glMaterial man page on RedHat
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GLMATERIAL(3G) OpenGL Manual GLMATERIAL(3G)
NAME
glMaterial - specify material parameters for the lighting model
C SPECIFICATION
void glMaterialf(GLenum face, GLenum pname, GLfloat param);
void glMateriali(GLenum face, GLenum pname, GLint param);
PARAMETERS
face
Specifies which face or faces are being updated. Must be one of
GL_FRONT, GL_BACK, or GL_FRONT_AND_BACK.
pname
Specifies the single-valued material parameter of the face or faces
that is being updated. Must be GL_SHININESS.
param
Specifies the value that parameter GL_SHININESS will be set to.
C SPECIFICATION
void glMaterialfv(GLenum face, GLenum pname, const GLfloat * params);
void glMaterialiv(GLenum face, GLenum pname, const GLint * params);
PARAMETERS
face
Specifies which face or faces are being updated. Must be one of
GL_FRONT, GL_BACK, or GL_FRONT_AND_BACK.
pname
Specifies the material parameter 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.
params
Specifies a pointer to the value or values that pname will be set
to.
DESCRIPTION
glMaterial 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,
specifies 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
optionally applied to each vertex. The equation is discussed in the
glLightModel() reference page. The parameters that can be specified
using glMaterial, and their interpretations by the lighting equation,
are as follows:
GL_AMBIENT
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 floating-point values are clamped. The initial ambient
reflectance for both front- and back-facing materials is (0.2, 0.2,
0.2, 1.0).
GL_DIFFUSE
params contains 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-facing materials is (0.8, 0.8,
0.8, 1.0).
GL_SPECULAR
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 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 specular
reflectance for both front- and back-facing materials is (0, 0, 0,
1).
GL_EMISSION
params contains four integer or floating-point values that specify
the RGBA emitted light intensity 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 emission
intensity for both front- and back-facing materials is (0, 0, 0,
1).
GL_SHININESS
params is a single integer or floating-point value that specifies
the RGBA specular exponent 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.
GL_AMBIENT_AND_DIFFUSE
Equivalent to calling glMaterial twice with the same parameter
values, once with GL_AMBIENT and once with GL_DIFFUSE.
GL_COLOR_INDEXES
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
corresponding call to glEnd(). If only a single material parameter is
to be changed per vertex, however, glColorMaterial() is preferred over
glMaterial (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 GETS
glGetMaterial()
SEE ALSO
glColorMaterial(), glLight(), glLightModel()
COPYRIGHT
Copyright © 1991-2006 Silicon Graphics, Inc. This document is licensed
under the SGI Free Software B License. For details, see
http://oss.sgi.com/projects/FreeB/.
AUTHORS
opengl.org
opengl.org 03/16/2013 GLMATERIAL(3G)
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