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">
9 <holder>Silicon Graphics, Inc.
</holder>
12 <refentrytitle>glBlendEquation
</refentrytitle>
13 <manvolnum>3G
</manvolnum>
16 <refname>glBlendEquation
</refname>
17 <refpurpose>specify the equation used for both the RGB blend equation and the Alpha blend equation
</refpurpose>
19 <refsynopsisdiv><title>C Specification
</title>
22 <funcdef>void
<function>glBlendEquation
</function></funcdef>
23 <paramdef>GLenum
<parameter>mode
</parameter></paramdef>
26 <funcdef>void
<function>glBlendEquationi
</function></funcdef>
27 <paramdef>GLuint
<parameter>buf
</parameter></paramdef>
28 <paramdef>GLenum
<parameter>mode
</parameter></paramdef>
32 <!-- eqn: ignoring delim $$ -->
33 <refsect1 id=
"parameters"><title>Parameters
</title>
36 <term><parameter>buf
</parameter></term>
39 for
<function>glBlendEquationi
</function>, specifies the index of the draw buffer
40 for which to set the blend equation.
45 <term><parameter>mode
</parameter></term>
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>.
56 <refsect1 id=
"description"><title>Description
</title>
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.
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.
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>
81 <mml:msub><mml:mi mathvariant=
"italic">G
</mml:mi>
82 <mml:mi mathvariant=
"italic">s
</mml:mi>
84 <mml:msub><mml:mi mathvariant=
"italic">B
</mml:mi>
85 <mml:mi mathvariant=
"italic">s
</mml:mi>
87 <mml:msub><mml:mi mathvariant=
"italic">A
</mml:mi>
88 <mml:mi mathvariant=
"italic">s
</mml:mi>
91 </mml:math></inlineequation>
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>
99 <mml:msub><mml:mi mathvariant=
"italic">G
</mml:mi>
100 <mml:mi mathvariant=
"italic">d
</mml:mi>
102 <mml:msub><mml:mi mathvariant=
"italic">B
</mml:mi>
103 <mml:mi mathvariant=
"italic">d
</mml:mi>
105 <mml:msub><mml:mi mathvariant=
"italic">A
</mml:mi>
106 <mml:mi mathvariant=
"italic">d
</mml:mi>
109 </mml:math></inlineequation>,
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>
118 <mml:msub><mml:mi mathvariant=
"italic">G
</mml:mi>
119 <mml:mi mathvariant=
"italic">r
</mml:mi>
121 <mml:msub><mml:mi mathvariant=
"italic">B
</mml:mi>
122 <mml:mi mathvariant=
"italic">r
</mml:mi>
124 <mml:msub><mml:mi mathvariant=
"italic">A
</mml:mi>
125 <mml:mi mathvariant=
"italic">r
</mml:mi>
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>
136 <mml:msub><mml:mi mathvariant=
"italic">s
</mml:mi>
137 <mml:mi mathvariant=
"italic">G
</mml:mi>
139 <mml:msub><mml:mi mathvariant=
"italic">s
</mml:mi>
140 <mml:mi mathvariant=
"italic">B
</mml:mi>
142 <mml:msub><mml:mi mathvariant=
"italic">s
</mml:mi>
143 <mml:mi mathvariant=
"italic">A
</mml:mi>
146 </mml:math></inlineequation>
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>
154 <mml:msub><mml:mi mathvariant=
"italic">d
</mml:mi>
155 <mml:mi mathvariant=
"italic">G
</mml:mi>
157 <mml:msub><mml:mi mathvariant=
"italic">d
</mml:mi>
158 <mml:mi mathvariant=
"italic">B
</mml:mi>
160 <mml:msub><mml:mi mathvariant=
"italic">d
</mml:mi>
161 <mml:mi mathvariant=
"italic">A
</mml:mi>
164 </mml:math></inlineequation>,
166 For these equations all color components are understood to have values
168 <inlineequation><mml:math>
170 <mml:mfenced open=
"[" close=
"]">
174 </mml:math></inlineequation>.
