| 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="glBlendEquation"> |
| 5 | <refmeta> |
| 6 | <refmetainfo> |
| 7 | <copyright> |
| 8 | <year>1991-2006</year> |
| 9 | <holder>Silicon Graphics, Inc.</holder> |
| 10 | </copyright> |
| 11 | </refmetainfo> |
| 12 | <refentrytitle>glBlendEquation</refentrytitle> |
| 13 | <manvolnum>3G</manvolnum> |
| 14 | </refmeta> |
| 15 | <refnamediv> |
| 16 | <refname>glBlendEquation</refname> |
| 17 | <refpurpose>specify the equation used for both the RGB blend equation and the Alpha blend equation</refpurpose> |
| 18 | </refnamediv> |
| 19 | <refsynopsisdiv><title>C Specification</title> |
| 20 | <funcsynopsis> |
| 21 | <funcprototype> |
| 22 | <funcdef>void <function>glBlendEquation</function></funcdef> |
| 23 | <paramdef>GLenum <parameter>mode</parameter></paramdef> |
| 24 | </funcprototype> |
| 25 | <funcprototype> |
| 26 | <funcdef>void <function>glBlendEquationi</function></funcdef> |
| 27 | <paramdef>GLuint <parameter>buf</parameter></paramdef> |
| 28 | <paramdef>GLenum <parameter>mode</parameter></paramdef> |
| 29 | </funcprototype> |
| 30 | </funcsynopsis> |
| 31 | </refsynopsisdiv> |
| 32 | <!-- eqn: ignoring delim $$ --> |
| 33 | <refsect1 id="parameters"><title>Parameters</title> |
| 34 | <variablelist> |
| 35 | <varlistentry> |
| 36 | <term><parameter>buf</parameter></term> |
| 37 | <listitem> |
| 38 | <para> |
| 39 | for <function>glBlendEquationi</function>, specifies the index of the draw buffer |
| 40 | for which to set the blend equation. |
| 41 | </para> |
| 42 | </listitem> |
| 43 | </varlistentry> |
| 44 | <varlistentry> |
| 45 | <term><parameter>mode</parameter></term> |
| 46 | <listitem> |
| 47 | <para> |
| 48 | specifies how source and destination colors are combined. |
| 49 | It must be <constant>GL_FUNC_ADD</constant>, <constant>GL_FUNC_SUBTRACT</constant>, |
| 50 | <constant>GL_FUNC_REVERSE_SUBTRACT</constant>, <constant>GL_MIN</constant>, <constant>GL_MAX</constant>. |
| 51 | </para> |
| 52 | </listitem> |
| 53 | </varlistentry> |
| 54 | </variablelist> |
| 55 | </refsect1> |
| 56 | <refsect1 id="description"><title>Description</title> |
| 57 | <para> |
| 58 | The blend equations determine how a new pixel (the ''source'' color) |
| 59 | is combined with a pixel already in the framebuffer (the ''destination'' |
| 60 | color). This function sets both the RGB blend equation and the alpha |
| 61 | blend equation to a single equation. <function>glBlendEquationi</function> |
| 62 | specifies the blend equation for a single draw buffer whereas <function>glBlendEquation</function> |
| 63 | sets the blend equation for all draw buffers. |
| 64 | </para> |
| 65 | <para> |
| 66 | These equations use the source and destination blend factors |
| 67 | specified by either <citerefentry><refentrytitle>glBlendFunc</refentrytitle></citerefentry> or |
| 68 | <citerefentry><refentrytitle>glBlendFuncSeparate</refentrytitle></citerefentry>. |
| 69 | See <citerefentry><refentrytitle>glBlendFunc</refentrytitle></citerefentry> or <citerefentry><refentrytitle>glBlendFuncSeparate</refentrytitle></citerefentry> |
| 70 | for a description of the various blend factors. |
| 71 | </para> |
| 72 | <para> |
| 73 | In the equations that follow, source and destination |
| 74 | color components are referred to as |
| 75 | <inlineequation><mml:math> |
| 76 | <!-- eqn: ( R sub s, G sub s, B sub s, A sub s ): --> |
| 77 | <mml:mfenced open="(" close=")"> |
| 78 | <mml:msub><mml:mi mathvariant="italic">R</mml:mi> |
| 79 | <mml:mi mathvariant="italic">s</mml:mi> |
| 80 | </mml:msub> |
| 81 | <mml:msub><mml:mi mathvariant="italic">G</mml:mi> |
| 82 | <mml:mi mathvariant="italic">s</mml:mi> |
| 83 | </mml:msub> |
| 84 | <mml:msub><mml:mi mathvariant="italic">B</mml:mi> |
