gdSPDefLookAt.3p
1.14 KB
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.TH gdSPDefLookAt 3P local "Silicon Graphics, Inc."
.SH NAME
.upperok
gdSPDefLookAt \- load x and y screen space coordinate directions into LookAt
structure.
.SH C SPECIFICATION
.nf
\f3#include "gbi.h"
typedef union {
Light l[2];
} LookAt;
LookAt gdSPDefLookAt(signed char rightx, signed char righty, signed char rightz,
signed char upx, signed char upy, signed char upz)
.fi
\fP
.SH PARAMETERS
.TP 10
.I rightx, righty, rightz
x, y, z components in viewing space of x direction in screen space
.TP
.I upx, upy, upz
x, y, z components in viewing space of y direction in screen space
.TP
.SH DESCRIPTION
The
.I gdSPDefLookAt (3P)
command loads the x and y screen space coordinate directions into a LookAt
structure. The x and y direction unit vectors, whose components are expressed
in the viewing space, must be converted to a signed 8-bit fixed point
representation. Each component c must undergo the conversion:
.PP
.B ((int) MIN(((c) * (128.0)),127.0) & 0xff)
.PP
The LookAt structure serves as input for the
.I gSPLookAt (3P)
command, used in the set up process for specular highlights or reflection
mapping.
.SH SEE ALSO
.IR gSPLookAt (3P)