GLMATERIAL(3G)															    GLMATERIAL(3G)

NAME

       glMaterialf, glMateriali, glMaterialfv, glMaterialiv - specify material parameters for the lighting model

C SPECIFICATION

       void glMaterialf( GLenum face,
			 GLenum pname,
			 GLfloat param )
       void glMateriali( GLenum face,
			 GLenum pname,
			 GLint param )

PARAMETERS

       face    Specifies which face or faces are being updated.  Must be one of GL_FRONT, GL_BACK, or GL_FRONT_AND_BACK.

       pname   Specifies the single-valued material parameter of the face or faces that is being updated.  Must be GL_SHININESS.

       param   Specifies the value that parameter GL_SHININESS will be set to.

C SPECIFICATION

       void glMaterialfv( GLenum face,
			  GLenum pname,
			  const GLfloat *params )
       void glMaterialiv( GLenum face,
			  GLenum pname,
			  const GLint *params )

PARAMETERS

       face   Specifies which face or faces are being updated.	Must be one of GL_FRONT, GL_BACK, or GL_FRONT_AND_BACK.

       pname  Specifies  the  material	parameter of the face or faces that is being updated.  Must be one of GL_AMBIENT, GL_DIFFUSE, GL_SPECULAR,
	      GL_EMISSION, GL_SHININESS, GL_AMBIENT_AND_DIFFUSE,  or GL_COLOR_INDEXES.

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

DESCRIPTION

       glMaterial assigns values to material parameters.  There are two matched sets of material parameters.  One, the front-facing set,  is  used
       to  shade  points,  lines,  bitmaps,  and all polygons (when two-sided lighting is disabled), or just front-facing polygons (when two-sided
       lighting is enabled).  The other set, back-facing, is used to shade back-facing polygons only when two-sided lighting is enabled.  Refer to
       the glLightModel reference page for details concerning one- and two-sided lighting calculations.

       glMaterial  takes  three  arguments.   The  first,  face,  specifies  whether  the  GL_FRONT  materials,  the  GL_BACK  materials,  or both
       GL_FRONT_AND_BACK materials will be modified.  The second, pname, specifies which of several parameters in one or both sets will  be  modi-
       fied.  The third, params, specifies what value or values will be assigned to the specified parameter.

       Material  parameters  are  used	in  the  lighting  equation  that  is optionally applied to each vertex.  The equation is discussed in the
       glLightModel reference page.  The parameters that can be specified using glMaterial, and their interpretations by  the  lighting  equation,
       are as follows:

       GL_AMBIENT	   params contains four integer or floating-point values that specify the ambient RGBA reflectance of the material.  Inte-
			   ger values are mapped linearly such that the most positive representable value maps to 1.0, and the most negative  rep-
			   resentable  value  maps to -1.0.  Floating-point values are mapped directly.  Neither integer nor floating-point values
			   are clamped.  The initial ambient reflectance for both front- and back-facing materials is (0.2, 0.2, 0.2, 1.0).

       GL_DIFFUSE	   params contains four integer or floating-point values that specify the diffuse RGBA reflectance of the material.  Inte-
			   ger	values are mapped linearly such that the most positive representable value maps to 1.0, and the most negative rep-
			   resentable value maps to -1.0.  Floating-point values are mapped directly.  Neither integer nor  floating-point  values
			   are clamped.  The initial diffuse reflectance for both front- and back-facing materials is (0.8, 0.8, 0.8, 1.0).

       GL_SPECULAR	   params  contains  four  integer  or	floating-point	values that specify the specular RGBA reflectance of the material.
			   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 val-
			   ues are clamped.  The initial specular reflectance for both front- and back-facing materials is (0, 0, 0, 1).

       GL_EMISSION	   params contains four integer or floating-point values that specify the RGBA emitted light intensity	of  the  material.
			   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  val-
			   ues are clamped.  The initial emission intensity for both front- and back-facing materials is (0, 0, 0, 1).

       GL_SHININESS	   params  is a single integer or floating-point value that specifies the RGBA specular exponent of the material.  Integer
			   and floating-point values are mapped directly.  Only values in the range [0,128] are accepted.   The  initial  specular
			   exponent for both front- and back-facing materials is 0.

       GL_AMBIENT_AND_DIFFUSE
			   Equivalent to calling glMaterial twice with the same parameter values, once with GL_AMBIENT and once with GL_DIFFUSE.

       GL_COLOR_INDEXES    params  contains three integer or floating-point values specifying the color indices for ambient, diffuse, and specular
			   lighting.  These three values, and GL_SHININESS, are the only material values used by the  color  index  mode  lighting
			   equation.  Refer to the glLightModel reference page for a discussion of color index lighting.

NOTES

       The  material parameters can be updated at any time.  In particular, glMaterial can be called between a call to glBegin and the correspond-
       ing call to glEnd.  If only a single material parameter is to be changed per vertex, however, glColorMaterial is preferred over	glMaterial
       (see glColorMaterial).

       While  the  ambient, diffuse, specular and emission material parameters all have alpha components, only the diffuse alpha component is used
       in the lighting computation.

ERRORS

       GL_INVALID_ENUM is generated if either face or pname is not an accepted value.

       GL_INVALID_VALUE is generated if a specular exponent outside the range [0,128] is specified.

ASSOCIATED GETS

       glGetMaterial

SEE ALSO

       glColorMaterial(3G), glLight(3G), glLightModel(3G)

																    GLMATERIAL(3G)