'\"
'\" Copyright (c) 1997 Maorong Zou
'\" 
.TH EZ_DefineLightModel 3 "" EZWGL "EZWGL Functions"
.BS
.SH NAME
EZ_DefineLightModel, EZ_BindLightModel \- define a lighting model

.SH SYNOPSIS
.nf
.B #include <EZ.h>
.sp
.BI "EZ_LightModel *EZ_DefineLightModel(float *" parameters )
.BI "void EZ_BindLightModel(EZ_LightModel *" lmodel )

.SH ARGUMENTS
.sp
\fIparameters\fR  Specifies material properties.
.sp
\fIlmodel\fR Specifies a pre-defined lighting model.
.sp

.SH DESCRIPTION
.PP
\fBEZ_DefineLightModel\fR defines a lighting model based on the
specified parameters. The defined lighting model can later be
bind the current lighting model.
.PP
\fIparameters\fR specifies an array of floating point symbols and
values that defines the lighting model properties.
\fIparameters\fR must contain a sequence of lighting symbols,
each followed by the appropriate number of floating point values. 
The last symbol must be EZ_NULL_F, which is itself not followed by any
values.
.sp
The symbols are:
.in +3
.sp
\fBEZ_LIGHT_MODEL_AMBIENT_F\fR specifies the ambient color of the
lighting model, Must followed by 4 floats in the range [0.0, 1.0] that specify the
intensity of the RGBA components of the ambient color.
.sp
\fBEZ_LIGHT_MODEL_LOCAL_VIEWER_F\fR specifies whether reflection
calculations are done based on a local or infinitely distant viewpoint.
It must be followed by a single floating point value, which must be
either 0.0 or 1.0.
.sp
\fBEZ_LIGHT_MODEL_TWO_SIDE_F\fR specifies whether lighting
calculations are done assuming that only frontfacing polygons are
visible, or are corrected for each polygon based on whether it is
frontfacing or backfacing. It must be followed by a single floating
point value, which must be either 0.0 or 1.0. The value 1.0 specifies
a lighting model that is correct for both frontfacing and backfacing
polygons. In this case, vertex normals are reversed 
for all vertices of backfacing polygons and the back-material is
used to color backfacing polygons.
.in -3
.PP
\fBEZ_BindLightModel\fR binds the specified pre-defined lighting model
to the current lighting model.

.SH "SEE ALSO"
EZ_DefineLightSrc(3), EZ_DefineMaterial(3), EZ_BindLightSrc(3),
EZ_BindMaterial(3)