def getCoG(self,
fp,
vol,
roll=Units.parseQuantity("0 deg"),
trim=Units.parseQuantity("0 deg")):
"""Return the fluid volume center of gravity, provided the volume of
fluid inside the tank.
The returned center of gravity is refered to the untransformed ship.
Keyword arguments:
fp -- Part::FeaturePython object affected.
vol -- Volume of fluid.
roll -- Ship roll angle.
trim -- Ship trim angle.
If the fluid volume is bigger than the total tank one, it will be
conveniently clamped.
"""
# Change the units of the volume, and clamp the value
if vol <= 0.0:
return Vector()
if vol >= fp.Shape.Volume:
vol = 0.0
for solid in fp.Shape.Solids:
vol += solid.Volume
sCoG = solid.CenterOfMass
cog.x = cog.x + sCoG.x * solid.Volume
cog.y = cog.y + sCoG.y * solid.Volume
cog.z = cog.z + sCoG.z * solid.Volume
cog.x = cog.x / vol
cog.y = cog.y / vol
cog.z = cog.z / vol
return cog
# Get a first estimation of the level
level = vol.Value / fp.Shape.Volume
# Transform the tank shape
current_placement = fp.Placement
m = current_placement.toMatrix()
m.rotateX(roll.getValueAs("rad"))
m.rotateY(-trim.getValueAs("rad"))
fp.Placement = Placement(m)
# Iterate to find the fluid shape
for i in range(COMMON_BOOLEAN_ITERATIONS):
shape = self.getVolume(fp, level, return_shape=True)
error = (vol.Value - shape.Volume) / fp.Shape.Volume
if abs(error) < 0.01:
break
level += error
# Get the center of gravity
vol = 0.0
cog = Vector()
if len(shape.Solids) > 0:
for solid in shape.Solids:
vol += solid.Volume
sCoG = solid.CenterOfMass
cog.x = cog.x + sCoG.x * solid.Volume
cog.y = cog.y + sCoG.y * solid.Volume
cog.z = cog.z + sCoG.z * solid.Volume
cog.x = cog.x / vol
cog.y = cog.y / vol
cog.z = cog.z / vol
# Untransform the object to retrieve the original position
fp.Placement = current_placement
p = Part.Point(cog)
m = Matrix()
m.rotateY(trim.getValueAs("rad"))
m.rotateX(-roll.getValueAs("rad"))
p.rotate(Placement(m))
return Vector(p.X, p.Y, p.Z)
def displacement(ship,
draft=None,
roll=Units.parseQuantity("0 deg"),
trim=Units.parseQuantity("0 deg")):
"""Compute the ship displacement
Position arguments:
ship -- Ship object (see createShip)
Keyword arguments:
draft -- Ship draft (Design ship draft by default)
roll -- Roll angle (0 degrees by default)
trim -- Trim angle (0 degrees by default)
Returned values:
disp -- The ship displacement (a density of the water of 1025 kg/m^3 is
assumed)
B -- Bouyance application point, i.e. Center of mass of the underwater side
Cb -- Block coefficient
The Bouyance center is referred to the original ship position.
"""
if draft is None:
draft = ship.Draft
shape, base_z = placeShipShape(ship.Shape.copy(), draft, roll, trim)
shape = getUnderwaterSide(shape)
vol = 0.0
cog = Vector()
if len(shape.Solids) > 0:
for solid in shape.Solids:
vol += solid.Volume
sCoG = solid.CenterOfMass
cog.x = cog.x + sCoG.x * solid.Volume
cog.y = cog.y + sCoG.y * solid.Volume
cog.z = cog.z + sCoG.z * solid.Volume
cog.x = cog.x / vol
cog.y = cog.y / vol
cog.z = cog.z / vol
bbox = shape.BoundBox
Vol = (bbox.XMax - bbox.XMin) * (bbox.YMax - bbox.YMin) * abs(bbox.ZMin)
# Undo the transformations on the bouyance point
B = Part.Point(Vector(cog.x, cog.y, cog.z))
m = Matrix()
m.move(Vector(0.0, 0.0, draft))
m.move(Vector(-draft * math.sin(trim.getValueAs("rad")), 0.0, 0.0))
m.rotateY(trim.getValueAs("rad"))
m.move(Vector(0.0, -draft * math.sin(roll.getValueAs("rad")), base_z))
m.rotateX(-roll.getValueAs("rad"))
B.transform(m)
try:
cb = vol / Vol
except ZeroDivisionError:
msg = QtGui.QApplication.translate(
"ship_console",
"ZeroDivisionError: Null volume found during the displacement"
" computation!", None)
App.Console.PrintError(msg + '\n')
cb = 0.0
# Return the computed data
return (DENS * Units.Quantity(vol, Units.Volume), Vector(B.X, B.Y,
B.Z), cb)
def displacement(ship, draft=None,
roll=Units.parseQuantity("0 deg"),
trim=Units.parseQuantity("0 deg")):
"""Compute the ship displacement
Position arguments:
ship -- Ship object (see createShip)
Keyword arguments:
draft -- Ship draft (Design ship draft by default)
roll -- Roll angle (0 degrees by default)
trim -- Trim angle (0 degrees by default)
Returned values:
disp -- The ship displacement (a density of the water of 1025 kg/m^3 is
assumed)
B -- Bouyance application point, i.e. Center of mass of the underwater side
Cb -- Block coefficient
The Bouyance center is refered to the original ship position.
