Picking with pfChannel->makeOrtho active

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Dwight Meglan (dwight++at++ht.com)
Tue, 30 Jan 1996 11:31:16 -0400

We have managed to figure out that we cannot pick with pfChannel->pick if
pfChannel->makeOrtho has been used. Our guess is that when ortho is active
the pick ray produced from the mouse position in the pfChannel->pick call
is something rather ill defined, maybe eminating from the center of the
screen. There is mention that the field of view is 0.0 when makeOrtho is
used, so we are guessing that picking needs to have the FOV set to
something non-zero to work properly.

Our current workaround is to set the field of view quite small to make a
telephoto view and adjust our viewpoint so that the view fills the screen.
This gives a good approximation of an ortho view-- our GUI, which is also
in the same scenegraph as the simulation, has a tiny bit of perspective but
not enough to really be bothersome.

We have things working now, but I just want to confirm that we are thinking
about this correctly.

Thanks,
--dwight

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Dwight Meglan, PhD | Developers of complete surgery simulation
Engineering Coordinator | training systems and surgery simulation
High Techsplanations, Inc. | creation software tools
6001 Montrose Rd., Suite 902 |
Rockville, MD 20852-4874 | "Witty, yet erudite saying goes here..."
301 984 3706 x38 |
301 984 2104 : FAX |
dwight++at++ht.com | http://www.ht.com

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