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1 | <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "xhtml1-transitional.dtd"> |
2 | <!-- saved from url=(0013)about:internet --> | |
3 | <?xml-stylesheet type="text/xsl" href="mathml.xsl"?><html xmlns="http://www.w3.org/1999/xhtml" xmlns:pref="http://www.w3.org/2002/Math/preference" pref:renderer="mathplayer-dl"><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /><title>glBlendFunc</title><meta name="generator" content="DocBook XSL Stylesheets V1.73.2" /></head><body><div class="refentry" lang="en" xml:lang="en"><a id="glBlendFunc"></a><div class="titlepage"></div><div class="refnamediv"><h2>Name</h2><p>glBlendFunc — specify pixel arithmetic</p></div><div class="refsynopsisdiv"><h2>C Specification</h2><div class="funcsynopsis"><table border="0" summary="Function synopsis" cellspacing="0" cellpadding="0"><tr><td><code class="funcdef">void <b class="fsfunc">glBlendFunc</b>(</code></td><td>GLenum </td><td><var class="pdparam">sfactor</var>, </td></tr><tr><td> </td><td>GLenum </td><td><var class="pdparam">dfactor</var><code>)</code>;</td></tr></table></div></div><div class="refsect1" lang="en" xml:lang="en"><a id="parameters"></a><h2>Parameters</h2><div class="variablelist"><dl><dt><span class="term"><em class="parameter"><code>sfactor</code></em></span></dt><dd><p> | |
4 | Specifies how the red, green, blue, | |
5 | and alpha source blending factors are computed. | |
6 | The following symbolic constants are accepted: | |
7 | <code class="constant">GL_ZERO</code>, | |
8 | <code class="constant">GL_ONE</code>, | |
9 | <code class="constant">GL_SRC_COLOR</code>, | |
10 | <code class="constant">GL_ONE_MINUS_SRC_COLOR</code>, | |
11 | <code class="constant">GL_DST_COLOR</code>, | |
12 | <code class="constant">GL_ONE_MINUS_DST_COLOR</code>, | |
13 | <code class="constant">GL_SRC_ALPHA</code>, | |
14 | <code class="constant">GL_ONE_MINUS_SRC_ALPHA</code>, | |
15 | <code class="constant">GL_DST_ALPHA</code>, | |
16 | <code class="constant">GL_ONE_MINUS_DST_ALPHA</code>, | |
17 | <code class="constant">GL_CONSTANT_COLOR</code>, | |
18 | <code class="constant">GL_ONE_MINUS_CONSTANT_COLOR</code>, | |
19 | <code class="constant">GL_CONSTANT_ALPHA</code>, | |
20 | <code class="constant">GL_ONE_MINUS_CONSTANT_ALPHA</code>, and | |
21 | <code class="constant">GL_SRC_ALPHA_SATURATE</code>. | |
22 | The initial value is <code class="constant">GL_ONE</code>. | |
23 | </p></dd><dt><span class="term"><em class="parameter"><code>dfactor</code></em></span></dt><dd><p> | |
24 | Specifies how the red, green, blue, | |
25 | and alpha destination blending factors are computed. | |
26 | The following symbolic constants are accepted: | |
27 | <code class="constant">GL_ZERO</code>, | |
28 | <code class="constant">GL_ONE</code>, | |
29 | <code class="constant">GL_SRC_COLOR</code>, | |
30 | <code class="constant">GL_ONE_MINUS_SRC_COLOR</code>, | |
31 | <code class="constant">GL_DST_COLOR</code>, | |
32 | <code class="constant">GL_ONE_MINUS_DST_COLOR</code>, | |
33 | <code class="constant">GL_SRC_ALPHA</code>, | |
34 | <code class="constant">GL_ONE_MINUS_SRC_ALPHA</code>, | |
35 | <code class="constant">GL_DST_ALPHA</code>, | |
36 | <code class="constant">GL_ONE_MINUS_DST_ALPHA</code>. | |
37 | <code class="constant">GL_CONSTANT_COLOR</code>, | |
