upstream-man-pages/man2/glMaterial.xml

   1 <?xml version="1.0" encoding="UTF-8"?>
   2 <!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook MathML Module V1.1b1//EN"
   3               "http://www.oasis-open.org/docbook/xml/mathml/1.1CR1/dbmathml.dtd">
   4 <refentry id="glMaterial">
   5     <refmeta>
   6         <refmetainfo>
   7             <copyright>
   8                 <year>1991-2006</year>
   9                 <holder>Silicon Graphics, Inc.</holder>
  10             </copyright>
  11         </refmetainfo>
  12         <refentrytitle>glMaterial</refentrytitle>
  13         <manvolnum>3G</manvolnum>
  14     </refmeta>
  15     <refnamediv>
  16         <refname>glMaterial</refname>
  17         <refpurpose>specify material parameters for the lighting model</refpurpose>
  18     </refnamediv>
  19     <refsynopsisdiv><title>C Specification</title>
  20         <funcsynopsis>
  21             <funcprototype>
  22                 <funcdef>void <function>glMaterialf</function></funcdef>
  23                 <paramdef>GLenum <parameter>face</parameter></paramdef>
  24                 <paramdef>GLenum <parameter>pname</parameter></paramdef>
  25                 <paramdef>GLfloat <parameter>param</parameter></paramdef>
  26             </funcprototype>
  27         </funcsynopsis>
  28         <funcsynopsis>
  29             <funcprototype>
  30                 <funcdef>void <function>glMateriali</function></funcdef>
  31                 <paramdef>GLenum <parameter>face</parameter></paramdef>
  32                 <paramdef>GLenum <parameter>pname</parameter></paramdef>
  33                 <paramdef>GLint <parameter>param</parameter></paramdef>
  34             </funcprototype>
  35         </funcsynopsis>
  36     </refsynopsisdiv>
  37     <refsect1 id="parameters"><title>Parameters</title>
  38         <variablelist>
  39         <varlistentry>
  40             <term><parameter>face</parameter></term>
  41             <listitem>
  42                 <para>
  43                     Specifies which face or faces are being updated.
  44                     Must be one of
  45                     <constant>GL_FRONT</constant>,
  46                     <constant>GL_BACK</constant>, or
  47                     <constant>GL_FRONT_AND_BACK</constant>.
  48                 </para>
  49             </listitem>
  50         </varlistentry>
  51         <varlistentry>
  52             <term><parameter>pname</parameter></term>
  53             <listitem>
  54                 <para>
  55                     Specifies the single-valued material parameter of the face or faces
  56                     that is being updated.
  57                     Must be <constant>GL_SHININESS</constant>.
  58                 </para>
  59             </listitem>
  60         </varlistentry>
  61         <varlistentry>
  62             <term><parameter>param</parameter></term>
  63             <listitem>
  64                 <para>
  65                     Specifies the value that parameter <constant>GL_SHININESS</constant> will be set to.
  66                 </para>
  67             </listitem>
  68         </varlistentry>
  69         </variablelist>
  70     </refsect1>
  71     <refsynopsisdiv><title>C Specification</title>
  72         <funcsynopsis>
  73             <funcprototype>
  74                 <funcdef>void <function>glMaterialfv</function></funcdef>
  75                 <paramdef>GLenum <parameter>face</parameter></paramdef>
  76                 <paramdef>GLenum <parameter>pname</parameter></paramdef>
  77                 <paramdef>const GLfloat * <parameter>params</parameter></paramdef>
  78             </funcprototype>
  79         </funcsynopsis>
  80         <funcsynopsis>
  81             <funcprototype>
  82                 <funcdef>void <function>glMaterialiv</function></funcdef>
  83                 <paramdef>GLenum <parameter>face</parameter></paramdef>
  84                 <paramdef>GLenum <parameter>pname</parameter></paramdef>
  85                 <paramdef>const GLint * <parameter>params</parameter></paramdef>
  86             </funcprototype>
  87         </funcsynopsis>
  88     </refsynopsisdiv>
  89     <refsect1 id="parameters2"><title>Parameters</title>
  90         <variablelist>
  91         <varlistentry>
  92             <term><parameter>face</parameter></term>
  93             <listitem>
  94                 <para>
  95                     Specifies which face or faces are being updated.
  96                     Must be one of
  97                     <constant>GL_FRONT</constant>,
  98                     <constant>GL_BACK</constant>, or
  99                     <constant>GL_FRONT_AND_BACK</constant>.
