glGetMaterialfv, glGetMaterialiv − return material parameters
void glGetMaterialfv( GLenum face,
GLenum pname, 

GLfloat *params ) 
void glGetMaterialiv( GLenum face,
GLenum pname, 

GLint *params ) 
face 
Specifies which of the two materials is being queried. GL_FRONT or GL_BACK are accepted, representing the front and back materials, respectively. 

pname 
Specifies the 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. 
glGetMaterial returns in params the value or values of parameter pname of material face. Six parameters are defined:
GL_AMBIENT 
params returns four integer or floatingpoint values representing the ambient reflectance of the material. Integer values, when requested, are linearly mapped from the internal floatingpoint 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 floatingpoint values representing the diffuse reflectance of the material. Integer values, when requested, are linearly mapped from the internal floatingpoint 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 floatingpoint values representing the specular reflectance of the material. Integer values, when requested, are linearly mapped from the internal floatingpoint 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 floatingpoint values representing the emitted light intensity of the material. Integer values, when requested, are linearly mapped from the internal floatingpoint 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 floatingpoint value representing the specular exponent of the material. Integer values, when requested, are computed by rounding the internal floatingpoint value to the nearest integer value. The initial value is 0. 

GL_COLOR_INDEXES 
params returns three integer or floatingpoint values representing the ambient, diffuse, and specular indices of the 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 floatingpoint values to the nearest integer values. 
If an error is generated, no change is made to the contents of params.
GL_INVALID_ENUM is generated if face or pname is not an accepted value.
GL_INVALID_OPERATION is generated if glGetMaterial is executed between the execution of glBegin and the corresponding execution of glEnd.