| 85 | <mml:mi mathvariant="italic">s</mml:mi> |
| 86 | </mml:msub> |
| 87 | <mml:msub><mml:mi mathvariant="italic">A</mml:mi> |
| 88 | <mml:mi mathvariant="italic">s</mml:mi> |
| 89 | </mml:msub> |
| 90 | </mml:mfenced> |
| 91 | </mml:math></inlineequation> |
| 92 | and |
| 93 | <inlineequation><mml:math> |
| 94 | <!-- eqn: ( R sub d, G sub d, B sub d, A sub d ): --> |
| 95 | <mml:mfenced open="(" close=")"> |
| 96 | <mml:msub><mml:mi mathvariant="italic">R</mml:mi> |
| 97 | <mml:mi mathvariant="italic">d</mml:mi> |
| 98 | </mml:msub> |
| 99 | <mml:msub><mml:mi mathvariant="italic">G</mml:mi> |
| 100 | <mml:mi mathvariant="italic">d</mml:mi> |
| 101 | </mml:msub> |
| 102 | <mml:msub><mml:mi mathvariant="italic">B</mml:mi> |
| 103 | <mml:mi mathvariant="italic">d</mml:mi> |
| 104 | </mml:msub> |
| 105 | <mml:msub><mml:mi mathvariant="italic">A</mml:mi> |
| 106 | <mml:mi mathvariant="italic">d</mml:mi> |
| 107 | </mml:msub> |
| 108 | </mml:mfenced> |
| 109 | </mml:math></inlineequation>, |
| 110 | respectively. |
| 111 | The result color is referred to as |
| 112 | <inlineequation><mml:math> |
| 113 | <!-- eqn: ( R sub r, G sub r, B sub r, A sub r ): --> |
| 114 | <mml:mfenced open="(" close=")"> |
| 115 | <mml:msub><mml:mi mathvariant="italic">R</mml:mi> |
| 116 | <mml:mi mathvariant="italic">r</mml:mi> |
| 117 | </mml:msub> |
| 118 | <mml:msub><mml:mi mathvariant="italic">G</mml:mi> |
| 119 | <mml:mi mathvariant="italic">r</mml:mi> |
| 120 | </mml:msub> |
| 121 | <mml:msub><mml:mi mathvariant="italic">B</mml:mi> |
| 122 | <mml:mi mathvariant="italic">r</mml:mi> |
| 123 | </mml:msub> |
| 124 | <mml:msub><mml:mi mathvariant="italic">A</mml:mi> |
| 125 | <mml:mi mathvariant="italic">r</mml:mi> |
| 126 | </mml:msub> |
| 127 | </mml:mfenced> |
| 128 | </mml:math></inlineequation>. |
| 129 | The source and destination blend factors are denoted |
| 130 | <inlineequation><mml:math> |
| 131 | <!-- eqn: ( s sub R, s sub G, s sub B, s sub A ): --> |
| 132 | <mml:mfenced open="(" close=")"> |
| 133 | <mml:msub><mml:mi mathvariant="italic">s</mml:mi> |
| 134 | <mml:mi mathvariant="italic">R</mml:mi> |
| 135 | </mml:msub> |
| 136 | <mml:msub><mml:mi mathvariant="italic">s</mml:mi> |
| 137 | <mml:mi mathvariant="italic">G</mml:mi> |
| 138 | </mml:msub> |
| 139 | <mml:msub><mml:mi mathvariant="italic">s</mml:mi> |
| 140 | <mml:mi mathvariant="italic">B</mml:mi> |
| 141 | </mml:msub> |
| 142 | <mml:msub><mml:mi mathvariant="italic">s</mml:mi> |
| 143 | <mml:mi mathvariant="italic">A</mml:mi> |
| 144 | </mml:msub> |
| 145 | </mml:mfenced> |
| 146 | </mml:math></inlineequation> |
| 147 | and |
| 148 | <inlineequation><mml:math> |
| 149 | <!-- eqn: ( d sub R, d sub G, d sub B, d sub A ): --> |
| 150 | <mml:mfenced open="(" close=")"> |
| 151 | <mml:msub><mml:mi mathvariant="italic">d</mml:mi> |
| 152 | <mml:mi mathvariant="italic">R</mml:mi> |
| 153 | </mml:msub> |
| 154 | <mml:msub><mml:mi mathvariant="italic">d</mml:mi> |
| 155 | <mml:mi mathvariant="italic">G</mml:mi> |
| 156 | </mml:msub> |
| 157 | <mml:msub><mml:mi mathvariant="italic">d</mml:mi> |
| 158 | <mml:mi mathvariant="italic">B</mml:mi> |
| 159 | </mml:msub> |
| 160 | <mml:msub><mml:mi mathvariant="italic">d</mml:mi> |
| 161 | <mml:mi mathvariant="italic">A</mml:mi> |
| 162 | </mml:msub> |
| 163 | </mml:mfenced> |
| 164 | </mml:math></inlineequation>, |
| 165 | respectively. |
| 166 | For these equations all color components are understood to have values |
| 167 | in the range |
| 168 | <inlineequation><mml:math> |
| 169 | <!-- eqn: [0,1]: --> |
| 170 | <mml:mfenced open="[" close="]"> |
| 171 | <mml:mn>0</mml:mn> |
| 172 | <mml:mn>1</mml:mn> |
| 173 | </mml:mfenced> |
| 174 | </mml:math></inlineequation>. |
| 175 | |
