"Peter J. Holzer" <hjp### [at] SiKituwsracat> wrote in message
news:slr### [at] tealhhjpat...
|
| While playing around with superellipsoids and the orthographic camera I
| found that the superellipsoid vanishes if the camera is pointing exactly
| along the X axis. Here is a short scene file to demonstrate the effect:
|
| If you replace one of the 0.000000 values in the camera location by
| 0.000001 the superellipsoid miraculously appears again.
|
| The povray statistics say:
|
| Ray->Shape Intersection          Tests       Succeeded  Percentage
| ----------------------------------------------------------------------------
| Superellipsoid                   77361               0      0.00
| ----------------------------------------------------------------------------
|
| So it looks like the ray->shape Intersection test for superellipsoids
| doesn't work if the ray is exactly parallel to the x axis.
|
| With a non-orthographic camera this probably doesn't matter since it
| affects at most one ray.

Really makes me wonder what's going on behind the scenes (heh, a pun) anyway.
If the slight offset of x or z from 0 is done and 'orthographic' is placed
first ahead of anything else then the superellipsoid more than fills the
display window.  When placed after 'location' and before 'angle' it shows up
but only as a tiny size.
This behaviour of course has been observed before concerning orthographic
cameras.
However the s.e. is still non-existant it seems otherwise.
Also, unless the axes are offset a fair amount, say <90,1,1> there are
artifacts showing up at the shadow/light boundary, perspective camera or not.

| PS: I hope it is okay to include short scene files directly in the text
| instead of posting them to povray.text.scene-files.

I don't see that as wrong, like you said it is a short description of the
effect.

Bob

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