176 <informaltable frame=
"topbot">
177 <tgroup cols=
"3" align=
"left">
178 <colspec colwidth=
"1.1*" />
179 <colspec colwidth=
"1*" />
180 <colspec colwidth=
"1*" />
183 <entry rowsep=
"1" align=
"left"><emphasis role=
"bold">
186 <entry rowsep=
"1" align=
"left"><emphasis role=
"bold">
189 <entry rowsep=
"1" align=
"left"><emphasis role=
"bold">
197 <constant>GL_FUNC_ADD
</constant>
200 <informalequation><mml:math>
201 <!-- eqn: Rr = R sub s s sub R + R sub d d sub R : -->
203 <mml:mi mathvariant=
"italic">Rr
</mml:mi>
206 <mml:msub><mml:mi mathvariant=
"italic">R
</mml:mi>
207 <mml:mi mathvariant=
"italic">s
</mml:mi>
209 <mml:mo>⁢</mml:mo>
210 <mml:msub><mml:mi mathvariant=
"italic">s
</mml:mi>
211 <mml:mi mathvariant=
"italic">R
</mml:mi>
214 <mml:msub><mml:mi mathvariant=
"italic">R
</mml:mi>
215 <mml:mi mathvariant=
"italic">d
</mml:mi>
217 <mml:mo>⁢</mml:mo>
218 <mml:msub><mml:mi mathvariant=
"italic">d
</mml:mi>
219 <mml:mi mathvariant=
"italic">R
</mml:mi>
223 </mml:math></informalequation>
224 <informalequation><mml:math>
225 <!-- eqn: Gr = G sub s s sub G + G sub d d sub G : -->
227 <mml:mi mathvariant=
"italic">Gr
</mml:mi>
230 <mml:msub><mml:mi mathvariant=
"italic">G
</mml:mi>
231 <mml:mi mathvariant=
"italic">s
</mml:mi>
233 <mml:mo>⁢</mml:mo>
234 <mml:msub><mml:mi mathvariant=
"italic">s
</mml:mi>
235 <mml:mi mathvariant=
"italic">G
</mml:mi>
238 <mml:msub><mml:mi mathvariant=
"italic">G
</mml:mi>
239 <mml:mi mathvariant=
"italic">d
</mml:mi>
241 <mml:mo>⁢</mml:mo>
242 <mml:msub><mml:mi mathvariant=
"italic">d
</mml:mi>
243 <mml:mi mathvariant=
"italic">G
</mml:mi>
247 </mml:math></informalequation>
248 <informalequation><mml:math>
249 <!-- eqn: Br = B sub s s sub B + B sub d d sub B : -->
251 <mml:mi mathvariant=
"italic">Br
</mml:mi>
254 <mml:msub><mml:mi mathvariant=
"italic">B
</mml:mi>
255 <mml:mi mathvariant=
"italic">s
</mml:mi>
257 <mml:mo>⁢</mml:mo>
258 <mml:msub><mml:mi mathvariant=
"italic">s
</mml:mi>
259 <mml:mi mathvariant=
"italic">B
</mml:mi>
262 <mml:msub><mml:mi mathvariant=
"italic">B
</mml:mi>
263 <mml:mi mathvariant=
"italic">d
</mml:mi>
265 <mml:mo>⁢</mml:mo>
266 <mml:msub><mml:mi mathvariant=
"italic">d
</mml:mi>
267 <mml:mi mathvariant=
"italic">B
</mml:mi>
271 </mml:math></informalequation>
274 <informalequation><mml:math>
275 <!-- eqn: Ar = A sub s s sub A + A sub d d sub A : -->
277 <mml:mi mathvariant=
"italic">Ar
</mml:mi>
280 <mml:msub><mml:mi mathvariant=
"italic">A
</mml:mi>
281 <mml:mi mathvariant=
"italic">s
</mml:mi>
283 <mml:mo>⁢</mml:mo>
284 <mml:msub><mml:mi mathvariant=
"italic">s
</mml:mi>
285 <mml:mi mathvariant=
"italic">A
</mml:mi>
288 <mml:msub><mml:mi mathvariant=