| 176 | <informaltable frame="topbot"> |
| 177 | <tgroup cols="3" align="left"> |
| 178 | <colspec colwidth="1.1*" /> |
| 179 | <colspec colwidth="1*" /> |
| 180 | <colspec colwidth="1*" /> |
| 181 | <thead> |
| 182 | <row> |
| 183 | <entry rowsep="1" align="left"><emphasis role="bold"> |
| 184 | Mode |
| 185 | </emphasis></entry> |
| 186 | <entry rowsep="1" align="left"><emphasis role="bold"> |
| 187 | RGB Components |
| 188 | </emphasis></entry> |
| 189 | <entry rowsep="1" align="left"><emphasis role="bold"> |
| 190 | Alpha Component |
| 191 | </emphasis></entry> |
| 192 | </row> |
| 193 | </thead> |
| 194 | <tbody> |
| 195 | <row> |
| 196 | <entry align="left"> |
| 197 | <constant>GL_FUNC_ADD</constant> |
| 198 | </entry> |
| 199 | <entry align="left"> |
| 200 | <informalequation><mml:math> |
| 201 | <!-- eqn: Rr = R sub s s sub R + R sub d d sub R : --> |
| 202 | <mml:mrow> |
| 203 | <mml:mi mathvariant="italic">Rr</mml:mi> |
| 204 | <mml:mo>=</mml:mo> |
| 205 | <mml:mrow> |
| 206 | <mml:msub><mml:mi mathvariant="italic">R</mml:mi> |
| 207 | <mml:mi mathvariant="italic">s</mml:mi> |
| 208 | </mml:msub> |
| 209 | <mml:mo>⁢</mml:mo> |
| 210 | <mml:msub><mml:mi mathvariant="italic">s</mml:mi> |
| 211 | <mml:mi mathvariant="italic">R</mml:mi> |
| 212 | </mml:msub> |
| 213 | <mml:mo>+</mml:mo> |
| 214 | <mml:msub><mml:mi mathvariant="italic">R</mml:mi> |
| 215 | <mml:mi mathvariant="italic">d</mml:mi> |
| 216 | </mml:msub> |
| 217 | <mml:mo>⁢</mml:mo> |
| 218 | <mml:msub><mml:mi mathvariant="italic">d</mml:mi> |
| 219 | <mml:mi mathvariant="italic">R</mml:mi> |
| 220 | </mml:msub> |
| 221 | </mml:mrow> |
| 222 | </mml:mrow> |
| 223 | </mml:math></informalequation> |
| 224 | <informalequation><mml:math> |
| 225 | <!-- eqn: Gr = G sub s s sub G + G sub d d sub G : --> |
| 226 | <mml:mrow> |
| 227 | <mml:mi mathvariant="italic">Gr</mml:mi> |
| 228 | <mml:mo>=</mml:mo> |
| 229 | <mml:mrow> |
| 230 | <mml:msub><mml:mi mathvariant="italic">G</mml:mi> |
| 231 | <mml:mi mathvariant="italic">s</mml:mi> |
| 232 | </mml:msub> |
| 233 | <mml:mo>⁢</mml:mo> |
| 234 | <mml:msub><mml:mi mathvariant="italic">s</mml:mi> |
| 235 | <mml:mi mathvariant="italic">G</mml:mi> |
| 236 | </mml:msub> |
| 237 | <mml:mo>+</mml:mo> |
| 238 | <mml:msub><mml:mi mathvariant="italic">G</mml:mi> |
| 239 | <mml:mi mathvariant="italic">d</mml:mi> |
| 240 | </mml:msub> |
| 241 | <mml:mo>⁢</mml:mo> |
| 242 | <mml:msub><mml:mi mathvariant="italic">d</mml:mi> |
| 243 | <mml:mi mathvariant="italic">G</mml:mi> |
| 244 | </mml:msub> |
| 245 | </mml:mrow> |
| 246 | </mml:mrow> |
| 247 | </mml:math></informalequation> |
| 248 | <informalequation><mml:math> |
| 249 | <!-- eqn: Br = B sub s s sub B + B sub d d sub B : --> |
| 250 | <mml:mrow> |
| 251 | <mml:mi mathvariant="italic">Br</mml:mi> |
| 252 | <mml:mo>=</mml:mo> |
| 253 | <mml:mrow> |
| 254 | <mml:msub><mml:mi mathvariant="italic">B</mml:mi> |
| 255 | <mml:mi mathvariant="italic">s</mml:mi> |
| 256 | </mml:msub> |
| 257 | <mml:mo>⁢</mml:mo> |
| 258 | <mml:msub><mml:mi mathvariant="italic">s</mml:mi> |
| 259 | <mml:mi mathvariant="italic">B</mml:mi> |
| 260 | </mml:msub> |
| 261 | <mml:mo>+</mml:mo> |
| 262 | <mml:msub><mml:mi mathvariant="italic">B</mml:mi> |
| 263 | <mml:mi mathvariant="italic">d</mml:mi> |
| 264 | </mml:msub> |
| 265 | <mml:mo>⁢</mml:mo> |
| 266 | <mml:msub><mml:mi mathvariant="italic">d</mml:mi> |
| 267 | <mml:mi mathvariant="italic">B</mml:mi> |
| 268 | </mml:msub> |
| 269 | </mml:mrow> |
| 270 | </mml:mrow> |
| 271 | </mml:math></informalequation> |
| 272 | </entry> |
| 273 | <entry align="left"> |
| 274 | <informalequation><mml:math> |
| 275 | <!-- eqn: Ar = A sub s s sub A + A sub d d sub A : --> |
| 276 | <mml:mrow> |
| 277 | <mml:mi mathvariant="italic">Ar</mml:mi> |
