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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="glBlendEquationSeparate"> | |
5 | <refmeta> | |
6 | <refmetainfo> | |
7 | <copyright> | |
8 | <year>1991-2006</year> | |
9 | <holder>Silicon Graphics, Inc.</holder> | |
10 | </copyright> | |
11 | </refmetainfo> | |
12 | <refentrytitle>glBlendEquationSeparate</refentrytitle> | |
13 | <manvolnum>3G</manvolnum> | |
14 | </refmeta> | |
15 | <refnamediv> | |
16 | <refname>glBlendEquationSeparate</refname> | |
17 | <refpurpose>set the RGB blend equation and the alpha blend equation separately</refpurpose> | |
18 | </refnamediv> | |
19 | <refsynopsisdiv><title>C Specification</title> | |
20 | <funcsynopsis> | |
21 | <funcprototype> | |
22 | <funcdef>void <function>glBlendEquationSeparate</function></funcdef> | |
23 | <paramdef>GLenum <parameter>modeRGB</parameter></paramdef> | |
24 | <paramdef>GLenum <parameter>modeAlpha</parameter></paramdef> | |
25 | </funcprototype> | |
26 | <funcprototype> | |
27 | <funcdef>void <function>glBlendEquationSeparatei</function></funcdef> | |
28 | <paramdef>GLuint <parameter>buf</parameter></paramdef> | |
29 | <paramdef>GLenum <parameter>modeRGB</parameter></paramdef> | |
30 | <paramdef>GLenum <parameter>modeAlpha</parameter></paramdef> | |
31 | </funcprototype> | |
32 | </funcsynopsis> | |
33 | </refsynopsisdiv> | |
34 | <!-- eqn: ignoring delim $$ --> | |
35 | <refsect1 id="parameters"><title>Parameters</title> | |
36 | <variablelist> | |
37 | <varlistentry> | |
38 | <term><parameter>buf</parameter></term> | |
39 | <listitem> | |
40 | <para> | |
41 | for <function>glBlendEquationSeparatei</function>, specifies the index of the draw buffer for which | |
42 | to set the blend equations. | |
43 | </para> | |
44 | </listitem> | |
45 | </varlistentry> | |
46 | <varlistentry> | |
47 | <term><parameter>modeRGB</parameter></term> | |
48 | <listitem> | |
49 | <para> | |
50 | specifies the RGB blend equation, how the red, green, and blue components of the source and destination colors are combined. | |
51 | It must be <constant>GL_FUNC_ADD</constant>, <constant>GL_FUNC_SUBTRACT</constant>, | |
52 | <constant>GL_FUNC_REVERSE_SUBTRACT</constant>, <constant>GL_MIN</constant>, <constant>GL_MAX</constant>. | |
53 | </para> | |
54 | </listitem> | |
55 | </varlistentry> | |
56 | <varlistentry> | |
57 | <term><parameter>modeAlpha</parameter></term> | |
58 | <listitem> | |
59 | <para> | |
60 | specifies the alpha blend equation, how the alpha component of the source and destination colors are combined. | |
61 | It must be <constant>GL_FUNC_ADD</constant>, <constant>GL_FUNC_SUBTRACT</constant>, | |
62 | <constant>GL_FUNC_REVERSE_SUBTRACT</constant>, <constant>GL_MIN</constant>, <constant>GL_MAX</constant>. | |
63 | </para> | |
64 | </listitem> | |
65 | </varlistentry> | |
66 | </variablelist> | |
67 | </refsect1> | |
68 | <refsect1 id="description"><title>Description</title> | |
69 | <para> | |
70 | The blend equations determines how a new pixel (the ''source'' color) | |
71 | is combined with a pixel already in the framebuffer (the ''destination'' | |
72 | color). These functions specifie one blend equation for the RGB-color | |
73 | components and one blend equation for the alpha component. <function>glBlendEquationSeparatei</function> | |
74 | specifies the blend equations for a single draw buffer whereas <function>glBlendEquationSeparate</function> | |
75 | sets the blend equations for all draw buffers. | |
76 | </para> | |
77 | <para> | |
78 | The blend equations use the source and destination blend factors | |
79 | specified by either <citerefentry><refentrytitle>glBlendFunc</refentrytitle></citerefentry> or | |
80 | <citerefentry><refentrytitle>glBlendFuncSeparate</refentrytitle></citerefentry>. | |
81 | See <citerefentry><refentrytitle>glBlendFunc</refentrytitle></citerefentry> or <citerefentry><refentrytitle>glBlendFuncSeparate</refentrytitle></citerefentry> | |
