[edge.endNodeLabel()])
points.extend(edge[1:-1])
# for i in range(1, len(edge)-1):
# assert edge[i] not in points, "%s[%d] = ..%s,%s,%s,.. is already present!" % (
# edge, i, edge[i-1], edge[i], edge[i+1])
# points.append(edge[i])
segments.extend(edgeSegments)
for face in pslg.faceIter(skipInfinite = True):
if face.flag(OUTER_FACE):
# FIXME: re-use available scanlines for face:
holes.append(_pointInHole(contourPoly(face.contour())))
print "- performing Constrained Delaunay Triangulation..."
print " (%d points, %s segments, %d holes)" % (
len(points), len(segments), len(holes))
nodePositions, edgeData = triangle.constrainedDelaunay(
points, segments, onlyInner, holes)
print "- storing result in a GeoMap..."
result = _delaunayMapFromData(nodePositions, edgeData, pslg.imageSize())
for edge in result.edgeIter():
if edgeData[edge.label()][2]:
edge.setFlag(CONTOUR_SEGMENT)
result.face(0).setFlag(OUTER_FACE)
for holePoint in holes:
result.faceAt(holePoint).setFlag(OUTER_FACE)
return result
def constrainedDelaunayMap(polygons, imageSize, extraPoints = [],
onlyInner = True):
"""constrainedDelaunayMap(polygons, imageSize, extraPoints, onlyInner) -> GeoMap
Returns a new `GeoMap` containing a Constrained Delaunay
Triangulation of all points of the polygons plus the extraPoints
if given. The segments of the polygons will be constrained
segments of the CDT.
If the optional `onlyInner` parameter is True (default), then all
edge segments in the 'outside' will be removed. (This assumes
that all closed polygons with a negative partialArea() are
holes.)
**NOTE**: You probably want to use `cdtFromPSLG` or `faceCDTMap`
instead, both of which have a much simpler API."""
assert triangle, """For correct CDT, you need to compile the
triangle module (vigra/experiments/triangle). You might want to
try the home-made fakedConstrainedDelaunayMap instead, which will
give a correct result if possible, but may just throw an exception
if it has to give up or even go into an infinite loop."""
points = list(extraPoints)
segments = []
holes = []
for polygon in polygons:
l = len(points)
partPoints = list(polygon)
partSegments = [(l+i, l+i+1) for i in range(len(partPoints)-1)]
if polygon[-1] == polygon[0]:
del partPoints[-1]
if partPoints[0] in points:
for i, (s, e) in enumerate(partSegments):
partSegments[i] = (s-1, e-1) # partPoints[0] will be deleted
partSegments[0] = (points.index(partPoints[0]), partSegments[0][1])
del partPoints[0]
partSegments[-1] = (partSegments[-1][0], partSegments[0][0])
if onlyInner and polygon.partialArea() < 0:
holes.append(_pointInHole(polygon))
else:
if partPoints[-1] in points:
partSegments[-1] = (partSegments[-1][0], points.index(partPoints[-1]))
del partPoints[-1]
if partPoints[0] in points:
for i, (s, e) in enumerate(partSegments):
partSegments[i] = (s-1, e-1) # partPoints[0] will be deleted
partSegments[0] = (points.index(partPoints[0]), partSegments[0][1])
del partPoints[0]
points.extend(partPoints)
segments.extend(partSegments)
print "- performing Constrained Delaunay Triangulation..."
print " (%d points, %s segments, %d holes)" % (
len(points), len(segments), len(holes))
nodePositions, edgeData = triangle.constrainedDelaunay(
points, segments, onlyInner, holes)
print "- storing result in a GeoMap..."
result = _delaunayMapFromData(nodePositions, edgeData, imageSize)
for edge in result.edgeIter():
if edgeData[edge.label()][2]:
edge.setFlag(CONTOUR_SEGMENT)
result.face(0).setFlag(OUTER_FACE)
for holePoint in holes:
result.faceAt(holePoint).setFlag(OUTER_FACE)
return result
def constrainedDelaunayMap(polygons, imageSize, extraPoints = [],
onlyInner = True):
"""constrainedDelaunayMap(polygons, imageSize, extraPoints, onlyInner) -> GeoMap
Returns a new `GeoMap` containing a Constrained Delaunay
Triangulation of all points of the polygons plus the extraPoints
if given. The segments of the polygons will be constrained
segments of the CDT.
If the optional `onlyInner` parameter is True (default), then all
edge segments in the 'outside' will be removed. (This assumes
that all closed polygons with a negative partialArea() are
holes.)
**NOTE**: You probably want to use `cdtFromPSLG` or `faceCDTMap`
instead, both of which have a much simpler API."""
assert triangle, """For correct CDT, you need to compile the
triangle module (vigra/experiments/triangle). You might want to
try the home-made fakedConstrainedDelaunayMap instead, which will
give a correct result if possible, but may just throw an exception
if it has to give up or even go into an infinite loop."""
points = list(extraPoints)
segments = []
holes = []
for polygon in polygons:
l = len(points)
partPoints = list(polygon)
partSegments = [(l+i, l+i+1) for i in range(len(partPoints)-1)]
if polygon[-1] == polygon[0]:
del partPoints[-1]
if partPoints[0] in points:
for i, (s, e) in enumerate(partSegments):
partSegments[i] = (s-1, e-1) # partPoints[0] will be deleted
partSegments[0] = (points.index(partPoints[0]), partSegments[0][1])
del partPoints[0]
partSegments[-1] = (partSegments[-1][0], partSegments[0][0])
if onlyInner and polygon.partialArea() < 0:
holes.append(_pointInHole(polygon))
else:
if partPoints[-1] in points:
partSegments[-1] = (partSegments[-1][0], points.index(partPoints[-1]))
del partPoints[-1]
if partPoints[0] in points:
for i, (s, e) in enumerate(partSegments):
partSegments[i] = (s-1, e-1) # partPoints[0] will be deleted
partSegments[0] = (points.index(partPoints[0]), partSegments[0][1])
del partPoints[0]
points.extend(partPoints)
segments.extend(partSegments)
print "- performing Constrained Delaunay Triangulation..."
print " (%d points, %s segments, %d holes)" % (
len(points), len(segments), len(holes))
nodePositions, edgeData = triangle.constrainedDelaunay(
points, segments, onlyInner, holes)
print "- storing result in a GeoMap..."
result = _delaunayMapFromData(nodePositions, edgeData, imageSize)
for edge in result.edgeIter():
if edgeData[edge.label()][2]:
edge.setFlag(CONTOUR_SEGMENT)
result.face(0).setFlag(OUTER_FACE)
for holePoint in holes:
result.faceAt(holePoint).setFlag(OUTER_FACE)
return result