"italic">A
</mml:mi>
289 <mml:mi mathvariant=
"italic">d
</mml:mi>
291 <mml:mo>⁢</mml:mo>
292 <mml:msub><mml:mi mathvariant=
"italic">d
</mml:mi>
293 <mml:mi mathvariant=
"italic">A
</mml:mi>
297 </mml:math></informalequation>
302 <constant>GL_FUNC_SUBTRACT
</constant>
305 <informalequation><mml:math>
306 <!-- eqn: Rr = R sub s s sub R - R sub d d sub R : -->
308 <mml:mi mathvariant=
"italic">Rr
</mml:mi>
311 <mml:msub><mml:mi mathvariant=
"italic">R
</mml:mi>
312 <mml:mi mathvariant=
"italic">s
</mml:mi>
314 <mml:mo>⁢</mml:mo>
315 <mml:msub><mml:mi mathvariant=
"italic">s
</mml:mi>
316 <mml:mi mathvariant=
"italic">R
</mml:mi>
319 <mml:msub><mml:mi mathvariant=
"italic">R
</mml:mi>
320 <mml:mi mathvariant=
"italic">d
</mml:mi>
322 <mml:mo>⁢</mml:mo>
323 <mml:msub><mml:mi mathvariant=
"italic">d
</mml:mi>
324 <mml:mi mathvariant=
"italic">R
</mml:mi>
328 </mml:math></informalequation>
329 <informalequation><mml:math>
330 <!-- eqn: Gr = G sub s s sub G - G sub d d sub G : -->
332 <mml:mi mathvariant=
"italic">Gr
</mml:mi>
335 <mml:msub><mml:mi mathvariant=
"italic">G
</mml:mi>
336 <mml:mi mathvariant=
"italic">s
</mml:mi>
338 <mml:mo>⁢</mml:mo>
339 <mml:msub><mml:mi mathvariant=
"italic">s
</mml:mi>
340 <mml:mi mathvariant=
"italic">G
</mml:mi>
343 <mml:msub><mml:mi mathvariant=
"italic">G
</mml:mi>
344 <mml:mi mathvariant=
"italic">d
</mml:mi>
346 <mml:mo>⁢</mml:mo>
347 <mml:msub><mml:mi mathvariant=
"italic">d
</mml:mi>
348 <mml:mi mathvariant=
"italic">G
</mml:mi>
352 </mml:math></informalequation>
353 <informalequation><mml:math>
354 <!-- eqn: Br = B sub s s sub B - B sub d d sub B : -->
356 <mml:mi mathvariant=
"italic">Br
</mml:mi>
359 <mml:msub><mml:mi mathvariant=
"italic">B
</mml:mi>
360 <mml:mi mathvariant=
"italic">s
</mml:mi>
362 <mml:mo>⁢</mml:mo>
363 <mml:msub><mml:mi mathvariant=
"italic">s
</mml:mi>
364 <mml:mi mathvariant=
"italic">B
</mml:mi>
367 <mml:msub><mml:mi mathvariant=
"italic">B
</mml:mi>
368 <mml:mi mathvariant=
"italic">d
</mml:mi>
370 <mml:mo>⁢</mml:mo>
371 <mml:msub><mml:mi mathvariant=
"italic">d
</mml:mi>
372 <mml:mi mathvariant=
"italic">B
</mml:mi>
376 </mml:math></informalequation>
379 <informalequation><mml:math>
380 <!-- eqn: Ar = A sub s s sub A - A sub d d sub A : -->
382 <mml:mi mathvariant=
"italic">Ar
</mml:mi>
385 <mml:msub><mml:mi mathvariant=
"italic">A
</mml:mi>
386 <mml:mi mathvariant=
"italic">s
</mml:mi>
388 <mml:mo>⁢</mml:mo>
389 <mml:msub><mml:mi mathvariant=
"italic">s
</mml:mi>
390 <mml:mi mathvariant=
"italic">A
</mml:mi>
393 <mml:msub><mml:mi mathvariant=
"italic">A
</mml:mi>
394 <mml:mi mathvariant=
"italic">d
</mml:mi>
396 <mml:mo>⁢</mml:mo>
397 <mml:msub><mml:mi mathvariant=