82 | for a description of the various blend factors. | |
83 | </para> | |
84 | <para> | |
85 | In the equations that follow, source and destination | |
86 | color components are referred to as | |
87 | <inlineequation><mml:math> | |
88 | <!-- eqn: ( R sub s, G sub s, B sub s, A sub s ):--> | |
89 | <mml:mfenced open="(" close=")"> | |
90 | <mml:msub><mml:mi mathvariant="italic">R</mml:mi> | |
91 | <mml:mi mathvariant="italic">s</mml:mi> | |
92 | </mml:msub> | |
93 | <mml:msub><mml:mi mathvariant="italic">G</mml:mi> | |
94 | <mml:mi mathvariant="italic">s</mml:mi> | |
95 | </mml:msub> | |
96 | <mml:msub><mml:mi mathvariant="italic">B</mml:mi> | |
97 | <mml:mi mathvariant="italic">s</mml:mi> | |
98 | </mml:msub> | |
99 | <mml:msub><mml:mi mathvariant="italic">A</mml:mi> | |
100 | <mml:mi mathvariant="italic">s</mml:mi> | |
101 | </mml:msub> | |
102 | </mml:mfenced> | |
103 | </mml:math></inlineequation> | |
104 | and | |
105 | <inlineequation><mml:math> | |
106 | <!-- eqn: ( R sub d, G sub d, B sub d, A sub d ):--> | |
107 | <mml:mfenced open="(" close=")"> | |
108 | <mml:msub><mml:mi mathvariant="italic">R</mml:mi> | |
109 | <mml:mi mathvariant="italic">d</mml:mi> | |
110 | </mml:msub> | |
111 | <mml:msub><mml:mi mathvariant="italic">G</mml:mi> | |
112 | <mml:mi mathvariant="italic">d</mml:mi> | |
113 | </mml:msub> | |
114 | <mml:msub><mml:mi mathvariant="italic">B</mml:mi> | |
115 | <mml:mi mathvariant="italic">d</mml:mi> | |
116 | </mml:msub> | |
117 | <mml:msub><mml:mi mathvariant="italic">A</mml:mi> | |
118 | <mml:mi mathvariant="italic">d</mml:mi> | |
119 | </mml:msub> | |
120 | </mml:mfenced> | |
121 | </mml:math></inlineequation>, | |
122 | respectively. | |
123 | The result color is referred to as | |
124 | <inlineequation><mml:math> | |
125 | <!-- eqn: ( R sub r, G sub r, B sub r, A sub r ):--> | |
126 | <mml:mfenced open="(" close=")"> | |
127 | <mml:msub><mml:mi mathvariant="italic">R</mml:mi> | |
128 | <mml:mi mathvariant="italic">r</mml:mi> | |
129 | </mml:msub> | |
130 | <mml:msub><mml:mi mathvariant="italic">G</mml:mi> | |
131 | <mml:mi mathvariant="italic">r</mml:mi> | |
132 | </mml:msub> | |
133 | <mml:msub><mml:mi mathvariant="italic">B</mml:mi> | |
134 | <mml:mi mathvariant="italic">r</mml:mi> | |
135 | </mml:msub> | |
136 | <mml:msub><mml:mi mathvariant="italic">A</mml:mi> | |
137 | <mml:mi mathvariant="italic">r</mml:mi> | |
138 | </mml:msub> | |
139 | </mml:mfenced> | |
140 | </mml:math></inlineequation>. | |
141 | The source and destination blend factors are denoted | |
142 | <inlineequation><mml:math> | |
143 | <!-- eqn: ( s sub R, s sub G, s sub B, s sub A ):--> | |
144 | <mml:mfenced open="(" close=")"> | |
145 | <mml:msub><mml:mi mathvariant="italic">s</mml:mi> | |
146 | <mml:mi mathvariant="italic">R</mml:mi> | |
147 | </mml:msub> | |
148 | <mml:msub><mml:mi mathvariant="italic">s</mml:mi> | |
149 | <mml:mi mathvariant="italic">G</mml:mi> | |
150 | </mml:msub> | |
151 | <mml:msub><mml:mi mathvariant="italic">s</mml:mi> | |
152 | <mml:mi mathvariant="italic">B</mml:mi> | |
153 | </mml:msub> | |
154 | <mml:msub><mml:mi mathvariant="italic">s</mml:mi> | |
155 | <mml:mi mathvariant="italic">A</mml:mi> | |
156 | </mml:msub> | |
157 | </mml:mfenced> | |
158 | </mml:math></inlineequation> | |
159 | and | |
160 | <inlineequation><mml:math> | |
161 | <!-- eqn: ( d sub R, d sub G, d sub B, d sub A ):--> | |
162 | <mml:mfenced open="(" close=")"> | |
163 | <mml:msub><mml:mi mathvariant="italic">d</mml:mi> | |
164 | <mml:mi mathvariant="italic">R</mml:mi> | |
165 | </mml:msub> | |
166 | <mml:msub><mml:mi mathvariant="italic">d</mml:mi> | |
167 | <mml:mi mathvariant="italic">G</mml:mi> | |
168 | </mml:msub> | |
169 | <mml:msub><mml:mi mathvariant="italic">d</mml:mi> | |
170 | <mml:mi mathvariant="italic">B</mml:mi> | |
