glGetMaterial
NAME
glGetMaterialfv, glGetMaterialiv - 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.
SEE ALSO
glMaterial