38 | <code class="constant">GL_ONE_MINUS_CONSTANT_COLOR</code>, | |
39 | <code class="constant">GL_CONSTANT_ALPHA</code>, and | |
40 | <code class="constant">GL_ONE_MINUS_CONSTANT_ALPHA</code>. | |
41 | The initial value is <code class="constant">GL_ZERO</code>. | |
42 | </p></dd></dl></div></div><div class="refsect1" lang="en" xml:lang="en"><a id="description"></a><h2>Description</h2><p> | |
43 | In RGBA mode, pixels can be drawn using a function that blends | |
44 | the incoming (source) RGBA values with the RGBA values | |
45 | that are already in the frame buffer (the destination values). | |
46 | Blending is initially disabled. | |
47 | Use <a class="citerefentry" href="glEnable.xml"><span class="citerefentry"><span class="refentrytitle">glEnable</span></span></a> and <a class="citerefentry" href="glDisable.xml"><span class="citerefentry"><span class="refentrytitle">glDisable</span></span></a> with argument <code class="constant">GL_BLEND</code> | |
48 | to enable and disable blending. | |
49 | </p><p> | |
50 | <code class="function">glBlendFunc</code> defines the operation of blending when it is enabled. | |
51 | <em class="parameter"><code>sfactor</code></em> specifies which method is used to scale the | |
52 | source color components. | |
53 | <em class="parameter"><code>dfactor</code></em> specifies which method is used to scale the | |
54 | destination color components. | |
55 | The possible methods are described in the following table. | |
56 | Each method defines four scale factors, | |
57 | one each for red, green, blue, and alpha. | |
58 | In the table and in subsequent equations, source and destination | |
59 | color components are referred to as | |
60 | <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> | |
61 | ||
62 | <mml:mfenced open="(" close=")"> | |
63 | <mml:msub><mml:mi mathvariant="italic">R</mml:mi> | |
64 | <mml:mi mathvariant="italic">s</mml:mi> | |
65 | </mml:msub> | |
66 | <mml:msub><mml:mi mathvariant="italic">G</mml:mi> | |
67 | <mml:mi mathvariant="italic">s</mml:mi> | |
68 | </mml:msub> | |
69 | <mml:msub><mml:mi mathvariant="italic">B</mml:mi> | |
70 | <mml:mi mathvariant="italic">s</mml:mi> | |
71 | </mml:msub> | |
72 | <mml:msub><mml:mi mathvariant="italic">A</mml:mi> | |
73 | <mml:mi mathvariant="italic">s</mml:mi> | |
74 | </mml:msub> | |
75 | </mml:mfenced> | |
76 | </mml:math> | |
77 | and | |
78 | <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> | |
79 | ||
80 | <mml:mfenced open="(" close=")"> | |
81 | <mml:msub><mml:mi mathvariant="italic">R</mml:mi> | |
82 | <mml:mi mathvariant="italic">d</mml:mi> | |
83 | </mml:msub> | |
84 | <mml:msub><mml:mi mathvariant="italic">G</mml:mi> | |
85 | <mml:mi mathvariant="italic">d</mml:mi> | |
86 | </mml:msub> | |
87 | <mml:msub><mml:mi mathvariant="italic">B</mml:mi> | |
88 | <mml:mi mathvariant="italic">d</mml:mi> | |
89 | </mml:msub> | |
90 | <mml:msub><mml:mi mathvariant="italic">A</mml:mi> | |
91 | <mml:mi mathvariant="italic">d</mml:mi> | |
92 | </mml:msub> | |
93 | </mml:mfenced> | |
94 | </mml:math>. | |
95 | The color specified by <a class="citerefentry" href="glBlendColor.xml"><span class="citerefentry"><span class="refentrytitle">glBlendColor</span></span></a> is referred to as | |
96 | <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> | |
97 | ||
98 | <mml:mfenced open="(" close=")"> | |