171 | </mml:msub> | |
172 | <mml:msub><mml:mi mathvariant="italic">d</mml:mi> | |
173 | <mml:mi mathvariant="italic">A</mml:mi> | |
174 | </mml:msub> | |
175 | </mml:mfenced> | |
176 | </mml:math></inlineequation>, | |
177 | respectively. | |
178 | For these equations all color components are understood to have values | |
179 | in the range | |
180 | <inlineequation><mml:math> | |
181 | <!-- eqn: [0,1]:--> | |
182 | <mml:mfenced open="[" close="]"> | |
183 | <mml:mn>0</mml:mn> | |
184 | <mml:mn>1</mml:mn> | |
185 | </mml:mfenced> | |
186 | </mml:math></inlineequation>. | |
187 | ||
188 | <informaltable frame="topbot"> | |
189 | <tgroup cols="3" align="left"> | |
190 | <colspec colwidth="1.1*" /> | |
191 | <colspec colwidth="1*" /> | |
192 | <colspec colwidth="1*" /> | |
193 | <thead> | |
194 | <row> | |
195 | <entry rowsep="1" align="left"><emphasis role="bold"> | |
196 | Mode | |
197 | </emphasis></entry> | |
198 | <entry rowsep="1" align="left"><emphasis role="bold"> | |
199 | RGB Components | |
200 | </emphasis></entry> | |
201 | <entry rowsep="1" align="left"><emphasis role="bold"> | |
202 | Alpha Component | |
203 | </emphasis></entry> | |
204 | </row> | |
205 | </thead> | |
206 | <tbody> | |
207 | <row> | |
208 | <entry align="left"> | |
209 | <constant>GL_FUNC_ADD</constant> | |
210 | </entry> | |
211 | <entry align="left"> | |
212 | <informalequation><mml:math> | |
213 | <!-- eqn: Rr = R sub s s sub R + R sub d d sub R :--> | |
214 | <mml:mrow> | |
215 | <mml:mi mathvariant="italic">Rr</mml:mi> | |
216 | <mml:mo>=</mml:mo> | |
217 | <mml:mrow> | |
218 | <mml:msub><mml:mi mathvariant="italic">R</mml:mi> | |
219 | <mml:mi mathvariant="italic">s</mml:mi> | |
220 | </mml:msub> | |
221 | <mml:mo>⁢</mml:mo> | |
222 | <mml:msub><mml:mi mathvariant="italic">s</mml:mi> | |
223 | <mml:mi mathvariant="italic">R</mml:mi> | |
224 | </mml:msub> | |
225 | <mml:mo>+</mml:mo> | |
226 | <mml:msub><mml:mi mathvariant="italic">R</mml:mi> | |
227 | <mml:mi mathvariant="italic">d</mml:mi> | |
228 | </mml:msub> | |
229 | <mml:mo>⁢</mml:mo> | |
230 | <mml:msub><mml:mi mathvariant="italic">d</mml:mi> | |
231 | <mml:mi mathvariant="italic">R</mml:mi> | |
232 | </mml:msub> | |
233 | </mml:mrow> | |
234 | </mml:mrow> | |
235 | </mml:math></informalequation> | |
236 | <informalequation><mml:math> | |
237 | <!-- eqn: Gr = G sub s s sub G + G sub d d sub G :--> | |
238 | <mml:mrow> | |
239 | <mml:mi mathvariant="italic">Gr</mml:mi> | |
240 | <mml:mo>=</mml:mo> | |
241 | <mml:mrow> | |
242 | <mml:msub><mml:mi mathvariant="italic">G</mml:mi> | |
243 | <mml:mi mathvariant="italic">s</mml:mi> | |
244 | </mml:msub> | |
245 | <mml:mo>⁢</mml:mo> | |
246 | <mml:msub><mml:mi mathvariant="italic">s</mml:mi> | |
247 | <mml:mi mathvariant="italic">G</mml:mi> | |
248 | </mml:msub> | |
249 | <mml:mo>+</mml:mo> | |
250 | <mml:msub><mml:mi mathvariant="italic">G</mml:mi> | |
251 | <mml:mi mathvariant="italic">d</mml:mi> | |
252 | </mml:msub> | |
253 | <mml:mo>⁢</mml:mo> | |
254 | <mml:msub><mml:mi mathvariant="italic">d</mml:mi> | |
255 | <mml:mi mathvariant="italic">G</mml:mi> | |
256 | </mml:msub> | |
257 | </mml:mrow> | |
258 | </mml:mrow> | |
259 | </mml:math></informalequation> | |
260 | <informalequation><mml:math> | |
261 | <!-- eqn: Br = B sub s s sub B + B sub d d sub B :--> | |
262 | <mml:mrow> | |
263 | <mml:mi mathvariant="italic">Br</mml:mi> | |
264 | <mml:mo>=</mml:mo> | |
265 | <mml:mrow> | |
266 | <mml:msub><mml:mi mathvariant="italic">B</mml:mi> | |
267 | <mml:mi mathvariant="italic">s</mml:mi> | |
268 | </mml:msub> | |
269 | <mml:mo>⁢</mml:mo> | |
270 | <mml:msub><mml:mi mathvariant="italic">s</mml:mi> | |
271 | <mml:mi mathvariant="italic">B</mml:mi> | |
272 | </mml:msub> | |
273 | <mml:mo>+</mml:mo> | |
274 | <mml:msub><mml:mi mathvariant="italic">B</mml:mi> | |
275 | <mml:mi mathvariant="italic">d</mml:mi> | |
