[Visualpython-users] funny effects using opacity

[Guy K. K. <g....@ma...>]

Hi,

I have just tried to visualise a series of 288 measurement points in 3D using 
vpython. All works quite nicely. As I'm using now the standard deviations of 
each point in X, Y and Z direction for the size of the boxes I'm using to 
render each point I had difficulties to see all points properly as they 
overlapped. The solution was to set the (thanks for that) new feature to set 
an opacity on the objects to 0.2.

Now unfortunately when rotating the scene I see that certain faces of the 
cubes/boxes seem to be flickering on and off for the individual measurement 
points. That's in a way quite annoying, especially as I'm assuming that not 
all faces of the boxes then are rendered. Another assumption is, that 
rendering polyhedrons the hidden faces are not rendered. But using opacity 
there then are no truly hidden faces, and the scene looks quite different 
with/without them.

Any ideas on how that could be fixed? I assume it needs fixing in vpython 
itself, though. Or is it a "feature" of the OpenGL implementation on my 
machine (Nvidia chipset on a Linux box, Ubuntu Jaunty)?

Guy

-- 
Guy K. Kloss
Institute of Information and Mathematical Sciences
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