/VCONE, WN, PHI
Defines the view cone angle for perspective displays.
-
WN Window number (or ALL) to which command applies (defaults to 1).
-
PHI View cone angle (0.0 to 85.°) to define perspective. Use
PHI= 45.0° for typical perspective. Increase angle for more perspective, decrease angle for less. If the distance [/DIST] is not specified, it will be automatically calculated to give full window magnification. If the distance is also specified,PHIcontrols both the perspective and the magnification. The larger the angle, the more the perspective and the less the magnification. Defaults to 0.0 (no perspective).
Notes
Perspective shows the true depth of the object in the display. A variable magnification results since the back plane of the object is further from the observer than the front plane. The largest magnification occurs at the front plane. With perspective, the magnification factor (MAGF) is not only a function of the distance from the object, but also the window shape and the perspective (or view cone) angle Φ as follows:
where
, for square windows, is the
largest in-plane vertical or horizontal dimension, d is the distance from
the observer to the plane of
(usually
the front plane of the object), and Φ is the view cone angle (defined
with the /VCONE command). The bigger the cone angle, the
more the perspective. The magnification factor proportionally decreases with
increasing Φ. The distance can be defined with the /DIST or
the /FOCUS command. Note, the distance input on the /DIST command
is equal to d only if the focus point is located on the plane of
. It is recommended that if a general perspective is desired
(i.e., not any specific cone angle), use Φ = 45.0 (since TAN(45.0) = 1.0)
and let the d value be automatically calculated for full window magnification.
Note that any number of /DIST, /FOCUS, and /VCONE combinations can be used to produce the same magnification. Distances less than the object depth will produce views from within the object.
A magnification factor of 1.0 just fills the window. If the automatic scaling option is used [/AUTO], the magnification factor is fixed at 0.91 (to allow a 10% margin around the object) and d is automatically calculated for the given /VCONE and /FOCUS values. Any value of Φ between 0.0 and 85.0 (usually 45.0) may be used to activate the perspective. Views from inside the object are not possible when d is automatically calculated (use manual scaling [/USER] along with /DIST specification).
This command is valid in any processor.