"italic">d
</mml:mi>
398 <mml:mi mathvariant=
"italic">A
</mml:mi>
402 </mml:math></informalequation>
407 <constant>GL_FUNC_REVERSE_SUBTRACT
</constant>
410 <informalequation><mml:math>
411 <!-- eqn: Rr = R sub d d sub R - R sub s s sub R : -->
413 <mml:mi mathvariant=
"italic">Rr
</mml:mi>
416 <mml:msub><mml:mi mathvariant=
"italic">R
</mml:mi>
417 <mml:mi mathvariant=
"italic">d
</mml:mi>
419 <mml:mo>⁢</mml:mo>
420 <mml:msub><mml:mi mathvariant=
"italic">d
</mml:mi>
421 <mml:mi mathvariant=
"italic">R
</mml:mi>
424 <mml:msub><mml:mi mathvariant=
"italic">R
</mml:mi>
425 <mml:mi mathvariant=
"italic">s
</mml:mi>
427 <mml:mo>⁢</mml:mo>
428 <mml:msub><mml:mi mathvariant=
"italic">s
</mml:mi>
429 <mml:mi mathvariant=
"italic">R
</mml:mi>
433 </mml:math></informalequation>
434 <informalequation><mml:math>
435 <!-- eqn: Gr = G sub d d sub G - G sub s s sub G : -->
437 <mml:mi mathvariant=
"italic">Gr
</mml:mi>
440 <mml:msub><mml:mi mathvariant=
"italic">G
</mml:mi>
441 <mml:mi mathvariant=
"italic">d
</mml:mi>
443 <mml:mo>⁢</mml:mo>
444 <mml:msub><mml:mi mathvariant=
"italic">d
</mml:mi>
445 <mml:mi mathvariant=
"italic">G
</mml:mi>
448 <mml:msub><mml:mi mathvariant=
"italic">G
</mml:mi>
449 <mml:mi mathvariant=
"italic">s
</mml:mi>
451 <mml:mo>⁢</mml:mo>
452 <mml:msub><mml:mi mathvariant=
"italic">s
</mml:mi>
453 <mml:mi mathvariant=
"italic">G
</mml:mi>
457 </mml:math></informalequation>
458 <informalequation><mml:math>
459 <!-- eqn: Br = B sub d d sub B - B sub s s sub B : -->
461 <mml:mi mathvariant=
"italic">Br
</mml:mi>
464 <mml:msub><mml:mi mathvariant=
"italic">B
</mml:mi>
465 <mml:mi mathvariant=
"italic">d
</mml:mi>
467 <mml:mo>⁢</mml:mo>
468 <mml:msub><mml:mi mathvariant=
"italic">d
</mml:mi>
469 <mml:mi mathvariant=
"italic">B
</mml:mi>
472 <mml:msub><mml:mi mathvariant=
"italic">B
</mml:mi>
473 <mml:mi mathvariant=
"italic">s
</mml:mi>
475 <mml:mo>⁢</mml:mo>
476 <mml:msub><mml:mi mathvariant=
"italic">s
</mml:mi>
477 <mml:mi mathvariant=
"italic">B
</mml:mi>
481 </mml:math></informalequation>
484 <informalequation><mml:math>
485 <!-- eqn: Ar = A sub d d sub A - A sub s s sub A : -->
487 <mml:mi mathvariant=
"italic">Ar
</mml:mi>
490 <mml:msub><mml:mi mathvariant=
"italic">A
</mml:mi>
491 <mml:mi mathvariant=
"italic">d
</mml:mi>
493 <mml:mo>⁢</mml:mo>
494 <mml:msub><mml:mi mathvariant=
"italic">d
</mml:mi>
495 <mml:mi mathvariant=
"italic">A
</mml:mi>
498 <mml:msub><mml:mi mathvariant=
"italic">A
</mml:mi>
499 <mml:mi mathvariant=
"italic">s
</mml:mi>
501 <mml:mo>⁢</mml:mo>
502 <mml:msub><mml:mi mathvariant=
"italic">s
</mml:mi>
503 <mml:mi mathvariant=
"italic">A
</mml:mi>
507 </mml:math></informalequation>
