pfBox and pfSphere

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Steve Baker (steve++at++mred.bgm.link.com)
Mon, 8 Jul 96 11:30:24 -0500

Is there an 'official' way to distinguish an empty pfBox or pfSphere?

The man pages don't indicate the existance of a pfIsEmptyBox or
pfIsEmptySPhere - but they hint that there is a 'special' representation
for empty boxes and spheres.

By experiment I see that empty Spheres have a center at (0,0,0) and a radius
of -1.0, and pfBox'es have really large numbers for 'min' and really large
negative numbers for 'max'.

What's not clear is exactly which of these criteria are 'safe' tests for emptyness.

(eg if I test for a sphere of radius != -1.0, will I get into trouble if I scale
the sphere with pfOrthoXformSphere and end up with a radius of -2.0. Is it OK
to test for a negative radius?)

Maybe these tests should be added to Performer in a future release.

Thanks...

   Steve

  Steve Baker 817-323-1361 (Vox-Lab)
  Hughes Training Inc. 817-695-8776 (Vox-Office/vMail)
  2200 Arlington Downs Road 817-695-4028 (Fax)
  Arlington, Texas. TX 76005-6171 steve++at++mred.bgm.link.com (eMail)

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