276 | </mml:msub> | |
277 | <mml:mo>⁢</mml:mo> | |
278 | <mml:msub><mml:mi mathvariant="italic">d</mml:mi> | |
279 | <mml:mi mathvariant="italic">B</mml:mi> | |
280 | </mml:msub> | |
281 | </mml:mrow> | |
282 | </mml:mrow> | |
283 | </mml:math></informalequation> | |
284 | </entry> | |
285 | <entry align="left"> | |
286 | <informalequation><mml:math> | |
287 | <!-- eqn: Ar = A sub s s sub A + A sub d d sub A :--> | |
288 | <mml:mrow> | |
289 | <mml:mi mathvariant="italic">Ar</mml:mi> | |
290 | <mml:mo>=</mml:mo> | |
291 | <mml:mrow> | |
292 | <mml:msub><mml:mi mathvariant="italic">A</mml:mi> | |
293 | <mml:mi mathvariant="italic">s</mml:mi> | |
294 | </mml:msub> | |
295 | <mml:mo>⁢</mml:mo> | |
296 | <mml:msub><mml:mi mathvariant="italic">s</mml:mi> | |
297 | <mml:mi mathvariant="italic">A</mml:mi> | |
298 | </mml:msub> | |
299 | <mml:mo>+</mml:mo> | |
300 | <mml:msub><mml:mi mathvariant="italic">A</mml:mi> | |
301 | <mml:mi mathvariant="italic">d</mml:mi> | |
302 | </mml:msub> | |
303 | <mml:mo>⁢</mml:mo> | |
304 | <mml:msub><mml:mi mathvariant="italic">d</mml:mi> | |
305 | <mml:mi mathvariant="italic">A</mml:mi> | |
306 | </mml:msub> | |
307 | </mml:mrow> | |
308 | </mml:mrow> | |
309 | </mml:math></informalequation> | |
310 | </entry> | |
311 | </row> | |
312 | <row> | |
313 | <entry align="left"> | |
314 | <constant>GL_FUNC_SUBTRACT</constant> | |
315 | </entry> | |
316 | <entry align="left"> | |
317 | <informalequation><mml:math> | |
318 | <!-- eqn: Rr = R sub s s sub R - R sub d d sub R :--> | |
319 | <mml:mrow> | |
320 | <mml:mi mathvariant="italic">Rr</mml:mi> | |
321 | <mml:mo>=</mml:mo> | |
322 | <mml:mrow> | |
323 | <mml:msub><mml:mi mathvariant="italic">R</mml:mi> | |
324 | <mml:mi mathvariant="italic">s</mml:mi> | |
325 | </mml:msub> | |
326 | <mml:mo>⁢</mml:mo> | |
327 | <mml:msub><mml:mi mathvariant="italic">s</mml:mi> | |
328 | <mml:mi mathvariant="italic">R</mml:mi> | |
329 | </mml:msub> | |
330 | <mml:mo>-</mml:mo> | |
331 | <mml:msub><mml:mi mathvariant="italic">R</mml:mi> | |
332 | <mml:mi mathvariant="italic">d</mml:mi> | |
333 | </mml:msub> | |
334 | <mml:mo>⁢</mml:mo> | |
335 | <mml:msub><mml:mi mathvariant="italic">d</mml:mi> | |
336 | <mml:mi mathvariant="italic">R</mml:mi> | |
337 | </mml:msub> | |
338 | </mml:mrow> | |
339 | </mml:mrow> | |
340 | </mml:math></informalequation> | |
341 | <informalequation><mml:math> | |
342 | <!-- eqn: Gr = G sub s s sub G - G sub d d sub G :--> | |
343 | <mml:mrow> | |
344 | <mml:mi mathvariant="italic">Gr</mml:mi> | |
345 | <mml:mo>=</mml:mo> | |
346 | <mml:mrow> | |
347 | <mml:msub><mml:mi mathvariant="italic">G</mml:mi> | |
348 | <mml:mi mathvariant="italic">s</mml:mi> | |
349 | </mml:msub> | |
350 | <mml:mo>⁢</mml:mo> | |
351 | <mml:msub><mml:mi mathvariant="italic">s</mml:mi> | |
352 | <mml:mi mathvariant="italic">G</mml:mi> | |
353 | </mml:msub> | |
354 | <mml:mo>-</mml:mo> | |
355 | <mml:msub><mml:mi mathvariant="italic">G</mml:mi> | |
356 | <mml:mi mathvariant="italic">d</mml:mi> | |
357 | </mml:msub> | |
358 | <mml:mo>⁢</mml:mo> | |
359 | <mml:msub><mml:mi mathvariant="italic">d</mml:mi> | |
360 | <mml:mi mathvariant="italic">G</mml:mi> | |
361 | </mml:msub> | |
362 | </mml:mrow> | |
363 | </mml:mrow> | |
364 | </mml:math></informalequation> | |
365 | <informalequation><mml:math> | |
366 | <!-- eqn: Br = B sub s s sub B - B sub d d sub B :--> | |
367 | <mml:mrow> | |
368 | <mml:mi mathvariant="italic">Br</mml:mi> | |
369 | <mml:mo>=</mml:mo> | |
370 | <mml:mrow> | |
371 | <mml:msub><mml:mi mathvariant="italic">B</mml:mi> | |
372 | <mml:mi mathvariant="italic">s</mml:mi> | |
373 | </mml:msub> | |
374 | <mml:mo>⁢</mml:mo> | |
375 | <mml:msub><mml:mi mathvariant="italic">s</mml:mi> | |
376 | <mml:mi mathvariant="italic">B</mml:mi> | |
377 | </mml:msub> | |
378 | <mml:mo>-</mml:mo> | |
379 | <mml:msub><mml:mi mathvariant="italic">B</mml:mi> | |
