[Visualpython-users] Helix Bugs

[Joel K. <jj...@ya...>]

Jonathan Brandmeyer asked for details on bugs I've
found in the new helix function. Here goes.

When I ran the following code . . .

from visual import *
hlx = helix (pos = (-0.5, 0.0, 0.0), radius = 5.0,
coils = 20.0, thickness = 0.6, color = (0.99, 0.01,
0.9))

. . . I got a tightly wound tall skinny purple helix.
On the other hand, when I ran this . . .

from visual import *
hlx = helix ()
hlx.pos = (-0.5, 0.0, 0.0)
hlx.radius = 5.0
hlx.coils = 20.0
hlx.thickness = 0.6
hlx.color = (0.99, 0.01, 0.9)

. . . I just got a plain loose gray helix. The only
attribute that changed from the basic defaults was the
position. The two programs should, in principle,
produce identical results. The new version of VPython
still seems to do on-the-fly changes to older objects
perfectly well; as far as I can tell, the helix is the
only place where this problem shows up.

In a separate experimental program, I attempted to
apply the "object.rotate" function to the helix, and
got an error message telling me that the helix does
not have the "rotate" attribute. If the helix is
derived from the "curve" object--as it visually
appears to be--then this makes sense, and we might
have to stick with using a frame to rotate a helix. Of
course, the documentation really should contain a
description of the situation, whatever it is.

If it makes any difference, my OS is Windows XP.

Joel



		
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