[Visualpython-users] frame() (bug or feature?)

[<rsa...@mt...>]

On Windows XP SP3 (Python 2.5.1, VPython 3.2.11), the following use of 
frame() gives an unexpected flip in the y- and z-axes in some of the 
frames.

By uncommenting the line:
if costh<0: Fup=-Fup
I get the desired behavior.

Is this a bug?

Rob Salgado


# example of frame()

from visual import *

scene.background=(.5,.5,.5)
scene.forward=(0,20,-10)

DEG=math.pi/180.
F=[]

for th in arange(0,360*DEG, 30*DEG):
   costh=cos(th)
   sinth=sin(th)

   Fup=scene.up
   #if costh<0:    Fup=-Fup

   F.append(frame(pos=6*norm( vector(costh, sinth, 0) ), 
axis=vector(costh,sinth,0) , up=Fup))

   arrow(frame=F[-1],color=color.red,   axis=vector(1,0,0) )
   arrow(frame=F[-1],color=color.green, axis=vector(0,1,0) )
   arrow(frame=F[-1],color=color.blue,  axis=vector(0,0,1) )
   label(frame=F[-1],text="%3d" % round(th/DEG) ,box=0, opacity=0)



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