380 | <mml:mi mathvariant="italic">d</mml:mi> | |
381 | </mml:msub> | |
382 | <mml:mo>⁢</mml:mo> | |
383 | <mml:msub><mml:mi mathvariant="italic">d</mml:mi> | |
384 | <mml:mi mathvariant="italic">B</mml:mi> | |
385 | </mml:msub> | |
386 | </mml:mrow> | |
387 | </mml:mrow> | |
388 | </mml:math></informalequation> | |
389 | </entry> | |
390 | <entry align="left"> | |
391 | <informalequation><mml:math> | |
392 | <!-- eqn: Ar = A sub s s sub A - A sub d d sub A :--> | |
393 | <mml:mrow> | |
394 | <mml:mi mathvariant="italic">Ar</mml:mi> | |
395 | <mml:mo>=</mml:mo> | |
396 | <mml:mrow> | |
397 | <mml:msub><mml:mi mathvariant="italic">A</mml:mi> | |
398 | <mml:mi mathvariant="italic">s</mml:mi> | |
399 | </mml:msub> | |
400 | <mml:mo>⁢</mml:mo> | |
401 | <mml:msub><mml:mi mathvariant="italic">s</mml:mi> | |
402 | <mml:mi mathvariant="italic">A</mml:mi> | |
403 | </mml:msub> | |
404 | <mml:mo>-</mml:mo> | |
405 | <mml:msub><mml:mi mathvariant="italic">A</mml:mi> | |
406 | <mml:mi mathvariant="italic">d</mml:mi> | |
407 | </mml:msub> | |
408 | <mml:mo>⁢</mml:mo> | |
409 | <mml:msub><mml:mi mathvariant="italic">d</mml:mi> | |
410 | <mml:mi mathvariant="italic">A</mml:mi> | |
411 | </mml:msub> | |
412 | </mml:mrow> | |
413 | </mml:mrow> | |
414 | </mml:math></informalequation> | |
415 | </entry> | |
416 | </row> | |
417 | <row> | |
418 | <entry align="left"> | |
419 | <constant>GL_FUNC_REVERSE_SUBTRACT</constant> | |
420 | </entry> | |
421 | <entry align="left"> | |
422 | <informalequation><mml:math> | |
423 | <!-- eqn: Rr = R sub d d sub R - R sub s s sub R :--> | |
424 | <mml:mrow> | |
425 | <mml:mi mathvariant="italic">Rr</mml:mi> | |
426 | <mml:mo>=</mml:mo> | |
427 | <mml:mrow> | |
428 | <mml:msub><mml:mi mathvariant="italic">R</mml:mi> | |
429 | <mml:mi mathvariant="italic">d</mml:mi> | |
430 | </mml:msub> | |
431 | <mml:mo>⁢</mml:mo> | |
432 | <mml:msub><mml:mi mathvariant="italic">d</mml:mi> | |
433 | <mml:mi mathvariant="italic">R</mml:mi> | |
434 | </mml:msub> | |
435 | <mml:mo>-</mml:mo> | |
436 | <mml:msub><mml:mi mathvariant="italic">R</mml:mi> | |
437 | <mml:mi mathvariant="italic">s</mml:mi> | |
438 | </mml:msub> | |
439 | <mml:mo>⁢</mml:mo> | |
440 | <mml:msub><mml:mi mathvariant="italic">s</mml:mi> | |
441 | <mml:mi mathvariant="italic">R</mml:mi> | |
442 | </mml:msub> | |
443 | </mml:mrow> | |
444 | </mml:mrow> | |
445 | </mml:math></informalequation> | |
446 | <informalequation><mml:math> | |
447 | <!-- eqn: Gr = G sub d d sub G - G sub s s sub G :--> | |
448 | <mml:mrow> | |
449 | <mml:mi mathvariant="italic">Gr</mml:mi> | |
450 | <mml:mo>=</mml:mo> | |
451 | <mml:mrow> | |
452 | <mml:msub><mml:mi mathvariant="italic">G</mml:mi> | |
453 | <mml:mi mathvariant="italic">d</mml:mi> | |
454 | </mml:msub> | |
455 | <mml:mo>⁢</mml:mo> | |
456 | <mml:msub><mml:mi mathvariant="italic">d</mml:mi> | |
457 | <mml:mi mathvariant="italic">G</mml:mi> | |
458 | </mml:msub> | |
459 | <mml:mo>-</mml:mo> | |
460 | <mml:msub><mml:mi mathvariant="italic">G</mml:mi> | |
461 | <mml:mi mathvariant="italic">s</mml:mi> | |
462 | </mml:msub> | |
463 | <mml:mo>⁢</mml:mo> | |
464 | <mml:msub><mml:mi mathvariant="italic">s</mml:mi> | |
465 | <mml:mi mathvariant="italic">G</mml:mi> | |
466 | </mml:msub> | |
467 | </mml:mrow> | |
468 | </mml:mrow> | |
469 | </mml:math></informalequation> | |
470 | <informalequation><mml:math> | |
471 | <!-- eqn: Br = B sub d d sub B - B sub s s sub B :--> | |
472 | <mml:mrow> | |
473 | <mml:mi mathvariant="italic">Br</mml:mi> | |
474 | <mml:mo>=</mml:mo> | |
475 | <mml:mrow> | |
476 | <mml:msub><mml:mi mathvariant="italic">B</mml:mi> | |
477 | <mml:mi mathvariant="italic">d</mml:mi> | |
478 | </mml:msub> | |
479 | <mml:mo>⁢</mml:mo> | |
480 | <mml:msub><mml:mi mathvariant="italic">d</mml:mi> | |
481 | <mml:mi mathvariant="italic">B</mml:mi> | |
482 | </mml:msub> | |
483 | <mml:mo>-</mml:mo> | |
