perspe(3G)perspe(3G)NAMEperspe - defines a perspective projection transformation
FORTRAN SPECIFICATION
subroutine perspe(fovy, aspect, near, far)
integer*4 fovy
real aspect, near, far
PARAMETERS
fovy expects the field-of-view angle in the y direction. The field
of view is the range of the area that is being viewed. fovy
must be > 2 or an error results.
aspect expects the aspect ratio which determines the field of view in
the x direction. The aspect ratio is the ratio of x (width) to
y (height).
near expects the distance from the viewer to the closest clipping
plane (always positive).
far expects the distance from the viewer to the farthest clipping
plane (always positive).
DESCRIPTIONperspe specifies a viewing pyramid into the world coordinate system. In
general, the aspect ratio in perspe should match the aspect ratio of the
associated viewport. For example, aspect=2.0 means the viewer's angle of
view is twice as wide in x as it is in y. If the viewport is twice as
wide as it is tall, it displays the image without distortion.
When the system is in single matrix mode, perspe loads a matrix onto the
transformation stack, replacing the current top matrix. When the system
is in viewing, projection, or texture matrix mode, perspe replaces the
current Projection matrix and leaves the ModelView matrix stack and the
Texture matrix unchanged.
SEE ALSO
mmode, ortho, viewpo, window
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