- back clipping plane
- The plane, parallel to the view plane, that specifies
the back of the view volume. Points with a VRC
n-value less than the back clipping plane n-value will be
not be visible in the view window.
Introduction to Computer Graphics,
p204
A parallel projection view volume truncated by the
front and back clipping planes. DOP
is the direction of projection.
Introduction to Computer Graphics,
p204
- back distance (B)
- The signed value that represents the distance of the
back clipping plane from the VRP measured along the
VPN, with positive values in the direction of the VPN.
Introduction to Computer Graphics,
p204
- front clipping plane
- The plane, parallel to the view plane, that specifies
the front of the view volume. Points with a VRC
n-value greater than the front clipping plane n-value will be
not be visible in the view window.
Introduction to Computer Graphics,
p204
A perspective projection view volume truncated by the
front and back clipping planes.
Introduction to Computer Graphics,
p205
- front distance (F)
- The signed value that represents the distance of the
front clipping plane from the VRP measured along the
VPN, with positive values in the direction of the VPN.
Introduction to Computer Graphics,
p204
- projection reference point (PRP)
- The point, specified in VRC system coordinates, where
the view originates. Objects are "seen" by looking through the PRP
toward the center of the view window.
Introduction to Computer Graphics,
p203
A parallel orthographic projection. The direction of projection is
the vector from the PRP to the center of the view window,
and is parallel to the VPN. The shear-parallel matrix
would be equal to the identity matrix in this case.
Introduction to Computer Graphics,
p204
A perspective projection. The direction of projection for any given
point is the vector from the PRP to that point.
Introduction to Computer Graphics,
p202
-
shear-parallel matrix
- The matrix, used in creating the view of an object, that shears
the view volume such that the direction of projection becomes parallel
to the z-axis. It is applied after the view-orientation matrix
and adjusts the view
for a PRP that is not lined up with the view window
center along the VRC n-axis.
Introduction to Computer Graphics,
p218
- view-orientation matrix
- The matrix which transforms points represented in world
coordinates into their VRC equivalent.
It translates the VRP to the origin and then rotates the
VRC so its u, v and n axes align with the
world-coordinate system x, y and z axes, respectively.
Introduction to Computer Graphics,
p205, 218
- view-plane normal (VPN)
- A normal to the view plane. The VPN defines the
VRC n-axis. It is specified in world coordinates.
Introduction to Computer Graphics,
p201
- view reference point (VRP)
- The point in world coordinates which defines the VRC origin.
Introduction to Computer Graphics,
p201
- view-up vector (VUP)
- The vector which determines the VRC v-axis direction.
It is specified in world coordinates.
Introduction to Computer Graphics,
p202
The VRC v-axis is defined by the projection of the
VUP parallel to the VPN onto the view plane.
Introduction to Computer Graphics,
p202
- view volume
- The portion of the world that is projected
onto the view plane. Only objects which are in the
view volume are visible in the view window.
Introduction to Computer Graphics,
p203
- view window
- A window in the view plane bounded by the VRC
(umin, vmin) and
(umax, vmax) points. These points are listed
as VWmin and VWmax in the
View Control Window.
Introduction to Computer Graphics,
p203
The view window as it sits in the view plane. Note: The
view window center does not have to be equal to the VRP.
Introduction to Computer Graphics,
p202
- viewing-reference coordinate (VRC)
system
- The right-handed, (u, v, n) coordinate system that specifies
how the world is viewed. Viewing parameters are defined in
VRC system coordinates.
Introduction to Computer Graphics,
p202
The VRC origin is the VRP. It's n-axis is defined by
the VPN. It's u-axis direction is the vector cross product of
the VUP and VPN. And it's v-axis is the vector cross
product of its z-axis (the VPN) and its x-axis.
Introduction to Computer Graphics,
p202
- world-coordinate (WC) system
- The infinite, right-handed, (x, y, z) coordinate system that is
centered at the origin. A point's WC location is its absolute
position. All other coordinate systems are defined in relationship to
the world-coordinate system.
Introduction to Computer Graphics,
p180, 190