484 | <mml:msub><mml:mi mathvariant="italic">B</mml:mi> | |
485 | <mml:mi mathvariant="italic">s</mml:mi> | |
486 | </mml:msub> | |
487 | <mml:mo>⁢</mml:mo> | |
488 | <mml:msub><mml:mi mathvariant="italic">s</mml:mi> | |
489 | <mml:mi mathvariant="italic">B</mml:mi> | |
490 | </mml:msub> | |
491 | </mml:mrow> | |
492 | </mml:mrow> | |
493 | </mml:math></informalequation> | |
494 | </entry> | |
495 | <entry align="left"> | |
496 | <informalequation><mml:math> | |
497 | <!-- eqn: Ar = A sub d d sub A - A sub s s sub A :--> | |
498 | <mml:mrow> | |
499 | <mml:mi mathvariant="italic">Ar</mml:mi> | |
500 | <mml:mo>=</mml:mo> | |
501 | <mml:mrow> | |
502 | <mml:msub><mml:mi mathvariant="italic">A</mml:mi> | |
503 | <mml:mi mathvariant="italic">d</mml:mi> | |
504 | </mml:msub> | |
505 | <mml:mo>⁢</mml:mo> | |
506 | <mml:msub><mml:mi mathvariant="italic">d</mml:mi> | |
507 | <mml:mi mathvariant="italic">A</mml:mi> | |
508 | </mml:msub> | |
509 | <mml:mo>-</mml:mo> | |
510 | <mml:msub><mml:mi mathvariant="italic">A</mml:mi> | |
511 | <mml:mi mathvariant="italic">s</mml:mi> | |
512 | </mml:msub> | |
513 | <mml:mo>⁢</mml:mo> | |
514 | <mml:msub><mml:mi mathvariant="italic">s</mml:mi> | |
515 | <mml:mi mathvariant="italic">A</mml:mi> | |
516 | </mml:msub> | |
517 | </mml:mrow> | |
518 | </mml:mrow> | |
519 | </mml:math></informalequation> | |
520 | </entry> | |
521 | </row> | |
522 | <row> | |
523 | <entry align="left"> | |
524 | <constant>GL_MIN</constant> | |
525 | </entry> | |
526 | <entry align="left"> | |
527 | <informalequation><mml:math> | |
528 | <!-- eqn: Rr = min ( R sub s, R sub d):--> | |
529 | <mml:mrow> | |
530 | <mml:mi mathvariant="italic">Rr</mml:mi> | |
531 | <mml:mo>=</mml:mo> | |
532 | <mml:mrow> | |
533 | <mml:mi mathvariant="italic">min</mml:mi> | |
534 | <mml:mo>⁡</mml:mo> | |
535 | <mml:mfenced open="(" close=")"> | |
536 | <mml:mrow> | |
537 | <mml:msub><mml:mi mathvariant="italic">R</mml:mi> | |
538 | <mml:mi mathvariant="italic">s</mml:mi> | |
539 | </mml:msub> | |
540 | </mml:mrow> | |
541 | <mml:mrow> | |
542 | <mml:msub><mml:mi mathvariant="italic">R</mml:mi> | |
543 | <mml:mi mathvariant="italic">d</mml:mi> | |
544 | </mml:msub> | |
545 | </mml:mrow> | |
546 | </mml:mfenced> | |
547 | </mml:mrow> | |
548 | </mml:mrow> | |
549 | </mml:math></informalequation> | |
550 | <informalequation><mml:math> | |
551 | <!-- eqn: Gr = min ( G sub s, G sub d):--> | |
552 | <mml:mrow> | |
553 | <mml:mi mathvariant="italic">Gr</mml:mi> | |
554 | <mml:mo>=</mml:mo> | |
555 | <mml:mrow> | |
556 | <mml:mi mathvariant="italic">min</mml:mi> | |
557 | <mml:mo>⁡</mml:mo> | |
558 | <mml:mfenced open="(" close=")"> | |
559 | <mml:mrow> | |
560 | <mml:msub><mml:mi mathvariant="italic">G</mml:mi> | |
561 | <mml:mi mathvariant="italic">s</mml:mi> | |
562 | </mml:msub> | |
563 | </mml:mrow> | |
564 | <mml:mrow> | |
565 | <mml:msub><mml:mi mathvariant="italic">G</mml:mi> | |
566 | <mml:mi mathvariant="italic">d</mml:mi> | |
567 | </mml:msub> | |
568 | </mml:mrow> | |
569 | </mml:mfenced> | |
570 | </mml:mrow> | |
571 | </mml:mrow> | |
572 | </mml:math></informalequation> | |
573 | <informalequation><mml:math> | |
574 | <!-- eqn: Br = min ( B sub s, B sub d):--> | |
575 | <mml:mrow> | |
576 | <mml:mi mathvariant="italic">Br</mml:mi> | |
577 | <mml:mo>=</mml:mo> | |
578 | <mml:mrow> | |
579 | <mml:mi mathvariant="italic">min</mml:mi> | |
580 | <mml:mo>⁡</mml:mo> | |
581 | <mml:mfenced open="(" close=")"> | |
582 | <mml:mrow> | |
583 | <mml:msub><mml:mi mathvariant="italic">B</mml:mi> | |
584 | <mml:mi mathvariant="italic">s</mml:mi> | |
585 | </mml:msub> | |
586 | </mml:mrow> | |
587 | <mml:mrow> | |
588 | <mml:msub><mml:mi mathvariant="italic">B</mml:mi> | |
589 | <mml:mi mathvariant="italic">d</mml:mi> | |
590 | </mml:msub> | |
591 | </mml:mrow> | |
592 | </mml:mfenced> | |
593 | </mml:mrow> | |