| 278 | <mml:mo>=</mml:mo> |
| 279 | <mml:mrow> |
| 280 | <mml:msub><mml:mi mathvariant="italic">A</mml:mi> |
| 281 | <mml:mi mathvariant="italic">s</mml:mi> |
| 282 | </mml:msub> |
| 283 | <mml:mo>⁢</mml:mo> |
| 284 | <mml:msub><mml:mi mathvariant="italic">s</mml:mi> |
| 285 | <mml:mi mathvariant="italic">A</mml:mi> |
| 286 | </mml:msub> |
| 287 | <mml:mo>+</mml:mo> |
| 288 | <mml:msub><mml:mi mathvariant="italic">A</mml:mi> |
| 289 | <mml:mi mathvariant="italic">d</mml:mi> |
| 290 | </mml:msub> |
| 291 | <mml:mo>⁢</mml:mo> |
| 292 | <mml:msub><mml:mi mathvariant="italic">d</mml:mi> |
| 293 | <mml:mi mathvariant="italic">A</mml:mi> |
| 294 | </mml:msub> |
| 295 | </mml:mrow> |
| 296 | </mml:mrow> |
| 297 | </mml:math></informalequation> |
| 298 | </entry> |
| 299 | </row> |
| 300 | <row> |
| 301 | <entry align="left"> |
| 302 | <constant>GL_FUNC_SUBTRACT</constant> |
| 303 | </entry> |
| 304 | <entry align="left"> |
| 305 | <informalequation><mml:math> |
| 306 | <!-- eqn: Rr = R sub s s sub R - R sub d d sub R : --> |
| 307 | <mml:mrow> |
| 308 | <mml:mi mathvariant="italic">Rr</mml:mi> |
| 309 | <mml:mo>=</mml:mo> |
| 310 | <mml:mrow> |
| 311 | <mml:msub><mml:mi mathvariant="italic">R</mml:mi> |
| 312 | <mml:mi mathvariant="italic">s</mml:mi> |
| 313 | </mml:msub> |
| 314 | <mml:mo>⁢</mml:mo> |
| 315 | <mml:msub><mml:mi mathvariant="italic">s</mml:mi> |
| 316 | <mml:mi mathvariant="italic">R</mml:mi> |
| 317 | </mml:msub> |
| 318 | <mml:mo>-</mml:mo> |
| 319 | <mml:msub><mml:mi mathvariant="italic">R</mml:mi> |
| 320 | <mml:mi mathvariant="italic">d</mml:mi> |
| 321 | </mml:msub> |
| 322 | <mml:mo>⁢</mml:mo> |
| 323 | <mml:msub><mml:mi mathvariant="italic">d</mml:mi> |
| 324 | <mml:mi mathvariant="italic">R</mml:mi> |
| 325 | </mml:msub> |
| 326 | </mml:mrow> |
| 327 | </mml:mrow> |
| 328 | </mml:math></informalequation> |
| 329 | <informalequation><mml:math> |
| 330 | <!-- eqn: Gr = G sub s s sub G - G sub d d sub G : --> |
| 331 | <mml:mrow> |
| 332 | <mml:mi mathvariant="italic">Gr</mml:mi> |
| 333 | <mml:mo>=</mml:mo> |
| 334 | <mml:mrow> |
| 335 | <mml:msub><mml:mi mathvariant="italic">G</mml:mi> |
| 336 | <mml:mi mathvariant="italic">s</mml:mi> |
| 337 | </mml:msub> |
| 338 | <mml:mo>⁢</mml:mo> |
| 339 | <mml:msub><mml:mi mathvariant="italic">s</mml:mi> |
| 340 | <mml:mi mathvariant="italic">G</mml:mi> |
| 341 | </mml:msub> |
| 342 | <mml:mo>-</mml:mo> |
| 343 | <mml:msub><mml:mi mathvariant="italic">G</mml:mi> |
| 344 | <mml:mi mathvariant="italic">d</mml:mi> |
| 345 | </mml:msub> |
| 346 | <mml:mo>⁢</mml:mo> |
| 347 | <mml:msub><mml:mi mathvariant="italic">d</mml:mi> |
| 348 | <mml:mi mathvariant="italic">G</mml:mi> |
| 349 | </mml:msub> |
| 350 | </mml:mrow> |
| 351 | </mml:mrow> |
| 352 | </mml:math></informalequation> |
| 353 | <informalequation><mml:math> |
| 354 | <!-- eqn: Br = B sub s s sub B - B sub d d sub B : --> |
| 355 | <mml:mrow> |
| 356 | <mml:mi mathvariant="italic">Br</mml:mi> |
| 357 | <mml:mo>=</mml:mo> |
| 358 | <mml:mrow> |
| 359 | <mml:msub><mml:mi mathvariant="italic">B</mml:mi> |
| 360 | <mml:mi mathvariant="italic">s</mml:mi> |
| 361 | </mml:msub> |
| 362 | <mml:mo>⁢</mml:mo> |
| 363 | <mml:msub><mml:mi mathvariant="italic">s</mml:mi> |
| 364 | <mml:mi mathvariant="italic">B</mml:mi> |
| 365 | </mml:msub> |
| 366 | <mml:mo>-</mml:mo> |
| 367 | <mml:msub><mml:mi mathvariant="italic">B</mml:mi> |
| 368 | <mml:mi mathvariant="italic">d</mml:mi> |
| 369 | </mml:msub> |
| 370 | <mml:mo>⁢</mml:mo> |
| 371 | <mml:msub><mml:mi mathvariant="italic">d</mml:mi> |
| 372 | <mml:mi mathvariant="italic">B</mml:mi> |
| 373 | </mml:msub> |
| 374 | </mml:mrow> |
| 375 | </mml:mrow> |
| 376 | </mml:math></informalequation> |
| 377 | </entry> |
