glFragmentMaterial(3G)

NAME
     glFragmentMaterialfSGIX, glFragmentMaterialiSGIX,
     glFragmentMaterialfvSGIX, glFragmentMaterialivSGIX - specify fragment
     material parameters for the fragment lighting model


C SPECIFICATION
     void glFragmentMaterialfSGIX( GLenum face,
                                   GLenum pname,
                                   GLfloat param )
     void glFragmentMaterialiSGIX( 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 fragment 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 glFragmentMaterialfvSGIX( GLenum face,
                                    GLenum pname,
                                    const GLfloat *params )
     void glFragmentMaterialivSGIX( 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 fragment 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
     glFragmentMaterial assigns values to fragment material parameters.  There
     are two matched sets of fragment 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 glFragmentLightModel reference page for details
     concerning one- and two-sided lighting calculations.

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

     Fragment material parameters are used in the lighting equation that is
     optionally applied to each fragment.  The equation is discussed in the
     glFragmentLightModel reference page.  The parameters that can be
     specified using glFragmentMaterial, 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
                         fragment 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 values are clamped.  The initial
                         ambient reflectance for both front- and back-facing
                         fragment 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
                         fragment 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 values are clamped.  The initial
                         diffuse reflectance for both front- and back-facing
                         fragment 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
                         fragment 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 values are clamped.  The initial
                         specular reflectance for both front- and back-facing
                         fragment 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
                         fragment 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 values are clamped.  The initial
                         emission intensity for both front- and back-facing
                         fragment 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
                         fragment 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 fragment materials is
                         0.

     GL_AMBIENT_AND_DIFFUSE
                         Equivalent to calling glFragmentMaterial 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 fragment material
                         values used by the color index mode lighting
                         equation.  Refer to the glFragmentLightModel
                         reference page for a discussion of color index
                         lighting.

NOTES
     The fragment material parameters can be updated at any time.  In
     particular, glFragmentMaterial can be called between a call to glBegin
     and the corresponding call to glEnd.

     While the ambient, diffuse, specular and emission fragment 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
     glGetFragmentMaterial


MACHINE DEPENDENCIES
     The SGIX_fragment_lighting extension is supported only on Octane2 VPro
     systems.


SEE ALSO
     glFragmentColorMaterial, glFragmentLight, glFragmentLightModel