"""
if draft is None:
draft = ship.Draft
shape, base_z = placeShipShape(ship.Shape.copy(), draft, roll, trim)
shape = getUnderwaterSide(shape)
vol = 0.0
cog = Vector()
if len(shape.Solids) > 0:
for solid in shape.Solids:
vol += solid.Volume
sCoG = solid.CenterOfMass
cog.x = cog.x + sCoG.x * solid.Volume
cog.y = cog.y + sCoG.y * solid.Volume
cog.z = cog.z + sCoG.z * solid.Volume
cog.x = cog.x / vol
cog.y = cog.y / vol
cog.z = cog.z / vol
bbox = shape.BoundBox
Vol = (bbox.XMax - bbox.XMin) * (bbox.YMax - bbox.YMin) * abs(bbox.ZMin)
# Undo the transformations on the bouyance point
B = Part.Point(Vector(cog.x, cog.y, cog.z))
m = Matrix()
m.move(Vector(0.0, 0.0, draft))
m.move(Vector(-draft * math.sin(trim.getValueAs("rad")), 0.0, 0.0))
m.rotateY(trim.getValueAs("rad"))
m.move(Vector(0.0,
-draft * math.sin(roll.getValueAs("rad")),
base_z))
m.rotateX(-roll.getValueAs("rad"))
B.transform(m)
try:
cb = vol / Vol
except ZeroDivisionError:
msg = QtGui.QApplication.translate(
"ship_console",
"ZeroDivisionError: Null volume found during the displacement"
" computation!",
None,
QtGui.QApplication.UnicodeUTF8)
App.Console.PrintError(msg + '\n')
cb = 0.0
# Return the computed data
return (DENS * Units.Quantity(vol, Units.Volume),
Vector(B.X, B.Y, B.Z),
cb)
def getCoG(self, fp, vol, roll=Units.parseQuantity("0 deg"),
trim=Units.parseQuantity("0 deg")):
"""Return the fluid volume center of gravity, provided the volume of
fluid inside the tank.
The returned center of gravity is referred to the untransformed ship.
Keyword arguments:
fp -- Part::FeaturePython object affected.
vol -- Volume of fluid.
roll -- Ship roll angle.
trim -- Ship trim angle.
If the fluid volume is bigger than the total tank one, it will be
conveniently clamped.
"""
# Change the units of the volume, and clamp the value
if vol <= 0.0:
return Vector()
if vol >= fp.Shape.Volume:
vol = 0.0
for solid in fp.Shape.Solids:
vol += solid.Volume
sCoG = solid.CenterOfMass
cog.x = cog.x + sCoG.x * solid.Volume
cog.y = cog.y + sCoG.y * solid.Volume
cog.z = cog.z + sCoG.z * solid.Volume
cog.x = cog.x / vol
cog.y = cog.y / vol
cog.z = cog.z / vol
return cog
# Get a first estimation of the level
level = vol.Value / fp.Shape.Volume
# Transform the tank shape
current_placement = fp.Placement
m = current_placement.toMatrix()
m.rotateX(roll.getValueAs("rad"))
m.rotateY(-trim.getValueAs("rad"))
fp.Placement = Placement(m)
# Iterate to find the fluid shape
for i in range(COMMON_BOOLEAN_ITERATIONS):
shape = self.getVolume(fp, level, return_shape=True)
error = (vol.Value - shape.Volume) / fp.Shape.Volume
if abs(error) < 0.01:
break
level += error
# Get the center of gravity
vol = 0.0
cog = Vector()
if len(shape.Solids) > 0:
for solid in shape.Solids:
vol += solid.Volume
sCoG = solid.CenterOfMass
cog.x = cog.x + sCoG.x * solid.Volume
cog.y = cog.y + sCoG.y * solid.Volume
cog.z = cog.z + sCoG.z * solid.Volume
cog.x = cog.x / vol
cog.y = cog.y / vol
cog.z = cog.z / vol
# Untransform the object to retrieve the original position
fp.Placement = current_placement
p = Part.Point(cog)
m = Matrix()
m.rotateY(trim.getValueAs("rad"))
m.rotateX(-roll.getValueAs("rad"))
p.rotate(Placement(m))
return Vector(p.X, p.Y, p.Z)