594 | </mml:mrow> | |
595 | </mml:math></informalequation> | |
596 | </entry> | |
597 | <entry align="left"> | |
598 | <informalequation><mml:math> | |
599 | <!-- eqn: Ar = min ( A sub s, A sub d):--> | |
600 | <mml:mrow> | |
601 | <mml:mi mathvariant="italic">Ar</mml:mi> | |
602 | <mml:mo>=</mml:mo> | |
603 | <mml:mrow> | |
604 | <mml:mi mathvariant="italic">min</mml:mi> | |
605 | <mml:mo>⁡</mml:mo> | |
606 | <mml:mfenced open="(" close=")"> | |
607 | <mml:mrow> | |
608 | <mml:msub><mml:mi mathvariant="italic">A</mml:mi> | |
609 | <mml:mi mathvariant="italic">s</mml:mi> | |
610 | </mml:msub> | |
611 | </mml:mrow> | |
612 | <mml:mrow> | |
613 | <mml:msub><mml:mi mathvariant="italic">A</mml:mi> | |
614 | <mml:mi mathvariant="italic">d</mml:mi> | |
615 | </mml:msub> | |
616 | </mml:mrow> | |
617 | </mml:mfenced> | |
618 | </mml:mrow> | |
619 | </mml:mrow> | |
620 | </mml:math></informalequation> | |
621 | </entry> | |
622 | </row> | |
623 | <row> | |
624 | <entry align="left"> | |
625 | <constant>GL_MAX</constant> | |
626 | </entry> | |
627 | <entry align="left"> | |
628 | <informalequation><mml:math> | |
629 | <!-- eqn: Rr = max ( R sub s, R sub d):--> | |
630 | <mml:mrow> | |
631 | <mml:mi mathvariant="italic">Rr</mml:mi> | |
632 | <mml:mo>=</mml:mo> | |
633 | <mml:mrow> | |
634 | <mml:mi mathvariant="italic">max</mml:mi> | |
635 | <mml:mo>⁡</mml:mo> | |
636 | <mml:mfenced open="(" close=")"> | |
637 | <mml:mrow> | |
638 | <mml:msub><mml:mi mathvariant="italic">R</mml:mi> | |
639 | <mml:mi mathvariant="italic">s</mml:mi> | |
640 | </mml:msub> | |
641 | </mml:mrow> | |
642 | <mml:mrow> | |
643 | <mml:msub><mml:mi mathvariant="italic">R</mml:mi> | |
644 | <mml:mi mathvariant="italic">d</mml:mi> | |
645 | </mml:msub> | |
646 | </mml:mrow> | |
647 | </mml:mfenced> | |
648 | </mml:mrow> | |
649 | </mml:mrow> | |
650 | </mml:math></informalequation> | |
651 | <informalequation><mml:math> | |
652 | <!-- eqn: Gr = max ( G sub s, G sub d):--> | |
653 | <mml:mrow> | |
654 | <mml:mi mathvariant="italic">Gr</mml:mi> | |
655 | <mml:mo>=</mml:mo> | |
656 | <mml:mrow> | |
657 | <mml:mi mathvariant="italic">max</mml:mi> | |
658 | <mml:mo>⁡</mml:mo> | |
659 | <mml:mfenced open="(" close=")"> | |
660 | <mml:mrow> | |
661 | <mml:msub><mml:mi mathvariant="italic">G</mml:mi> | |
662 | <mml:mi mathvariant="italic">s</mml:mi> | |
663 | </mml:msub> | |
664 | </mml:mrow> | |
665 | <mml:mrow> | |
666 | <mml:msub><mml:mi mathvariant="italic">G</mml:mi> | |
667 | <mml:mi mathvariant="italic">d</mml:mi> | |
668 | </mml:msub> | |
669 | </mml:mrow> | |
670 | </mml:mfenced> | |
671 | </mml:mrow> | |
672 | </mml:mrow> | |
673 | </mml:math></informalequation> | |
674 | <informalequation><mml:math> | |
675 | <!-- eqn: Br = max ( B sub s, B sub d):--> | |
676 | <mml:mrow> | |
677 | <mml:mi mathvariant="italic">Br</mml:mi> | |
678 | <mml:mo>=</mml:mo> | |
679 | <mml:mrow> | |
680 | <mml:mi mathvariant="italic">max</mml:mi> | |
681 | <mml:mo>⁡</mml:mo> | |
682 | <mml:mfenced open="(" close=")"> | |
683 | <mml:mrow> | |
684 | <mml:msub><mml:mi mathvariant="italic">B</mml:mi> | |
685 | <mml:mi mathvariant="italic">s</mml:mi> | |
686 | </mml:msub> | |
687 | </mml:mrow> | |
688 | <mml:mrow> | |
689 | <mml:msub><mml:mi mathvariant="italic">B</mml:mi> | |
690 | <mml:mi mathvariant="italic">d</mml:mi> | |
691 | </mml:msub> | |
692 | </mml:mrow> | |
693 | </mml:mfenced> | |
694 | </mml:mrow> | |
695 | </mml:mrow> | |
696 | </mml:math></informalequation> | |
697 | </entry> | |
698 | <entry align="left"> | |
699 | <informalequation><mml:math> | |
700 | <!-- eqn: Ar = max ( A sub s, A sub d):--> | |
701 | <mml:mrow> | |
702 | <mml:mi mathvariant="italic">Ar</mml:mi> | |
703 | <mml:mo>=</mml:mo> | |
704 | <mml:mrow> | |
705 | <mml:mi mathvariant="italic">max</mml:mi> | |
706 | <mml:mo>⁡</mml:mo> | |
707 | <mml:mfenced open="(" close=")"> | |
708 | <mml:mrow> | |