 100                 </para>
 101             </listitem>
 102         </varlistentry>
 103         <varlistentry>
 104             <term><parameter>pname</parameter></term>
 105             <listitem>
 106                 <para>
 107                     Specifies the material parameter of the face or faces that is being updated.
 108                     Must be one of
 109                     <constant>GL_AMBIENT</constant>,
 110                     <constant>GL_DIFFUSE</constant>,
 111                     <constant>GL_SPECULAR</constant>,
 112                     <constant>GL_EMISSION</constant>,
 113                     <constant>GL_SHININESS</constant>,
 114                     <constant>GL_AMBIENT_AND_DIFFUSE</constant>, or
 115                     <constant>GL_COLOR_INDEXES</constant>.
 116                 </para>
 117             </listitem>
 118         </varlistentry>
 119         <varlistentry>
 120             <term><parameter>params</parameter></term>
 121             <listitem>
 122                 <para>
 123                     Specifies a pointer to the value or values that <parameter>pname</parameter> will be set to.
 124                 </para>
 125             </listitem>
 126         </varlistentry>
 127         </variablelist>
 128     </refsect1>
 129     <refsect1 id="description"><title>Description</title>
 130         <para>
 131             <function>glMaterial</function> assigns values to material parameters.
 132             There are two matched sets of material parameters.
 133             One,
 134             the <emphasis>front-facing</emphasis> set,
 135             is used to shade points,
 136             lines,
 137             bitmaps,
 138             and all polygons
 139             (when two-sided lighting is disabled),
 140             or just front-facing polygons
 141             (when two-sided lighting is enabled).
 142             The other set,
 143             <emphasis>back-facing</emphasis>,
 144             is used to shade back-facing polygons only when two-sided lighting is enabled.
 145             Refer to the <citerefentry><refentrytitle>glLightModel</refentrytitle></citerefentry> reference page for details concerning one- and
 146             two-sided lighting calculations.
 147         </para>
 148         <para>
 149             <function>glMaterial</function> takes three arguments.
 150             The first,
 151             <parameter>face</parameter>,
 152             specifies whether the
 153             <constant>GL_FRONT</constant> materials, the
 154             <constant>GL_BACK</constant> materials, or both
 155             <constant>GL_FRONT_AND_BACK</constant> materials will be modified.
 156             The second,
 157             <parameter>pname</parameter>,
 158             specifies which of several parameters in one or both sets will be modified.
 159             The third,
 160             <parameter>params</parameter>,
 161             specifies what value or values will be assigned to the specified parameter.
 162         </para>
 163         <para>
 164             Material parameters are used in the lighting equation that is optionally
 165             applied to each vertex.
 166             The equation is discussed in the <citerefentry><refentrytitle>glLightModel</refentrytitle></citerefentry> reference page.
 167             The parameters that can be specified using <function>glMaterial</function>,
 168             and their interpretations by the lighting equation, are as follows:
 169         </para>
 170         <variablelist>
 171             <varlistentry>
 172                 <term><constant>GL_AMBIENT</constant></term>
 173                 <listitem>
 174                     <para>
 175                         <parameter>params</parameter> contains four integer or floating-point values that specify
 176                         the ambient RGBA reflectance of the material.
 177                         Integer values are mapped linearly such that the most positive representable
 178                         value maps to 1.0,
 179                         and the most negative representable value maps to
 180                         <inlineequation><mml:math>
 181                             <!-- eqn: -1.0:-->
 182                             <mml:mn>-1.0</mml:mn>
 183                         </mml:math></inlineequation>.