512 <constant>GL_MIN
</constant>
515 <informalequation><mml:math>
516 <!-- eqn: Rr = min ( R sub s, R sub d): -->
518 <mml:mi mathvariant=
"italic">Rr
</mml:mi>
521 <mml:mi mathvariant=
"italic">min
</mml:mi>
522 <mml:mo>⁡</mml:mo>
523 <mml:mfenced open=
"(" close=
")">
525 <mml:msub><mml:mi mathvariant=
"italic">R
</mml:mi>
526 <mml:mi mathvariant=
"italic">s
</mml:mi>
530 <mml:msub><mml:mi mathvariant=
"italic">R
</mml:mi>
531 <mml:mi mathvariant=
"italic">d
</mml:mi>
537 </mml:math></informalequation>
538 <informalequation><mml:math>
539 <!-- eqn: Gr = min ( G sub s, G sub d): -->
541 <mml:mi mathvariant=
"italic">Gr
</mml:mi>
544 <mml:mi mathvariant=
"italic">min
</mml:mi>
545 <mml:mo>⁡</mml:mo>
546 <mml:mfenced open=
"(" close=
")">
548 <mml:msub><mml:mi mathvariant=
"italic">G
</mml:mi>
549 <mml:mi mathvariant=
"italic">s
</mml:mi>
553 <mml:msub><mml:mi mathvariant=
"italic">G
</mml:mi>
554 <mml:mi mathvariant=
"italic">d
</mml:mi>
560 </mml:math></informalequation>
561 <informalequation><mml:math>
562 <!-- eqn: Br = min ( B sub s, B sub d): -->
564 <mml:mi mathvariant=
"italic">Br
</mml:mi>
567 <mml:mi mathvariant=
"italic">min
</mml:mi>
568 <mml:mo>⁡</mml:mo>
569 <mml:mfenced open=
"(" close=
")">
571 <mml:msub><mml:mi mathvariant=
"italic">B
</mml:mi>
572 <mml:mi mathvariant=
"italic">s
</mml:mi>
576 <mml:msub><mml:mi mathvariant=
"italic">B
</mml:mi>
577 <mml:mi mathvariant=
"italic">d
</mml:mi>
583 </mml:math></informalequation>
586 <informalequation><mml:math>
587 <!-- eqn: Ar = min ( A sub s, A sub d): -->
589 <mml:mi mathvariant=
"italic">Ar
</mml:mi>
592 <mml:mi mathvariant=
"italic">min
</mml:mi>
593 <mml:mo>⁡</mml:mo>
594 <mml:mfenced open=
"(" close=
")">
596 <mml:msub><mml:mi mathvariant=
"italic">A
</mml:mi>
597 <mml:mi mathvariant=
"italic">s
</mml:mi>
601 <mml:msub><mml:mi mathvariant=
"italic">A
</mml:mi>
602 <mml:mi mathvariant=
"italic">d
</mml:mi>
608 </mml:math></informalequation>
613 <constant>GL_MAX
</constant>
616 <informalequation><mml:math>
617 <!-- eqn: Rr = max ( R sub s, R sub d): -->
619 <mml:mi mathvariant=
"italic">Rr
</mml:mi>
622 <mml:mi mathvariant=
"italic">max
</mml:mi>
623 <mml:mo>⁡</mml:mo>
624 <mml:mfenced open=
"(" close=
")">
626 <mml:msub><mml:mi mathvariant=
"italic">R
</mml:mi>
627 <mml:mi mathvariant=
"italic">s
</mml:mi>
631 <mml:msub><mml:mi mathvariant=
"italic">R
</mml:mi>
632 <mml:mi mathvariant=
"italic">d
</mml:mi>
638 </mml:math></informalequation>
639 <informalequation><mml:math>
640 <!-- eqn: Gr = max ( G sub s, G sub d): -->
642 <mml:mi mathvariant=
"italic">Gr
</mml:mi>
645 <mml:mi mathvariant=
"italic">max
</mml:mi>
646 <mml:mo>⁡</mml:mo>
647 <mml:mfenced open=