709 | <mml:msub><mml:mi mathvariant="italic">A</mml:mi> | |
710 | <mml:mi mathvariant="italic">s</mml:mi> | |
711 | </mml:msub> | |
712 | </mml:mrow> | |
713 | <mml:mrow> | |
714 | <mml:msub><mml:mi mathvariant="italic">A</mml:mi> | |
715 | <mml:mi mathvariant="italic">d</mml:mi> | |
716 | </mml:msub> | |
717 | </mml:mrow> | |
718 | </mml:mfenced> | |
719 | </mml:mrow> | |
720 | </mml:mrow> | |
721 | </mml:math></informalequation> | |
722 | </entry> | |
723 | </row> | |
724 | </tbody> | |
725 | </tgroup> | |
726 | </informaltable> | |
727 | </para> | |
728 | <para> | |
729 | The results of these equations are clamped to the range | |
730 | <inlineequation><mml:math> | |
731 | <!-- eqn: [0,1]:--> | |
732 | <mml:mfenced open="[" close="]"> | |
733 | <mml:mn>0</mml:mn> | |
734 | <mml:mn>1</mml:mn> | |
735 | </mml:mfenced> | |
736 | </mml:math></inlineequation>. | |
737 | </para> | |
738 | <para> | |
739 | The <constant>GL_MIN</constant> and <constant>GL_MAX</constant> equations are useful for applications | |
740 | that analyze image data (image thresholding against a constant color, | |
741 | for example). | |
742 | The <constant>GL_FUNC_ADD</constant> equation is useful | |
743 | for antialiasing and transparency, among other things. | |
744 | </para> | |
745 | <para> | |
746 | Initially, both the RGB blend equation and the alpha blend equation are set to <constant>GL_FUNC_ADD</constant>. | |
747 | </para> | |
748 | <para> | |
749 | </para> | |
750 | </refsect1> | |
751 | <refsect1 id="notes"><title>Notes</title> | |
752 | <para> | |
753 | The <constant>GL_MIN</constant>, and <constant>GL_MAX</constant> equations do not use | |
754 | the source or destination factors, only the source and destination colors. | |
755 | </para> | |
756 | </refsect1> | |
757 | <refsect1 id="errors"><title>Errors</title> | |
758 | <para> | |
759 | <constant>GL_INVALID_ENUM</constant> is generated if either <parameter>modeRGB</parameter> or <parameter>modeAlpha</parameter> is not one of | |
760 | <constant>GL_FUNC_ADD</constant>, <constant>GL_FUNC_SUBTRACT</constant>, <constant>GL_FUNC_REVERSE_SUBTRACT</constant>, | |
761 | <constant>GL_MAX</constant>, or <constant>GL_MIN</constant>. | |
762 | </para> | |
763 | <para> | |
764 | <constant>GL_INVALID_VALUE</constant> is generated by <function>glBlendEquationSeparatei</function> if <parameter>buf</parameter> is greater | |
765 | than or equal to the value of <constant>GL_MAX_DRAW_BUFFERS</constant>. | |
766 | </para> | |
767 | </refsect1> | |
768 | <refsect1 id="associatedgets"><title>Associated Gets</title> | |
769 | <para> | |
770 | <citerefentry><refentrytitle>glGet</refentrytitle></citerefentry> with an argument of <constant>GL_BLEND_EQUATION_RGB</constant> | |
771 | </para> | |
772 | <para> | |
773 | <citerefentry><refentrytitle>glGet</refentrytitle></citerefentry> with an argument of <constant>GL_BLEND_EQUATION_ALPHA</constant> | |
774 | </para> | |
775 | </refsect1> | |
776 | <refsect1 id="seealso"><title>See Also</title> | |
777 | <para> | |
778 | <citerefentry><refentrytitle>glGetString</refentrytitle></citerefentry>, | |
779 | <citerefentry><refentrytitle>glBlendColor</refentrytitle></citerefentry>, | |
780 | <citerefentry><refentrytitle>glBlendFunc</refentrytitle></citerefentry>, | |
781 | <citerefentry><refentrytitle>glBlendFuncSeparate</refentrytitle></citerefentry> | |
782 | </para> | |
783 | </refsect1> | |
784 | <refsect1 id="Copyright"><title>Copyright</title> | |
785 | <para> | |
786 | Copyright <trademark class="copyright"></trademark> 2006 Khronos Group. | |
787 | This material may be distributed subject to the terms and conditions set forth in | |
788 | the Open Publication License, v 1.0, 8 June 1999. | |
789 | <ulink url="http://opencontent.org/openpub/">http://opencontent.org/openpub/</ulink>. | |
790 | </para> | |
791 | </refsect1> | |
792 | </refentry> |