 184                         Floating-point values are mapped directly.
 185                         Neither integer nor floating-point values are clamped.
 186                         The initial ambient reflectance for both front- and back-facing materials
 187                         is (0.2, 0.2, 0.2, 1.0).
 188                     </para>
 189                 </listitem>
 190             </varlistentry>
 191             <varlistentry>
 192                 <term><constant>GL_DIFFUSE</constant></term>
 193                 <listitem>
 194                     <para>
 195                         <parameter>params</parameter> contains four integer or floating-point values that specify
 196                         the diffuse RGBA reflectance of the material.
 197                         Integer values are mapped linearly such that the most positive representable
 198                         value maps to 1.0,
 199                         and the most negative representable value maps to
 200                         <inlineequation><mml:math>
 201                             <!-- eqn: -1.0:-->
 202                             <mml:mn>-1.0</mml:mn>
 203                         </mml:math></inlineequation>.
 204                         Floating-point values are mapped directly.
 205                         Neither integer nor floating-point values are clamped.
 206                         The initial diffuse reflectance for both front- and back-facing materials
 207                         is (0.8, 0.8, 0.8, 1.0).
 208                     </para>
 209                 </listitem>
 210             </varlistentry>
 211             <varlistentry>
 212                 <term><constant>GL_SPECULAR</constant></term>
 213                 <listitem>
 214                     <para>
 215                         <parameter>params</parameter> contains four integer or floating-point values that specify
 216                         the specular RGBA reflectance of the material.
 217                         Integer values are mapped linearly such that the most positive representable
 218                         value maps to 1.0,
 219                         and the most negative representable value maps to
 220                         <inlineequation><mml:math>
 221                             <!-- eqn: -1.0:-->
 222                             <mml:mn>-1.0</mml:mn>
 223                         </mml:math></inlineequation>.
 224                         Floating-point values are mapped directly.
 225                         Neither integer nor floating-point values are clamped.
 226                         The initial specular reflectance for both front- and back-facing materials
 227                         is (0, 0, 0, 1).
 228                     </para>
 229                 </listitem>
 230             </varlistentry>
 231             <varlistentry>
 232                 <term><constant>GL_EMISSION</constant></term>
 233                 <listitem>
 234                     <para>
 235                         <parameter>params</parameter> contains four integer or floating-point values that specify
 236                         the RGBA emitted light intensity of the material.
 237                         Integer values are mapped linearly such that the most positive representable
 238                         value maps to 1.0,
 239                         and the most negative representable value maps to
 240                         <inlineequation><mml:math>
 241                             <!-- eqn: -1.0:-->
 242                             <mml:mn>-1.0</mml:mn>
 243                         </mml:math></inlineequation>.
 244                         Floating-point values are mapped directly.
 245                         Neither integer nor floating-point values are clamped.
 246                         The initial emission intensity for both front- and back-facing materials
 247                         is (0, 0, 0, 1).
 248                     </para>
 249                 </listitem>
 250             </varlistentry>
 251             <varlistentry>
 252                 <term><constant>GL_SHININESS</constant></term>
 253                 <listitem>
 254                     <para>
 255                         <parameter>params</parameter> is a single integer or floating-point value that specifies
 256                         the RGBA specular exponent of the material.
 257                         Integer and floating-point values are mapped directly.
 258                         Only values in the range
 259                         <inlineequation><mml:math>
 260                             <!-- eqn: [0,128]:-->
 261                             <mml:mfenced open="[" close="]">
 262                                 <mml:mn>0</mml:mn>
 263                                 <mml:mn>128</mml:mn>
 264                             </mml:mfenced>
 265                         </mml:math></inlineequation>
 266                         are accepted.
 267                         The initial specular exponent for both front- and back-facing materials
 268                         is 0.