"(" close=
")">
649 <mml:msub><mml:mi mathvariant=
"italic">G
</mml:mi>
650 <mml:mi mathvariant=
"italic">s
</mml:mi>
654 <mml:msub><mml:mi mathvariant=
"italic">G
</mml:mi>
655 <mml:mi mathvariant=
"italic">d
</mml:mi>
661 </mml:math></informalequation>
662 <informalequation><mml:math>
663 <!-- eqn: Br = max ( B sub s, B sub d): -->
665 <mml:mi mathvariant=
"italic">Br
</mml:mi>
668 <mml:mi mathvariant=
"italic">max
</mml:mi>
669 <mml:mo>⁡</mml:mo>
670 <mml:mfenced open=
"(" close=
")">
672 <mml:msub><mml:mi mathvariant=
"italic">B
</mml:mi>
673 <mml:mi mathvariant=
"italic">s
</mml:mi>
677 <mml:msub><mml:mi mathvariant=
"italic">B
</mml:mi>
678 <mml:mi mathvariant=
"italic">d
</mml:mi>
684 </mml:math></informalequation>
687 <informalequation><mml:math>
688 <!-- eqn: Ar = max ( A sub s, A sub d): -->
690 <mml:mi mathvariant=
"italic">Ar
</mml:mi>
693 <mml:mi mathvariant=
"italic">max
</mml:mi>
694 <mml:mo>⁡</mml:mo>
695 <mml:mfenced open=
"(" close=
")">
697 <mml:msub><mml:mi mathvariant=
"italic">A
</mml:mi>
698 <mml:mi mathvariant=
"italic">s
</mml:mi>
702 <mml:msub><mml:mi mathvariant=
"italic">A
</mml:mi>
703 <mml:mi mathvariant=
"italic">d
</mml:mi>
709 </mml:math></informalequation>
717 The results of these equations are clamped to the range
718 <inlineequation><mml:math>
720 <mml:mfenced open=
"[" close=
"]">
724 </mml:math></inlineequation>.
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,
730 The
<constant>GL_FUNC_ADD
</constant> equation is useful
731 for antialiasing and transparency, among other things.
734 Initially, both the RGB blend equation and the alpha blend equation are set to
<constant>GL_FUNC_ADD
</constant>.
739 <refsect1 id=
"notes"><title>Notes
</title>
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.
745 <refsect1 id=
"errors"><title>Errors
</title>
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>.
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>.
756 <refsect1 id=
"associatedgets"><title>Associated Gets
</title>
758 <citerefentry><refentrytitle>glGet
</refentrytitle></citerefentry> with an argument of
<constant>GL_BLEND_EQUATION_RGB
</constant>
761 <citerefentry><refentrytitle>glGet
</refentrytitle></citerefentry> with an argument of
<constant>GL_BLEND_EQUATION_ALPHA
</constant>
764 <refsect1 id=
"seealso"><title>See Also
</title>
766 <citerefentry><refentrytitle>glBlendColor
</refentrytitle></citerefentry>,
767 <citerefentry><refentrytitle>glBlendFunc
</refentrytitle></citerefentry>
768 <citerefentry><refentrytitle>glBlendFuncSeparate
</refentrytitle></citerefentry>
771 <refsect1 id=
"Copyright"><title>Copyright
</title>
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>.