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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> |