Интерактивная система просмотра системных руководств (man-ов)
glGetMaterial (3)
>> glGetMaterial (3) ( Разные man: Библиотечные вызовы )
NAME
glGetMaterialfv, glGetMaterialiv
- return material parameters
C SPECIFICATION
void glGetMaterialfv(
GLenum face,
GLenum pname,
GLfloat *params )
void glGetMaterialiv(
GLenum face,
GLenum pname,
GLint *params )
delim $$
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, 1.0],
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 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.
