glLightModelf, glLightModeli,	glLightModelfv,	glLightModeliv
- set	the lighting model parameters

glLightModel
	glLightModelfv(pname, params) -> None
glLightModelf
	glLightModelf(pname, param) -> None
glLightModelfv
	glLightModelfv(pname, params) -> None
glLightModeli
	glLightModeli(pname, param) -> None
glLightModeliv
	glLightModeliv(pname, params) -> None

void glLightModelf( GLenum pname,
                    GLfloat param )
void glLightModeli( GLenum pname,
                    GLint param )

pname	  Specifies a single-valued lighting model parameter.
        GL_LIGHT_MODEL_LOCAL_VIEWER and
        GL_LIGHT_MODEL_TWO_SIDE are accepted.

param	  Specifies the	value that param will be set to.

void glLightModelfv( GLenum pname,
                     const GLfloat *params )
void glLightModeliv( GLenum pname,
                     const GLint *params )

pname
     Specifies a lighting model parameter.
     GL_LIGHT_MODEL_AMBIENT, GL_LIGHT_MODEL_LOCAL_VIEWER,
     and GL_LIGHT_MODEL_TWO_SIDE are accepted.

params
     Specifies a pointer to the value	or values that params
     will be set to.

glLightModel sets the	lighting model parameter.  pname names
a parameter and params gives the new value.  There are three
lighting model parameters:

GL_LIGHT_MODEL_AMBIENT
          params contains four integer or floating-point
          values that	specify	the ambient RGBA intensity of
          the	entire scene.  Integer values are mapped
          linearly such that the most	positive representable
          value maps to 1.0, and the most negative
          representable value	maps to	-1.0.  Floating-point
          values are mapped directly.	 Neither integer nor
          floating-point values are clamped.	The initial
          ambient scene intensity is (0.2, 0.2, 0.2, 1.0).

GL_LIGHT_MODEL_LOCAL_VIEWER
          params is a	single integer or floating-point value
          that specifies how specular	reflection angles are
          computed.  If params is 0 (or 0.0),	specular
          reflection angles take the view direction to be
          parallel to	and in the direction of	the -z axis,
          regardless of the location of the vertex in	eye
          coordinates.  Otherwise, specular reflections are
          computed from the origin of	the eye	coordinate
          system.  The initial value is 0.

GL_LIGHT_MODEL_TWO_SIDE
          params is a	single integer or floating-point value
          that specifies whether one-	or two-sided lighting
          calculations are done for polygons.	 It has	no
          effect on the lighting calculations	for points,
          lines, or bitmaps.	If params is 0 (or 0.0), one-
          sided lighting is specified, and only the front
          material parameters	are used in the	lighting
          equation.  Otherwise, two-sided lighting is
          specified.	In this	case, vertices of back-facing
          polygons are lighted using the back	material
          parameters,	and have their normals reversed	before
          the	lighting equation is evaluated.	 Vertices of
          front-facing polygons are always lighted using the
          front material parameters, with no change to their
          normals. The initial value is 0.

In RGBA mode,	the lighted color of a vertex is the sum of
the material emission	intensity, the product of the material
ambient reflectance and the lighting model full-scene
ambient intensity, and the contribution of each enabled
light	source.	 Each light source contributes the sum of
three	terms:	ambient, diffuse, and specular.	 The ambient
light	source contribution is the product of the material
ambient reflectance and the light's ambient intensity.  The
diffuse light	source contribution is the product of the
material diffuse reflectance,	the light's diffuse intensity,
and the dot product of the vertex's normal with the
normalized vector from the vertex to the light source.  The
specular light source	contribution is	the product of the
material specular reflectance, the light's specular
intensity, and the dot product of the	normalized vertex-to-
eye and vertex-to-light vectors, raised to the power of the
shininess of the material.  All three	light source
contributions	are attenuated equally based on	the distance
from the vertex to the light source and on light source
direction, spread exponent, and spread cutoff	angle.	All
dot products are replaced with 0 if they evaluate to a
negative value.

The alpha component of the resulting lighted color is	set to
the alpha value of the material diffuse reflectance.

In color index mode, the value of the	lighted	index of a
vertex ranges	from the ambient to the	specular values	passed
to glMaterial	using GL_COLOR_INDEXES.	 Diffuse and specular
coefficients,	computed with a	(.30, .59, .11)	weighting of
the lights' colors, the shininess of the material, and the
same reflection and attenuation equations as in the RGBA
case,	determine how much above ambient the resulting index
is.

GL_INVALID_ENUM is generated if pname	is not an accepted
value.

GL_INVALID_OPERATION is generated if glLightModel is
executed between the execution of glBegin and	the
corresponding	execution of glEnd.

glGet	with argument GL_LIGHT_MODEL_AMBIENT
glGet	with argument GL_LIGHT_MODEL_LOCAL_VIEWER
glGet	with argument GL_LIGHT_MODEL_TWO_SIDE
glIsEnabled with argument GL_LIGHTING

glLight, glMaterial