[Visualpython-users] Strange curve behavior

[Matthew K. <mko...@ma...>]

I know that "curve" has a history of behaving strangely when too many 
points get appended, but I've encountered a weird behavior I don't think 
I've seen before.

A trail is being appended that tracks a moving object.  After a short 
time, the trail stops appending, and a straight line segment is drawn 
from the last appended point to the current position of the moving 
object.  This continues for a while, then the curve is suddenly updated 
to include all previously undrawn points, and the weird "connecting line 
segment" behavior starts again.

This is hard to describe in words, so I've posted a movie of it.  The 
movie file is 1.3 MB and is in Windows Media format.  Download the file at:

http://www4.ncsu.edu/~makohlmy/curve_bug.wmv

The code that generated this output is attached.  Note the behavior 
starts after about 1000 iterations. (In this program, deltat is one day, 
loop stops after 6 years, behavior starts about halfway in, or 
3*365=1095 iterations.)  So I don't think this is a case of too many 
locations appended.  I've certainly seen past student programs that have 
much larger trails than this that display perfectly.

System specs:
Windows XP SP2
AMD Athlon 64 3200+, 2.0 GHz, 1.0 GB RAM
Video:  GeForce 6200 TurboCache, PCI Express x16, 256 MB
ForceWare version: 81.98

Video drivers are up to date.  Turning off hardware acceleration does 
not fix the problem.

Any ideas? (Apologies if this has already been reported.)


Thanks,

Matt Kohlmyer
School of Physics
Georgia Institute of Technology