| 378 | <entry align="left"> |
| 379 | <informalequation><mml:math> |
| 380 | <!-- eqn: Ar = A sub s s sub A - A sub d d sub A : --> |
| 381 | <mml:mrow> |
| 382 | <mml:mi mathvariant="italic">Ar</mml:mi> |
| 383 | <mml:mo>=</mml:mo> |
| 384 | <mml:mrow> |
| 385 | <mml:msub><mml:mi mathvariant="italic">A</mml:mi> |
| 386 | <mml:mi mathvariant="italic">s</mml:mi> |
| 387 | </mml:msub> |
| 388 | <mml:mo>⁢</mml:mo> |
| 389 | <mml:msub><mml:mi mathvariant="italic">s</mml:mi> |
| 390 | <mml:mi mathvariant="italic">A</mml:mi> |
| 391 | </mml:msub> |
| 392 | <mml:mo>-</mml:mo> |
| 393 | <mml:msub><mml:mi mathvariant="italic">A</mml:mi> |
| 394 | <mml:mi mathvariant="italic">d</mml:mi> |
| 395 | </mml:msub> |
| 396 | <mml:mo>⁢</mml:mo> |
| 397 | <mml:msub><mml:mi mathvariant="italic">d</mml:mi> |
| 398 | <mml:mi mathvariant="italic">A</mml:mi> |
| 399 | </mml:msub> |
| 400 | </mml:mrow> |
| 401 | </mml:mrow> |
| 402 | </mml:math></informalequation> |
| 403 | </entry> |
| 404 | </row> |
| 405 | <row> |
| 406 | <entry align="left"> |
| 407 | <constant>GL_FUNC_REVERSE_SUBTRACT</constant> |
| 408 | </entry> |
| 409 | <entry align="left"> |
| 410 | <informalequation><mml:math> |
| 411 | <!-- eqn: Rr = R sub d d sub R - R sub s s sub R : --> |
| 412 | <mml:mrow> |
| 413 | <mml:mi mathvariant="italic">Rr</mml:mi> |
| 414 | <mml:mo>=</mml:mo> |
| 415 | <mml:mrow> |
| 416 | <mml:msub><mml:mi mathvariant="italic">R</mml:mi> |
| 417 | <mml:mi mathvariant="italic">d</mml:mi> |
| 418 | </mml:msub> |
| 419 | <mml:mo>⁢</mml:mo> |
| 420 | <mml:msub><mml:mi mathvariant="italic">d</mml:mi> |
| 421 | <mml:mi mathvariant="italic">R</mml:mi> |
| 422 | </mml:msub> |
| 423 | <mml:mo>-</mml:mo> |
| 424 | <mml:msub><mml:mi mathvariant="italic">R</mml:mi> |
| 425 | <mml:mi mathvariant="italic">s</mml:mi> |
| 426 | </mml:msub> |
| 427 | <mml:mo>⁢</mml:mo> |
| 428 | <mml:msub><mml:mi mathvariant="italic">s</mml:mi> |
| 429 | <mml:mi mathvariant="italic">R</mml:mi> |
| 430 | </mml:msub> |
| 431 | </mml:mrow> |
| 432 | </mml:mrow> |
| 433 | </mml:math></informalequation> |
| 434 | <informalequation><mml:math> |
| 435 | <!-- eqn: Gr = G sub d d sub G - G sub s s sub G : --> |
| 436 | <mml:mrow> |
| 437 | <mml:mi mathvariant="italic">Gr</mml:mi> |
| 438 | <mml:mo>=</mml:mo> |
| 439 | <mml:mrow> |
| 440 | <mml:msub><mml:mi mathvariant="italic">G</mml:mi> |
| 441 | <mml:mi mathvariant="italic">d</mml:mi> |
| 442 | </mml:msub> |
| 443 | <mml:mo>⁢</mml:mo> |
| 444 | <mml:msub><mml:mi mathvariant="italic">d</mml:mi> |
| 445 | <mml:mi mathvariant="italic">G</mml:mi> |
| 446 | </mml:msub> |
| 447 | <mml:mo>-</mml:mo> |
| 448 | <mml:msub><mml:mi mathvariant="italic">G</mml:mi> |
| 449 | <mml:mi mathvariant="italic">s</mml:mi> |
| 450 | </mml:msub> |
| 451 | <mml:mo>⁢</mml:mo> |
| 452 | <mml:msub><mml:mi mathvariant="italic">s</mml:mi> |
| 453 | <mml:mi mathvariant="italic">G</mml:mi> |
| 454 | </mml:msub> |
| 455 | </mml:mrow> |
| 456 | </mml:mrow> |
| 457 | </mml:math></informalequation> |
| 458 | <informalequation><mml:math> |
| 459 | <!-- eqn: Br = B sub d d sub B - B sub s s sub B : --> |
| 460 | <mml:mrow> |
| 461 | <mml:mi mathvariant="italic">Br</mml:mi> |
| 462 | <mml:mo>=</mml:mo> |
| 463 | <mml:mrow> |
| 464 | <mml:msub><mml:mi mathvariant="italic">B</mml:mi> |
| 465 | <mml:mi mathvariant="italic">d</mml:mi> |
| 466 | </mml:msub> |
| 467 | <mml:mo>⁢</mml:mo> |
| 468 | <mml:msub><mml:mi mathvariant="italic">d</mml:mi> |
| 469 | <mml:mi mathvariant="italic">B</mml:mi> |
| 470 | </mml:msub> |
| 471 | <mml:mo>-</mml:mo> |
| 472 | <mml:msub><mml:mi mathvariant="italic">B</mml:mi> |
| 473 | <mml:mi mathvariant="italic">s</mml:mi> |
| 474 | </mml:msub> |
| 475 | <mml:mo>⁢</mml:mo> |
| 476 | <mml:msub><mml:mi mathvariant="italic">s</mml:mi> |
