import pygimli as pg
[docs]
def streamline(mesh, field, startCoord, dLengthSteps, dataMesh=None,
maxSteps=1000, verbose=False, coords=(0, 1)):
"""Create a streamline from start coordinate and following a vector field in up and down direction.
"""
xd, yd, vd = streamlineDir(mesh, field, startCoord, dLengthSteps,
dataMesh=dataMesh, maxSteps=maxSteps,
down=True, verbose=verbose, coords=coords)
c = mesh.findCell(startCoord)
if c is not None:
c.setValid(True)
xu, yu, vu = streamlineDir(mesh, field, startCoord, dLengthSteps,
dataMesh=dataMesh, maxSteps=maxSteps,
down=False, verbose=verbose, coords=coords)
return xd + xu[1:], yd + yu[1:], vd + vu[1:]
[docs]
def streamlineDir(mesh, field, startCoord, dLengthSteps, dataMesh=None,
maxSteps=150, down=True, verbose=False, coords=(0, 1)):
"""
down = -1, up = 1, both = 0
"""
xd = []
yd = []
vd = []
pot = None
vx = None
vy = None
isVectorData = False
if isinstance(field, pg.PosVector):
field = field.array()
if hasattr(field[0], '__len__'):
if abs(max(field[:, 0])) == 0 and abs(max(field[:, 1]) == 0):
raise Exception("No data range streamline: min/max == ",
min(field[:, 0]))
vx = pg.Vector(field[:, 0])
vy = pg.Vector(field[:, 1])
isVectorData = True
else:
if min(field) == max(field):
raise Exception("No scalar data range for any gradients "
" to draw a streamline: min/max == ",
min(field))
if dataMesh is not None:
if len(field) == dataMesh.nodeCount():
pot = pg.Vector(field)
elif len(field) == dataMesh.cellCount():
pot = pg.core.cellDataToPointData(dataMesh, field)
else:
print(len(field), dataMesh)
raise Exception("Data length (%i) for streamline is "
"neighter nodeCount (%i) nor cellCount (%i)" %
(len(field), dataMesh.nodeCount(), dataMesh.nodeCount()))
else:
if len(field) == mesh.nodeCount():
pot = pg.Vector(field)
elif len(field) == mesh.cellCount():
pot = pg.core.cellDataToPointData(mesh, field)
else:
print(len(field), dataMesh)
raise Exception("Data length (%i) for streamline is "
"neighter nodeCount (%i) nor cellCount (%i)" %
(len(field), mesh.nodeCount(), mesh.nodeCount()))
direction = 1
if down:
direction = -1
# search downward
pos = pg.RVector3(startCoord)
c = mesh.findCell(startCoord)
dLength = c.center().dist(c.node(0).pos()) / dLengthSteps
# stream line starting point
if c is not None:
xd.append(pos[coords[0]])
yd.append(pos[coords[1]])
vd.append(-1)
lastC = c
lastU = -direction * 1e99
d = None
while c is not None and len(xd) < maxSteps:
# valid .. temporary check if there is already a stream within the cell
if not c.valid():
break
if isVectorData:
u = 0.
if len(vx) == mesh.cellCount():
d = pg.RVector3(vx[c.id()], vy[c.id()])
elif len(vx) == mesh.nodeCount():
d = pg.RVector3(c.pot(pos, vx), c.pot(pos, vy))
elif dataMesh:
cd = dataMesh.findCell(pos)
if cd is None:
raise Exception("Cannot find " + str(pos) + " dataMesh")
if len(vx) == dataMesh.cellCount():
d = pg.RVector3(vx[cd.id()], vy[cd.id()])
elif len(vx) == dataMesh.nodeCount() and \
len(vy) == dataMesh.nodeCount():
d = pg.RVector3(cd.pot(pos, vx), cd.pot(pos, vy))
else:
print(dataMesh, len(vx), len(vy))
raise Exception("data size wrong")
else:
print("mesh:", mesh, len(vx), len(vy))
raise Exception("Data length neighter node size or cell size.")
else:
if dataMesh:
cd = dataMesh.findCell(pos)
if not cd:
break
d = cd.grad(pos, pot)
u = cd.pot(pos, pot)
else:
d = c.grad(pos, pot)
u = c.pot(pos, pot)
# always go u down
dAbs = d.length()
#print("cell:", c.id(), u, d, dAbs)
if dAbs == 0.0:
#print(d, "check this in streamlineDir(",)
break
if down:
if u > lastU:
break
else:
if u < lastU:
break
# * min(1.0, ((startCoord - pos).length()))
pos += direction * d / dAbs * dLength
c = mesh.findCell(pos, False)
# Change cell here .. set old cell to be processed
if c is not None:
xd.append(pos[coords[0]])
yd.append(pos[coords[1]])
# set the stating value here
if vd[0] == -1:
vd[0] = dAbs
vd.append(dAbs)
## check for degenerating stream
if len(xd) > 2:
pos0 = pg.Pos(xd[-3], yd[-3])
pos1 = pg.Pos(xd[-2], yd[-2])
pos2 = pg.Pos(xd[-1], yd[-1])
if (pos0.dist(pos2) < pos0.dist(pos1)):
pg.debug('degenerating stream aborted')
break
# If the new cell is different from the current we move into the
# new cell and make the last to be invalid ..
# the last active contains a stream element
if c.id() != lastC.id():
lastC.setValid(False)
lastC = c
dLength = c.center().dist(c.node(0).pos()) / dLengthSteps
else:
# There is no new cell .. the last active contains a stream element
lastC.setValid(False)
lastU = u
if verbose:
print(pos, u)
# Stream line has stopped and the current cell (if there is one) ..
# .. contains a stream element
if c is not None:
c.setValid(False)
if down:
xd.reverse(), yd.reverse(), vd.reverse()
return xd, yd, vd
