.\" @(#)PEXViewOrientationMatrix.3 1.4 95/03/24 SMI;
.so man3/pex.macs
.TH PEXViewOrientationMatrix 3 "May 1995" "Solaris PEXlib Reference Manual" ""
.SH NAME
PEXViewOrientationMatrix - utility function
.SH SYNTAX
.HP
int PEXViewOrientationMatrix\^(\^PEXCoord *\fIvrp\fP, PEXVector *\fIvpn\fP, PEXVector *\fIvup\fP, PEXMatrix \fImatrix_return\fP\^)
.SH PARAMETERS
.IP \fIvrp\fP 1i
View reference point.
.IP \fIvpn\fP 1i
View plane normal.
.IP \fIvup\fP 1i
View up vector.
.IP \fImatrix_return\fP 1i
Matrix into which result is stored.
.SH RETURNS
.LP
Zero if successful; otherwise, one of the following:
.TP
.B PEXBadVector
Either
.I vpn
or
.I vup
is zero length.
.TP
.B PEXBadVectors
.I vup
is parallel to
.I vpn.
.SH DESCRIPTION
.\" indexing
.IX PEXViewOrientationMatrix
.LP
This function creates a view orientation matrix that
transforms world coordinates (WC) to view reference
coordinates (VRC).  This matrix is used in conjunction with a view
mapping matrix as the viewing matrices for a designated view.
.LP
The view reference point (VRP) defines the point in world
coordinate space that is to be used as the origin of the
view reference coordinate system.
.LP
The view plane normal (VPN) is a 3D vector defined in world
coordinates relative to the view reference point.  This
gives the direction of the positive Z axis of VRC.
.LP
The view up vector (VUP) is a 3D vector defined in
world coordinates relative to the view reference point.
The projection of this vector onto the plane through
the view reference point and perpendicular to the
view plane normal defines the Y axis of VRC.
.LP
The X axis of VRC is defined such that the VRC system
forms a right-handed coordinate system.
.SH ERRORS
.LP
None
.SH SEE ALSO
.LP
.nf
.BR PEXViewOrientationMatrix2D (3)
.BR PEXViewMappingMatrix (3)
.BR PEXViewMappingMatrix2D (3)
.fi