glGetFragmentMaterial(3G)

NAME
     glGetFragmentMaterialfvSGIX, glGetFragmentMaterialivSGIX - return
     fragment material parameters


C SPECIFICATION
     void glGetFragmentMaterialfvSGIX( GLenum face,
                                       GLenum pname,
                                       GLfloat *params )
     void glGetFragmentMaterialivSGIX( GLenum face,
                                       GLenum pname,
                                       GLint *params )


PARAMETERS
     face    Specifies which of the two fragment materials is being queried.
             GL_FRONT or GL_BACK are accepted, representing the front and back
             fragment materials, respectively.

     pname   Specifies the fragment material parameter to return.  GL_AMBIENT,
             GL_DIFFUSE, GL_SPECULAR, GL_EMISSION, GL_SHININESS, and
             GL_COLOR_INDEXES are accepted.

     params  Returns the requested data.

DESCRIPTION
     glGetFragmentMaterial returns in params the value or values of parameter
     pname of fragment material face. Six parameters are defined:

     GL_AMBIENT            params returns four integer or floating-point
                           values representing the ambient reflectance of the
                           fragment material.  Integer values, when requested,
                           are linearly mapped from the internal floating-
                           point representation such that 1.0 maps to the most
                           positive representable integer value, and -1.0 maps
                           to the most negative representable integer value.
                           If the internal value is outside the range [-1, 1],
                           the corresponding integer return value is
                           undefined. The initial value is (0.2, 0.2, 0.2,
                           1.0)

     GL_DIFFUSE            params returns four integer or floating-point
                           values representing the diffuse reflectance of the
                           fragment material.  Integer values, when requested,
                           are linearly mapped from the internal floating-
                           point representation such that 1.0 maps to the most
                           positive representable integer value, and -1.0 maps
                           to the most negative representable integer value.
                           If the internal value is outside the range [-1, 1],
                           the corresponding integer return value is
                           undefined. The initial value is (0.8, 0.8, 0.8,
                           1.0).
     GL_SPECULAR           params returns four integer or floating-point
                           values representing the specular reflectance of the
                           fragment material.  Integer values, when requested,
                           are linearly mapped from the internal floating-
                           point representation such that 1.0 maps to the most
                           positive representable integer value, and -1.0 maps
                           to the most negative representable integer value.
                           If the internal value is outside the range [-1, 1],
                           the corresponding integer return value is
                           undefined. The initial value is (0, 0, 0, 1).

     GL_EMISSION           params returns four integer or floating-point
                           values representing the emitted light intensity of
                           the fragment material.  Integer values, when
                           requested, are linearly mapped from the internal
                           floating-point representation such that 1.0 maps to
                           the most positive representable integer value, and
                           -1.0 maps to the most negative representable
                           integer value.  If the internal value is outside
                           the range [-1, 1.0], the corresponding integer
                           return value is undefined. The initial value is (0,
                           0, 0, 1).

     GL_SHININESS          params returns one integer or floating-point value
                           representing the specular exponent of the fragment
                           material.  Integer values, when requested, are
                           computed by rounding the internal floating-point
                           value to the nearest integer value. The initial
                           value is 0.

     GL_COLOR_INDEXES      params returns three integer or floating-point
                           values representing the ambient, diffuse, and
                           specular indices of the fragment material.  These
                           indices are used only for color index lighting.
                           (All the other parameters are used only for RGBA
                           lighting.)  Integer values, when requested, are
                           computed by rounding the internal floating-point
                           values to the nearest integer values.

NOTES
     If an error is generated, no change is made to the contents of params.

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

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

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


SEE ALSO
     glFragmentMaterial