| 477 | <mml:mi mathvariant="italic">B</mml:mi> |
| 478 | </mml:msub> |
| 479 | </mml:mrow> |
| 480 | </mml:mrow> |
| 481 | </mml:math></informalequation> |
| 482 | </entry> |
| 483 | <entry align="left"> |
| 484 | <informalequation><mml:math> |
| 485 | <!-- eqn: Ar = A sub d d sub A - A sub s s sub A : --> |
| 486 | <mml:mrow> |
| 487 | <mml:mi mathvariant="italic">Ar</mml:mi> |
| 488 | <mml:mo>=</mml:mo> |
| 489 | <mml:mrow> |
| 490 | <mml:msub><mml:mi mathvariant="italic">A</mml:mi> |
| 491 | <mml:mi mathvariant="italic">d</mml:mi> |
| 492 | </mml:msub> |
| 493 | <mml:mo>⁢</mml:mo> |
| 494 | <mml:msub><mml:mi mathvariant="italic">d</mml:mi> |
| 495 | <mml:mi mathvariant="italic">A</mml:mi> |
| 496 | </mml:msub> |
| 497 | <mml:mo>-</mml:mo> |
| 498 | <mml:msub><mml:mi mathvariant="italic">A</mml:mi> |
| 499 | <mml:mi mathvariant="italic">s</mml:mi> |
| 500 | </mml:msub> |
| 501 | <mml:mo>⁢</mml:mo> |
| 502 | <mml:msub><mml:mi mathvariant="italic">s</mml:mi> |
| 503 | <mml:mi mathvariant="italic">A</mml:mi> |
| 504 | </mml:msub> |
| 505 | </mml:mrow> |
| 506 | </mml:mrow> |
| 507 | </mml:math></informalequation> |
| 508 | </entry> |
| 509 | </row> |
| 510 | <row> |
| 511 | <entry align="left"> |
| 512 | <constant>GL_MIN</constant> |
| 513 | </entry> |
| 514 | <entry align="left"> |
| 515 | <informalequation><mml:math> |
| 516 | <!-- eqn: Rr = min ( R sub s, R sub d): --> |
| 517 | <mml:mrow> |
| 518 | <mml:mi mathvariant="italic">Rr</mml:mi> |
| 519 | <mml:mo>=</mml:mo> |
| 520 | <mml:mrow> |
| 521 | <mml:mi mathvariant="italic">min</mml:mi> |
| 522 | <mml:mo>⁡</mml:mo> |
| 523 | <mml:mfenced open="(" close=")"> |
| 524 | <mml:mrow> |
| 525 | <mml:msub><mml:mi mathvariant="italic">R</mml:mi> |
| 526 | <mml:mi mathvariant="italic">s</mml:mi> |
| 527 | </mml:msub> |
| 528 | </mml:mrow> |
| 529 | <mml:mrow> |
| 530 | <mml:msub><mml:mi mathvariant="italic">R</mml:mi> |
| 531 | <mml:mi mathvariant="italic">d</mml:mi> |
| 532 | </mml:msub> |
| 533 | </mml:mrow> |
| 534 | </mml:mfenced> |
| 535 | </mml:mrow> |
| 536 | </mml:mrow> |
| 537 | </mml:math></informalequation> |
| 538 | <informalequation><mml:math> |
| 539 | <!-- eqn: Gr = min ( G sub s, G sub d): --> |
| 540 | <mml:mrow> |
| 541 | <mml:mi mathvariant="italic">Gr</mml:mi> |
| 542 | <mml:mo>=</mml:mo> |
| 543 | <mml:mrow> |
| 544 | <mml:mi mathvariant="italic">min</mml:mi> |
| 545 | <mml:mo>⁡</mml:mo> |
| 546 | <mml:mfenced open="(" close=")"> |
| 547 | <mml:mrow> |
| 548 | <mml:msub><mml:mi mathvariant="italic">G</mml:mi> |
| 549 | <mml:mi mathvariant="italic">s</mml:mi> |
| 550 | </mml:msub> |
| 551 | </mml:mrow> |
| 552 | <mml:mrow> |
| 553 | <mml:msub><mml:mi mathvariant="italic">G</mml:mi> |
| 554 | <mml:mi mathvariant="italic">d</mml:mi> |
| 555 | </mml:msub> |
| 556 | </mml:mrow> |
| 557 | </mml:mfenced> |
| 558 | </mml:mrow> |
| 559 | </mml:mrow> |
| 560 | </mml:math></informalequation> |
| 561 | <informalequation><mml:math> |
| 562 | <!-- eqn: Br = min ( B sub s, B sub d): --> |
| 563 | <mml:mrow> |
| 564 | <mml:mi mathvariant="italic">Br</mml:mi> |
| 565 | <mml:mo>=</mml:mo> |
| 566 | <mml:mrow> |
| 567 | <mml:mi mathvariant="italic">min</mml:mi> |
| 568 | <mml:mo>⁡</mml:mo> |
| 569 | <mml:mfenced open="(" close=")"> |
| 570 | <mml:mrow> |
| 571 | <mml:msub><mml:mi mathvariant="italic">B</mml:mi> |
| 572 | <mml:mi mathvariant="italic">s</mml:mi> |
| 573 | </mml:msub> |
| 574 | </mml:mrow> |
| 575 | <mml:mrow> |
| 576 | <mml:msub><mml:mi mathvariant="italic">B</mml:mi> |
| 577 | <mml:mi mathvariant="italic">d</mml:mi> |
| 578 | </mml:msub> |
| 579 | </mml:mrow> |
| 580 | </mml:mfenced> |
| 581 | </mml:mrow> |
| 582 | </mml:mrow> |
| 583 | </mml:math></informalequation> |
| 584 | </entry> |
| 585 | <entry align="left"> |
