_C_ License Applicability. Except to the extent portions of this file are
_C_ made subject to an alternative license as permitted in the SGI Free
_C_ Software License B, Version 1.1 (the "License"), the contents of this
_C_ file are subject only to the provisions of the License. You may not use
_C_ this file except in compliance with the License. You may obtain a copy
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_C_ http://oss.sgi.com/projects/FreeB
_C_ 
_C_ Note that, as provided in the License, the Software is distributed on an
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_C_ 
_C_ Original Code. The Original Code is: OpenGL Sample Implementation,
_C_ Version 1.2.1, released January 26, 2000, developed by Silicon Graphics,
_C_ Inc. The Original Code is Copyright (c) 1991-2000 Silicon Graphics, Inc.
_C_ Copyright in any portions created by third parties is as indicated
_C_ elsewhere herein. All Rights Reserved.
_C_ 
_C_ Additional Notice Provisions: The application programming interfaces
_C_ established by SGI in conjunction with the Original Code are The
_C_ OpenGL(R) Graphics System: A Specification (Version 1.2.1), released
_C_ April 1, 1999; The OpenGL(R) Graphics System Utility Library (Version
_C_ 1.3), released November 4, 1998; and OpenGL(R) Graphics with the X
_C_ Window System(R) (Version 1.3), released October 19, 1998. This software
_C_ was created using the OpenGL(R) version 1.2.1 Sample Implementation
_C_ published by SGI, but has not been independently verified as being
_C_ compliant with the OpenGL(R) version 1.2.1 Specification.
_C_
_C_ $Date$ $Revision$
_C_ The first character in this file must be an '_'!
_C_ Anything on a line after _C_ is ignored
_define(_filters,eqn)_C_
_C_      eqn is automatically replaced with neqn for nroff
_header(GetMaterial,return material parameters)
_names(GetMaterial,[fi]v)
.EQ
delim $$
.EN
.SH PARAMETERS
_phead(_param1)
Specifies which of the two materials is being queried.
_const(FRONT) or _const(BACK) are accepted,
representing the front and back materials, respectively.
_phead(_param2)
Specifies the material parameter to return.
_const(AMBIENT),
_const(DIFFUSE),
_const(SPECULAR),
_const(EMISSION), 
_const(SHININESS), and
_const(COLOR_INDEXES)
are accepted.
_phead(_param3)
Returns the requested data.
.SH DESCRIPTION
_cmnd returns in _param3 the value or values of parameter _param2
of material _param1. Six parameters are defined:
.TP 22
_const(AMBIENT)
_param3 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)
.TP
_const(DIFFUSE)
_param3 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).
.TP
_const(SPECULAR)
_param3 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).
.TP
_const(EMISSION)
_param3 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). 
.TP
_const(SHININESS)
_param3 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. 
.TP
_const(COLOR_INDEXES)
_param3 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.
.SH NOTES
If an error is generated,
no change is made to the contents of _param3.
.SH ERRORS
_const(INVALID_ENUM) is generated if _param1 or _param2 is not an
accepted value.
.P
_const(INVALID_OPERATION) is generated if _cmnd
is executed between the execution of _cmnd(Begin)
and the corresponding execution of _cmnd(End).
.SH SEE ALSO
_cmnd(Material)
