> Date:         Thu, 6 Jun 2002 04:59:28 -0600
> From: Raul Rios <[EMAIL PROTECTED]>
>
> I'm getting a bit confused when reading
> the Java3D API documentation about the class
> "View"...
>
> What are the differences between the physical and
> the virtual world (or physical and virtual coordinates) ?

For most Java 3D programming you won't need to know much about physical
coordinates.  About the only place it comes up for most people is in the
policies for the front and back clip planes, which unfortunately default to
PHYSICAL_EYE.  If you set these policies to VIRTUAL_EYE you can pretty much
just operate in the virtual world space.

Physical coordinates relate to objects in the physical world such as screens
and the position of the user's eyes.  For most viewing applications the
correspondence between the physical and virtual world does not need to be
exact.  For instance, Java 3D assumes that the pixel density of a screen is 90
pixels/inch to get the physical screen and window sizes for its viewing
computations.

The correspondence is mostly only critical for virtual reality applications,
where an accurate calibration between the display devices and the user position
is needed to create the sense of immersion.  If this is what you're interested
in, then you will need a good understanding of physical coordinates.

If you have more specific questions just let us know.

-- Mark Hood

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