NAME¶
glGetMaterial - return material parameters
C SPECIFICATION¶
void glGetMaterialfv(GLenum face,
GLenum pname,
GLfloat * params);
void glGetMaterialiv(GLenum face,
GLenum pname,
GLint * params);
PARAMETERS¶
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.
DESCRIPTION¶
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 floating-point
values representing the ambient reflectance of the 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 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 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 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_SHININESS
params returns one integer or floating-point value
representing the specular exponent of the 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
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 glGetMaterial
is executed between the execution of glBegin() and the corresponding
execution of glEnd().