This was a tough one.
There are some 1.2 million questions on python on stackoverflow.
If you search for
[python]"object has no attribute"
you get some 12066 results. So that's probably why this question didn'get much attention.
I tried out the issue with a smaller example according to https://www.glowscript.org/docs/VPythonDocs/compound.html
from vpython import *
handle = cylinder( size=vec(1,.2,.2),color=vec(0.72,0.42,0) )
head = box( size=vec(.2,.6,.2), pos=vec(1.1,0,0),color=color.gray(.6) )
hammer = compound([handle, head])
hammer.axis = vec(1,1,0)
world_pos = hammer.compound_to_world(hammer.axis)
giving the error mentioned in the question:
compound event return
Traceback (most recent call last):
File "hammer.py", line 10, in <module>
print (hammer.origin)
File "/opt/local/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/vpython/vpython.py", line 1536, in origin
return self._origin
AttributeError: 'compound' object has no attribute '_origin'
The relevant source code lines of vpython.py are:
@property
def origin(self):
return self._origin
@origin.setter
def origin(self,value): # compound origin cannot be reset
if not self._constructing:
raise AttributeError('The compound "origin" attribute is read-only; change "pos" instead.')
self._origin = value
def world_to_compound(self, v):
v = v-self._pos
x_axis = self._axis.hat
y_axis = self._up.hat
z_axis = x_axis.cross(y_axis)
ox = self._size0.x/self._size.x # _size0 is the original size
oy = self._size0.y/self._size.y
oz = self._size0.z/self._size.z
return self._origin + vector(v.dot(x_axis)*ox, v.dot(y_axis)*oy, v.dot(z_axis)*oz)
def compound_to_world(self, v):
v = v-self._origin
x_axis = self._axis.hat
y_axis = self._up.hat
z_axis = x_axis.cross(y_axis)
ox = self._size.x/self._size0.x # _size0 is the original size
oy = self._size.y/self._size0.y
oz = self._size.z/self._size0.z
return self._pos + v.x*ox*x_axis + v.y*oy*y_axis + v.z*oz*z_axis
and indeed a few lines further up the constructor does not set any origin.
So adding a default origin:
class compound(standardAttributes):
compound_idx = 0 # same numbering scheme as in GlowScript
def __init__(self, objList, **args):
self._origin = vector(0,0,0)
makes the syntax error go away.
from vpython import *
handle = cylinder( size=vec(1,.2,.2), color=vec(0.72,0.42,0) )
head = box( size=vec(.2,.6,.2), pos=vec(1.1,0,0), color=color.gray(.6) )
hammer = compound([handle, head])
hammer.axis = vec(1,1,0)
print (hammer.origin)
world_pos = hammer.compound_to_world(hammer.axis)
print (world_pos)
then gives the result:
compound event return
<0, 0, 0>
<0.6, 1.41421, 0>
and the eyeballs.py code works as expected:
I do not know there to report this bug but I posted a message to the vpython-users group