| 586 | <informalequation><mml:math> |
| 587 | <!-- eqn: Ar = min ( A sub s, A sub d): --> |
| 588 | <mml:mrow> |
| 589 | <mml:mi mathvariant="italic">Ar</mml:mi> |
| 590 | <mml:mo>=</mml:mo> |
| 591 | <mml:mrow> |
| 592 | <mml:mi mathvariant="italic">min</mml:mi> |
| 593 | <mml:mo>⁡</mml:mo> |
| 594 | <mml:mfenced open="(" close=")"> |
| 595 | <mml:mrow> |
| 596 | <mml:msub><mml:mi mathvariant="italic">A</mml:mi> |
| 597 | <mml:mi mathvariant="italic">s</mml:mi> |
| 598 | </mml:msub> |
| 599 | </mml:mrow> |
| 600 | <mml:mrow> |
| 601 | <mml:msub><mml:mi mathvariant="italic">A</mml:mi> |
| 602 | <mml:mi mathvariant="italic">d</mml:mi> |
| 603 | </mml:msub> |
| 604 | </mml:mrow> |
| 605 | </mml:mfenced> |
| 606 | </mml:mrow> |
| 607 | </mml:mrow> |
| 608 | </mml:math></informalequation> |
| 609 | </entry> |
| 610 | </row> |
| 611 | <row> |
| 612 | <entry align="left"> |
| 613 | <constant>GL_MAX</constant> |
| 614 | </entry> |
| 615 | <entry align="left"> |
| 616 | <informalequation><mml:math> |
| 617 | <!-- eqn: Rr = max ( R sub s, R sub d): --> |
| 618 | <mml:mrow> |
| 619 | <mml:mi mathvariant="italic">Rr</mml:mi> |
| 620 | <mml:mo>=</mml:mo> |
| 621 | <mml:mrow> |
| 622 | <mml:mi mathvariant="italic">max</mml:mi> |
| 623 | <mml:mo>⁡</mml:mo> |
| 624 | <mml:mfenced open="(" close=")"> |
| 625 | <mml:mrow> |
| 626 | <mml:msub><mml:mi mathvariant="italic">R</mml:mi> |
| 627 | <mml:mi mathvariant="italic">s</mml:mi> |
| 628 | </mml:msub> |
| 629 | </mml:mrow> |
| 630 | <mml:mrow> |
| 631 | <mml:msub><mml:mi mathvariant="italic">R</mml:mi> |
| 632 | <mml:mi mathvariant="italic">d</mml:mi> |
| 633 | </mml:msub> |
| 634 | </mml:mrow> |
| 635 | </mml:mfenced> |
| 636 | </mml:mrow> |
| 637 | </mml:mrow> |
| 638 | </mml:math></informalequation> |
| 639 | <informalequation><mml:math> |
| 640 | <!-- eqn: Gr = max ( G sub s, G sub d): --> |
| 641 | <mml:mrow> |
| 642 | <mml:mi mathvariant="italic">Gr</mml:mi> |
| 643 | <mml:mo>=</mml:mo> |
| 644 | <mml:mrow> |
| 645 | <mml:mi mathvariant="italic">max</mml:mi> |
| 646 | <mml:mo>⁡</mml:mo> |
| 647 | <mml:mfenced open="(" close=")"> |
| 648 | <mml:mrow> |
| 649 | <mml:msub><mml:mi mathvariant="italic">G</mml:mi> |
| 650 | <mml:mi mathvariant="italic">s</mml:mi> |
| 651 | </mml:msub> |
| 652 | </mml:mrow> |
| 653 | <mml:mrow> |
| 654 | <mml:msub><mml:mi mathvariant="italic">G</mml:mi> |
| 655 | <mml:mi mathvariant="italic">d</mml:mi> |
| 656 | </mml:msub> |
| 657 | </mml:mrow> |
| 658 | </mml:mfenced> |
| 659 | </mml:mrow> |
| 660 | </mml:mrow> |
| 661 | </mml:math></informalequation> |
| 662 | <informalequation><mml:math> |
| 663 | <!-- eqn: Br = max ( B sub s, B sub d): --> |
| 664 | <mml:mrow> |
| 665 | <mml:mi mathvariant="italic">Br</mml:mi> |
| 666 | <mml:mo>=</mml:mo> |
| 667 | <mml:mrow> |
| 668 | <mml:mi mathvariant="italic">max</mml:mi> |
| 669 | <mml:mo>⁡</mml:mo> |
| 670 | <mml:mfenced open="(" close=")"> |
| 671 | <mml:mrow> |
| 672 | <mml:msub><mml:mi mathvariant="italic">B</mml:mi> |
| 673 | <mml:mi mathvariant="italic">s</mml:mi> |
| 674 | </mml:msub> |
| 675 | </mml:mrow> |
| 676 | <mml:mrow> |
| 677 | <mml:msub><mml:mi mathvariant="italic">B</mml:mi> |
| 678 | <mml:mi mathvariant="italic">d</mml:mi> |
| 679 | </mml:msub> |
| 680 | </mml:mrow> |
| 681 | </mml:mfenced> |
| 682 | </mml:mrow> |
| 683 | </mml:mrow> |
| 684 | </mml:math></informalequation> |
| 685 | </entry> |
| 686 | <entry align="left"> |
| 687 | <informalequation><mml:math> |
| 688 | <!-- eqn: Ar = max ( A sub s, A sub d): --> |
| 689 | <mml:mrow> |
| 690 | <mml:mi mathvariant="italic">Ar</mml:mi> |
| 691 | <mml:mo>=</mml:mo> |
| 692 | <mml:mrow> |
| 693 | <mml:mi mathvariant="italic">max</mml:mi> |
| 694 | <mml:mo>⁡</mml:mo> |
| 695 | <mml:mfenced open="(" close=")"> |
