class ShapeProps(object):
"""
Base class for shape properties.
"""
def __init__(self):
self._props = GProp_GProps()
@property
def mass(self):
"""
:return: The mass of the shape. This corresponds to total length for
linear properties, total area for surface properties, or total
volume for volume properties.
:rtype: float
"""
return self._props.Mass()
@property
def cg(self):
"""
:return: The center of gravity.
:rtype: afem.geometry.entities.Point
"""
gp_pnt = self._props.CentreOfMass()
return Point(gp_pnt.X(), gp_pnt.Y(), gp_pnt.Z())
@property
def static_moments(self):
"""
:return: The static moments of inertia Ix, Iy, and Iz.
:rtype: tuple(float)
"""
return self._props.StaticMoments(0., 0., 0.)
@property
def matrix_of_inertia(self):
"""
:return: The 3 x 3 matrix of inertia.
:rtype: numpy.ndarray
"""
gp_mat = self._props.MatrixOfInertia()
matrix = []
for j in range(1, 4):
row = []
for i in range(1, 4):
row.append(gp_mat.Value(i, j))
matrix.append(row)
return array(matrix, dtype=float)
def moment_of_inertia(self, axis):
"""
Compute the moment of inertia about the axis.
:param afem.geometry.entities.Axis1 axis: The axis.
:return: The moment of inertia.
:rtype: float
"""
return self._props.MomentOfInertia(axis)
def volume(self):
"""
:return: The voume of all solids of the shape.
:rtype: float
"""
props = GProp_GProps()
BRepGProp.VolumeProperties_(self.object, props, True)
return props.Mass()
def area(self):
"""
:return: The area of all faces of the shape.
:rtype: float
"""
props = GProp_GProps()
BRepGProp.SurfaceProperties_(self.object, props, True)
return props.Mass()
def length(self):
"""
:return: The length of all edges of the shape.
:rtype: float
"""
props = GProp_GProps()
BRepGProp.LinearProperties_(self.object, props, True)
return props.Mass()
def shape_faces_surface():
""" Compute the surface of each face of a shape
"""
# first create the shape
the_shape = BRepPrimAPI_MakeBox(50., 30., 10.).Shape()
# then loop over faces
t = TopologyExplorer(the_shape)
props = GProp_GProps()
shp_idx = 1
for face in t.faces():
brepgprop_SurfaceProperties(face, props)
face_surf = props.Mass()
print("Surface for face nbr %i : %f" % (shp_idx, face_surf))
shp_idx += 1
def cube_inertia_properties():
""" Compute the inertia properties of a shape
"""
# Create and display cube
print("Creating a cubic box shape (50*50*50)")
cube_shape = BRepPrimAPI_MakeBox(50., 50., 50.).Shape()
# Compute inertia properties
props = GProp_GProps()
brepgprop_VolumeProperties(cube_shape, props)
# Get inertia properties
mass = props.Mass()
cog = props.CentreOfMass()
matrix_of_inertia = props.MatrixOfInertia()
# Display inertia properties
print("Cube mass = %s" % mass)
cog_x, cog_y, cog_z = cog.Coord()
print("Center of mass: x = %f;y = %f;z = %f;" % (cog_x, cog_y, cog_z))
print("Matrix of inertia", matrix_of_inertia)
class PropsBase(object):
"""
Base class for shape properties.
"""
def __init__(self):
self._props = GProp_GProps()
@property
def mass(self):
"""
:return: The mass of the shape. This corresponds to total length for
linear properties, total area for surface properties, or total
volume for volume properties.
:rtype: float
"""
return self._props.Mass()
@property
def cg(self):
"""
:return: The center of gravity.
:rtype: OCCT.gp.gp_Pnt
"""
return self._props.CentreOfMass()
@property
def static_moments(self):
"""
:return: The static moments of inertia Ix, Iy, and Iz.
:rtype: tuple(float)
"""
return self._props.StaticMoments(0., 0., 0.)
def moment_of_inertia(self, axis):
"""
Compute the moment of inertia about the axis.
:param OCCT.gp.gp_Ax1 axis: The axis.
:return: The moment of inertia.
