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