| 696 | <mml:mrow> |
| 697 | <mml:msub><mml:mi mathvariant="italic">A</mml:mi> |
| 698 | <mml:mi mathvariant="italic">s</mml:mi> |
| 699 | </mml:msub> |
| 700 | </mml:mrow> |
| 701 | <mml:mrow> |
| 702 | <mml:msub><mml:mi mathvariant="italic">A</mml:mi> |
| 703 | <mml:mi mathvariant="italic">d</mml:mi> |
| 704 | </mml:msub> |
| 705 | </mml:mrow> |
| 706 | </mml:mfenced> |
| 707 | </mml:mrow> |
| 708 | </mml:mrow> |
| 709 | </mml:math></informalequation> |
| 710 | </entry> |
| 711 | </row> |
| 712 | </tbody> |
| 713 | </tgroup> |
| 714 | </informaltable> |
| 715 | </para> |
| 716 | <para> |
| 717 | The results of these equations are clamped to the range |
| 718 | <inlineequation><mml:math> |
| 719 | <!-- eqn: [0,1]: --> |
| 720 | <mml:mfenced open="[" close="]"> |
| 721 | <mml:mn>0</mml:mn> |
| 722 | <mml:mn>1</mml:mn> |
| 723 | </mml:mfenced> |
| 724 | </mml:math></inlineequation>. |
| 725 | </para> |
| 726 | <para> |
| 727 | The <constant>GL_MIN</constant> and <constant>GL_MAX</constant> equations are useful for applications |
| 728 | that analyze image data (image thresholding against a constant color, |
| 729 | for example). |
| 730 | The <constant>GL_FUNC_ADD</constant> equation is useful |
| 731 | for antialiasing and transparency, among other things. |
| 732 | </para> |
| 733 | <para> |
| 734 | Initially, both the RGB blend equation and the alpha blend equation are set to <constant>GL_FUNC_ADD</constant>. |
| 735 | </para> |
| 736 | <para> |
| 737 | </para> |
| 738 | </refsect1> |
| 739 | <refsect1 id="notes"><title>Notes</title> |
| 740 | <para> |
| 741 | The <constant>GL_MIN</constant>, and <constant>GL_MAX</constant> equations do not use |
| 742 | the source or destination factors, only the source and destination colors. |
| 743 | </para> |
| 744 | </refsect1> |
| 745 | <refsect1 id="errors"><title>Errors</title> |
| 746 | <para> |
| 747 | <constant>GL_INVALID_ENUM</constant> is generated if <parameter>mode</parameter> is not one of |
| 748 | <constant>GL_FUNC_ADD</constant>, <constant>GL_FUNC_SUBTRACT</constant>, <constant>GL_FUNC_REVERSE_SUBTRACT</constant>, |
| 749 | <constant>GL_MAX</constant>, or <constant>GL_MIN</constant>. |
| 750 | </para> |
| 751 | <para> |
| 752 | <constant>GL_INVALID_VALUE</constant> is generated by <function>glBlendEquationi</function> if <parameter>buf</parameter> is greater |
| 753 | than or equal to the value of <constant>GL_MAX_DRAW_BUFFERS</constant>. |
| 754 | </para> |
| 755 | </refsect1> |
| 756 | <refsect1 id="associatedgets"><title>Associated Gets</title> |
| 757 | <para> |
| 758 | <citerefentry><refentrytitle>glGet</refentrytitle></citerefentry> with an argument of <constant>GL_BLEND_EQUATION_RGB</constant> |
| 759 | </para> |
| 760 | <para> |
| 761 | <citerefentry><refentrytitle>glGet</refentrytitle></citerefentry> with an argument of <constant>GL_BLEND_EQUATION_ALPHA</constant> |
| 762 | </para> |
| 763 | </refsect1> |
| 764 | <refsect1 id="seealso"><title>See Also</title> |
| 765 | <para> |
| 766 | <citerefentry><refentrytitle>glBlendColor</refentrytitle></citerefentry>, |
| 767 | <citerefentry><refentrytitle>glBlendFunc</refentrytitle></citerefentry> |
| 768 | <citerefentry><refentrytitle>glBlendFuncSeparate</refentrytitle></citerefentry> |
| 769 | </para> |
| 770 | </refsect1> |
| 771 | <refsect1 id="Copyright"><title>Copyright</title> |
| 772 | <para> |
| 773 | Copyright <trademark class="copyright"></trademark> 1991-2006 |
| 774 | Silicon Graphics, Inc. This document is licensed under the SGI |
| 775 | Free Software B License. For details, see |
| 776 | <ulink url="http://oss.sgi.com/projects/FreeB/">http://oss.sgi.com/projects/FreeB/</ulink>. |
| 777 | </para> |
| 778 | </refsect1> |
| 779 | </refentry> |