 269                     </para>
 270                 </listitem>
 271             </varlistentry>
 272             <varlistentry>
 273                 <term><constant>GL_AMBIENT_AND_DIFFUSE</constant></term>
 274                 <listitem>
 275                     <para>
 276                         Equivalent to calling <function>glMaterial</function> twice with the same parameter values,
 277                         once with <constant>GL_AMBIENT</constant> and once with <constant>GL_DIFFUSE</constant>.
 278                     </para>
 279                 </listitem>
 280             </varlistentry>
 281             <varlistentry>
 282                 <term><constant>GL_COLOR_INDEXES</constant></term>
 283                 <listitem>
 284                     <para>
 285                         <parameter>params</parameter> contains three integer or floating-point values specifying
 286                         the color indices for ambient,
 287                         diffuse,
 288                         and specular lighting.
 289                         These three values,
 290                         and <constant>GL_SHININESS</constant>,
 291                         are the only material values used by the color index mode lighting equation.
 292                         Refer to the <citerefentry><refentrytitle>glLightModel</refentrytitle></citerefentry> reference page for a discussion
 293                         of color index lighting.
 294                     </para>
 295                 </listitem>
 296             </varlistentry>
 297         </variablelist>
 298     </refsect1>
 299     <refsect1 id="notes"><title>Notes</title>
 300         <para>
 301             The material parameters can be updated at any time.
 302             In particular,
 303             <function>glMaterial</function> can be called between a call to <citerefentry><refentrytitle>glBegin</refentrytitle></citerefentry> and the corresponding
 304             call to <citerefentry><refentrytitle>glEnd</refentrytitle></citerefentry>.
 305             If only a single material parameter is to be changed per vertex,
 306             however,
 307             <citerefentry><refentrytitle>glColorMaterial</refentrytitle></citerefentry> is preferred over <function>glMaterial</function>
 308             (see <citerefentry><refentrytitle>glColorMaterial</refentrytitle></citerefentry>).
 309         </para>
 310         <para>
 311             While the ambient, diffuse, specular and emission material parameters
 312             all have alpha components, only the diffuse alpha component is used in
 313             the lighting computation.
 314         </para>
 315     </refsect1>
 316     <refsect1 id="errors"><title>Errors</title>
 317         <para>
 318             <constant>GL_INVALID_ENUM</constant> is generated if either <parameter>face</parameter> or <parameter>pname</parameter> is not
 319             an accepted value.
 320         </para>
 321         <para>
 322             <constant>GL_INVALID_VALUE</constant> is generated if a specular exponent outside the range
 323             <inlineequation><mml:math>
 324                 <!-- eqn: [0,128]:-->
 325                 <mml:mfenced open="[" close="]">
 326                     <mml:mn>0</mml:mn>
 327                     <mml:mn>128</mml:mn>
 328                 </mml:mfenced>
 329             </mml:math></inlineequation>
 330             is specified.
 331         </para>
 332     </refsect1>
 333     <refsect1 id="associatedgets"><title>Associated Gets</title>
 334         <para>
 335             <citerefentry><refentrytitle>glGetMaterial</refentrytitle></citerefentry>
 336         </para>
 337     </refsect1>
 338     <refsect1 id="seealso"><title>See Also</title>
 339         <para>
 340             <citerefentry><refentrytitle>glColorMaterial</refentrytitle></citerefentry>,
 341             <citerefentry><refentrytitle>glLight</refentrytitle></citerefentry>,
 342             <citerefentry><refentrytitle>glLightModel</refentrytitle></citerefentry>
 343         </para>
 344     </refsect1>
 345     <refsect1 id="Copyright"><title>Copyright</title>
 346         <para>
 347             Copyright <trademark class="copyright"></trademark> 1991-2006
 348             Silicon Graphics, Inc. This document is licensed under the SGI
 349             Free Software B License. For details, see
 350             <ulink url="http://oss.sgi.com/projects/FreeB/">http://oss.sgi.com/projects/FreeB/</ulink>.
 351         </para>
 352     </refsect1>
 353 </refentry>