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glGetMaterial.3gl

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.

SEE ALSO

glMaterial(3G)