glMaterial(3G)glMaterial(3G)NAME
glMaterial, glMaterialf, glMateriali, glMaterialfv, glMaterialiv -
specify material parameters for the lighting model
SYNOPSIS
void glMaterialf(
GLenum face,
GLenum pname,
GLfloat param ); void glMateriali(
GLenum face,
GLenum pname,
GLint param );
PARAMETERS
Specifies which face or faces are being updated. Must be one of
GL_FRONT, GL_BACK, or GL_FRONT_AND_BACK. Specifies the single-valued
material parameter of the face or faces that is being updated. Must be
GL_SHININESS. Specifies the value that parameter GL_SHININESS will be
set to.
SYNOPSIS
void glMaterialfv(
GLenum face,
GLenum pname,
const GLfloat *params ); void glMaterialiv(
GLenum face,
GLenum pname,
const GLint *params );
PARAMETERS
Specifies which face or faces are being updated. Must be one of
GL_FRONT, GL_BACK, or GL_FRONT_AND_BACK. Specifies the material param‐
eter of the face or faces that is being updated. Must be one of
GL_AMBIENT, GL_DIFFUSE, GL_SPECULAR, GL_EMISSION, GL_SHININESS,
GL_AMBIENT_AND_DIFFUSE, or GL_COLOR_INDEXES. Specifies a pointer to
the value or values that pname will be set to.
DESCRIPTIONglMaterial() assigns values to material parameters. There are two
matched sets of material parameters. One, the front-facing set, is used
to shade points, lines, bitmaps, and all polygons (when two-sided
lighting is disabled), or just front-facing polygons (when two-sided
lighting is enabled). The other set, back-facing, is used to shade
back-facing polygons only when two-sided lighting is enabled. Refer to
the glLightModel() reference page for details concerning one- and two-
sided lighting calculations.
glMaterial() takes three arguments. The first, face, specifies whether
the GL_FRONT materials, the GL_BACK materials, or both
GL_FRONT_AND_BACK materials will be modified. The second, pname, speci‐
fies which of several parameters in one or both sets will be modified.
The third, params, specifies what value or values will be assigned to
the specified parameter.
Material parameters are used in the lighting equation that is option‐
ally applied to each vertex. The equation is discussed in the glLight‐
Model() reference page. The parameters that can be specified using
glMaterial(), and their interpretations by the lighting equation, are
as follows: params contains four integer or floating-point values that
specify the ambient RGBA reflectance of the material. Integer values
are mapped linearly such that the most positive representable value
maps to 1.0, and the most negative representable value maps to -1.0.
Floating-point values are mapped directly. Neither integer nor float‐
ing-point values are clamped. The initial ambient reflectance for both
front- and back-facing materials is (0.2, 0.2, 0.2, 1.0). params con‐
tains four integer or floating-point values that specify the diffuse
RGBA reflectance of the material. Integer values are mapped linearly
such that the most positive representable value maps to 1.0, and the
most negative representable value maps to -1.0. Floating-point values
are mapped directly. Neither integer nor floating-point values are
clamped. The initial diffuse reflectance for both front- and back-fac‐
ing materials is (0.8, 0.8, 0.8, 1.0). params contains four integer or
floating-point values that specify the specular RGBA reflectance of the
material. Integer values are mapped linearly such that the most posi‐
tive representable value maps to 1.0, and the most negative repre‐
sentable value maps to -1.0. Floating-point values are mapped directly.
Neither integer nor floating-point values are clamped. The initial
specular reflectance for both front- and back-facing materials is (0,
0, 0, 1). params contains four integer or floating-point values that
specify the RGBA emitted light intensity of the material. Integer val‐
ues are mapped linearly such that the most positive representable value
maps to 1.0, and the most negative representable value maps to -1.0.
Floating-point values are mapped directly. Neither integer nor float‐
ing-point values are clamped. The initial emission intensity for both
front- and back-facing materials is (0, 0, 0, 1). params is a single
integer or floating-point value that specifies the RGBA specular expo‐
nent of the material. Integer and floating-point values are mapped
directly. Only values in the range [0,128] are accepted. The initial
specular exponent for both front- and back-facing materials is 0.
Equivalent to calling glMaterial() twice with the same parameter val‐
ues, once with GL_AMBIENT and once with GL_DIFFUSE. params contains
three integer or floating-point values specifying the color indices for
ambient, diffuse, and specular lighting. These three values, and
GL_SHININESS, are the only material values used by the color index mode
lighting equation. Refer to the glLightModel() reference page for a
discussion of color index lighting.
NOTES
The material parameters can be updated at any time. In particular,
glMaterial() can be called between a call to glBegin() and the corre‐
sponding call to glEnd(). If only a single material parameter is to be
changed per vertex, however, glColorMaterial() is preferred over glMa‐
terial() (see glColorMaterial()).
While the ambient, diffuse, specular and emission material parameters
all have alpha components, only the diffuse alpha component is used in
the lighting computation.
ERRORS
GL_INVALID_ENUM is generated if either face or pname is not an accepted
value.
GL_INVALID_VALUE is generated if a specular exponent outside the range
[0,128] is specified.
ASSOCIATED GETSglGetMaterial()SEE ALSOglColorMaterial(3), glLight(3), glLightModel(3)glMaterial(3G)