def get_preferred_direction(self,beam):
# Obtain the moment vector
u1,u2,u3 = beam.global_default_axes()
m11,m22,m33 = self.get_moment_magnitudes(beam.name)
# Quick debugging - making sure the torsion doesn't get too high
if not helpers.compare(m11,0,4):
#pdb.set_trace()
pass
# Sum m22 and m33 (m11 is torsion, which doesn't play a role in the direction)
moment_vector = helpers.sum_vectors(helpers.scale(m22,u2),helpers.scale(m33,u3))
'''
Cross axis-1 with the moment vector to obtain the positive clockwise direction
This keeps the overall magnitude of moment_vector since u1 is a unit vector
We are always attempting to repair further up the broken beam (closer to
the j-end). The cross will always give us the vector in the right direction
if we do it this way.
'''
twist_direction = helpers.cross(moment_vector,u1)
# Project the twist direction onto the xy-plane and normalize to have a
# maximum of 45 degree approach (or, as specified in the variables.py)
# depending on the ratio of moment magnitude to max_magnitude
xy_change = (twist_direction[0],twist_direction[1],0)
# The rotation is parallel to the z-axis, so we don't add disturbance
if helpers.compare(helpers.length(xy_change),0):
# Return the normal direction - which way is the beam leaning???
return super(MomentAwareBuilder,self).get_preferred_direction(beam)
# We know the direction in which the beam is turning
else:
# Get direction of travel (this is a unit vector)
travel = super(MomentAwareBuilder,self).get_preferred_direction(beam)
# Normalize twist to the maximum moment of force -- structure_check
normal = helpers.normalize(xy_change,construction.beam['structure_check'])
# The beam is vertical - check to see how large the normalized moment is
if travel is None:
# The change is relatively small, so ignore it
if helpers.length(normal) <= helpers.ratio(construction.beam['verticality_angle']):
return travel
else:
return helpers.make_unit(normal)
else:
scalar = 1 / helpers.ratio(construction.beam['moment_angle_max'])
scaled_travel = helpers.scale(scalar,travel)
return helpesr.make_unit(helpers.sum_vectors(normal,scaled_travel))
def global_default_axes(self):
'''
Returns the default local axes. Later on we might incorporate the ability to return
rotated axes.
'''
axis_1 = helpers.make_unit(helpers.make_vector(self.endpoints.i,
self.endpoints.j))
vertical = (math.sin(math.radians(helpers.smallest_angle(axis_1,(0,0,1))))
<= 0.001)
# Break up axis_1 into unit component vectors on 1-2 plane, along with
# their maginitudes
u1, u2 = (axis_1[0],axis_1[1],0),(0,0,axis_1[2])
l1,l2 = helpers.length(u1), helpers.length(u2)
u1 = helpers.make_unit(u1) if not helpers.compare(l1,0) else (1,1,0)
u2 = helpers.make_unit(u2) if not helpers.compare(l2,0) else (0,0,1)
# Calculate axis_2 by negating and flipping componenet vectors of axis_1
axis_2 = (1,0,0) if vertical else helpers.make_unit(helpers.sum_vectors(
helpers.scale(-1 * l2,u1),helpers.scale(l1,u2)))
# Make it have a positive z-component
axis_2 = axis_2 if axis_2[2] > 0 else helpers.scale(-1,axis_2)
# Calculate axis_3 by crossing axis 1 with axis 2 (according to right hand
# rule)
axis_3 = helpers.cross(axis_1,axis_2)
axis_3 = helpers.make_unit((axis_3[0],axis_3[1],0)) if vertical else axis_3
# Sanity checks
# Unit length
assert helpers.compare(helpers.length(axis_3),1)
# On the x-y plane
assert helpers.compare(axis_3[2],0)
return axis_1,axis_2,axis_3
