| 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> |