:rtype: float
"""
return self._props.MomentOfInertia(axis)
def system(self):
self._system = GProp_GProps()
# todo, type should be abstracted with TopoDS...
_topo_type = self.instance.topo_type
if _topo_type == 'face' or _topo_type == 'shell':
brepgprop_SurfaceProperties(self.instance, self._system)
elif _topo_type == 'edge':
brepgprop_LinearProperties(self.instance, self._system)
elif _topo_type == 'solid':
brepgprop_VolumeProperties(self.instance, self._system)
return self._system
def on_select(shapes):
"""
Parameters
----------
shape : TopoDS_Shape
"""
g1 = GProp_GProps()
for shape in shapes:
brepgprop_LinearProperties(shape, g1)
mass = g1.Mass()
centre_of_mass = g1.CentreOfMass()
com_x = centre_of_mass.X()
com_y = centre_of_mass.Y()
com_z = centre_of_mass.Z()
static_moments = g1.StaticMoments()
print("shape {shape}: \n mass: {mass}"
"\n center of mass: {com_x}, {com_y}, {com_z}"
"\n static moments: {static_moments}".format(**vars()))
def _build_solid(compound, divide_closed):
"""
Method to try and build a valid solid from an OpenVSP component.
"""
# Get all the faces in the compound. The surfaces must be split. Discard
# any with zero area.
top_exp = TopExp_Explorer(compound, TopAbs_FACE)
faces = []
while top_exp.More():
shape = top_exp.Current()
face = CheckShape.to_face(shape)
fprop = GProp_GProps()
BRepGProp.SurfaceProperties_(face, fprop, 1.0e-7)
a = fprop.Mass()
if a <= 1.0e-7:
top_exp.Next()
continue
faces.append(face)
top_exp.Next()
# Replace any planar B-Spline surfaces with planes
non_planar_faces = []
planar_faces = []
for f in faces:
hsrf = BRep_Tool.Surface_(f)
try:
is_pln = GeomLib_IsPlanarSurface(hsrf, 1.0e-7)
if is_pln.IsPlanar():
w = ShapeAnalysis.OuterWire_(f)
# Fix the wire because they are usually degenerate edges in
# the planar end caps.
builder = BRepBuilderAPI_MakeWire()
for e in ExploreShape.get_edges(w):
if LinearProps(e).length > 1.0e-7:
builder.Add(e)
w = builder.Wire()
fix = ShapeFix_Wire()
fix.Load(w)
geom_pln = Geom_Plane(is_pln.Plan())
fix.SetSurface(geom_pln)
fix.FixReorder()
fix.FixConnected()
fix.FixEdgeCurves()
fix.FixDegenerated()
w = fix.WireAPIMake()
# Build the planar face
fnew = BRepBuilderAPI_MakeFace(w, True).Face()
planar_faces.append(fnew)
else:
non_planar_faces.append(f)
except RuntimeError:
non_planar_faces.append(f)
# Make a compound of the faces
shape = CreateShape.compound(non_planar_faces + planar_faces)
# Split closed faces
if divide_closed:
divide = ShapeUpgrade_ShapeDivideClosed(shape)
divide.Perform()
shape = divide.Result()
# Sew shape
sew = BRepBuilderAPI_Sewing(1.0e-7)
sew.Load(shape)
sew.Perform()
sewn_shape = sew.SewedShape()
if sewn_shape.ShapeType() == TopAbs_FACE:
face = sewn_shape
sewn_shape = TopoDS_Shell()
builder = BRep_Builder()
builder.MakeShell(sewn_shape)
builder.Add(sewn_shape, face)
# Attempt to unify planar domains
unify_shp = ShapeUpgrade_UnifySameDomain(sewn_shape, False, True, False)
unify_shp.Build()
shape = unify_shp.Shape()
# Make solid
shell = ExploreShape.get_shells(shape)[0]
solid = ShapeFix_Solid().SolidFromShell(shell)
# Limit tolerance
FixShape.limit_tolerance(solid)
# Check shape validity
check_shp = BRepCheck_Analyzer(solid, True)
if check_shp.IsValid():
return solid, True, []
else:
invalid_shapes = _topods_iterator_check(solid, check_shp)
return solid, False, invalid_shapes
def __init__(self):
self._props = GProp_GProps()
def linear(self):
'''returns the length of a wire or edge
'''
prop = GProp_GProps()
brepgprop_LinearProperties(self.shape, prop)
return prop
def surface(self):
'''returns the area of a surface
'''
prop = GProp_GProps()
brepgprop_SurfaceProperties(self.shape, prop, self.tolerance)
return prop
def volume(self):
'''returns the volume of a solid
'''
prop = GProp_GProps()
brepgprop_VolumeProperties(self.shape, prop, self.tolerance)
return prop
def length(self):
props = GProp_GProps()
BRepGProp.LinearProperties_(self.shape, props, True)
return props.Mass() # Don't ask