99 | <mml:msub><mml:mi mathvariant="italic">R</mml:mi> | |
100 | <mml:mi mathvariant="italic">c</mml:mi> | |
101 | </mml:msub> | |
102 | <mml:msub><mml:mi mathvariant="italic">G</mml:mi> | |
103 | <mml:mi mathvariant="italic">c</mml:mi> | |
104 | </mml:msub> | |
105 | <mml:msub><mml:mi mathvariant="italic">B</mml:mi> | |
106 | <mml:mi mathvariant="italic">c</mml:mi> | |
107 | </mml:msub> | |
108 | <mml:msub><mml:mi mathvariant="italic">A</mml:mi> | |
109 | <mml:mi mathvariant="italic">c</mml:mi> | |
110 | </mml:msub> | |
111 | </mml:mfenced> | |
112 | </mml:math>. | |
113 | They are understood to have integer values between 0 and | |
114 | <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> | |
115 | ||
116 | <mml:mfenced open="(" close=")"> | |
117 | <mml:msub><mml:mi mathvariant="italic">k</mml:mi> | |
118 | <mml:mi mathvariant="italic">R</mml:mi> | |
119 | </mml:msub> | |
120 | <mml:msub><mml:mi mathvariant="italic">k</mml:mi> | |
121 | <mml:mi mathvariant="italic">G</mml:mi> | |
122 | </mml:msub> | |
123 | <mml:msub><mml:mi mathvariant="italic">k</mml:mi> | |
124 | <mml:mi mathvariant="italic">B</mml:mi> | |
125 | </mml:msub> | |
126 | <mml:msub><mml:mi mathvariant="italic">k</mml:mi> | |
127 | <mml:mi mathvariant="italic">A</mml:mi> | |
128 | </mml:msub> | |
129 | </mml:mfenced> | |
130 | </mml:math>, | |
131 | where | |
132 | </p><p> | |
133 | </p><p> | |
134 | <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> | |
135 | ||
136 | <mml:mrow> | |
137 | <mml:msub><mml:mi mathvariant="italic">k</mml:mi> | |
138 | <mml:mi mathvariant="italic">c</mml:mi> | |
139 | </mml:msub> | |
140 | <mml:mo>=</mml:mo> | |
141 | <mml:mrow> | |
142 | <mml:msup><mml:mn>2</mml:mn> | |
143 | <mml:mfenced open="" close=""> | |
144 | <mml:msub><mml:mi mathvariant="italic">m</mml:mi> | |
145 | <mml:mi mathvariant="italic">c</mml:mi> | |
146 | </mml:msub> | |
147 | </mml:mfenced> | |
148 | </mml:msup> | |
149 | <mml:mo>-</mml:mo> | |
150 | <mml:mn>1</mml:mn> | |
151 | </mml:mrow> | |
152 | </mml:mrow> | |
153 | </mml:math> | |
154 | </p><p> | |
155 | </p><p> | |
156 | and | |
157 | <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> | |
158 | ||
159 | <mml:mfenced open="(" close=")"> | |
160 | <mml:msub><mml:mi mathvariant="italic">m</mml:mi> | |
161 | <mml:mi mathvariant="italic">R</mml:mi> | |
162 | </mml:msub> | |
163 | <mml:msub><mml:mi mathvariant="italic">m</mml:mi> | |
164 | <mml:mi mathvariant="italic">G</mml:mi> | |
165 | </mml:msub> | |
166 | <mml:msub><mml:mi mathvariant="italic">m</mml:mi> | |
167 | <mml:mi mathvariant="italic">B</mml:mi> | |
168 | </mml:msub> | |
169 | <mml:msub><mml:mi mathvariant="italic">m</mml:mi> | |
170 | <mml:mi mathvariant="italic">A</mml:mi> | |
171 | </mml:msub> | |
172 | </mml:mfenced> | |
173 | </mml:math> | |
174 | is the number of red, | |
175 | green, | |
176 | blue, | |
177 | and alpha bitplanes. | |
178 | </p><p> | |
179 | Source and destination scale factors are referred to as | |
180 | <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> | |
181 | ||
182 | <mml:mfenced open="(" close=")"> | |
183 | <mml:msub><mml:mi mathvariant="italic">s</mml:mi> | |
184 | <mml:mi mathvariant="italic">R</mml:mi> | |
185 | </mml:msub> | |
186 | <mml:msub><mml:mi mathvariant="italic">s</mml:mi> | |
187 | <mml:mi mathvariant="italic">G</mml:mi> | |
188 | </mml:msub> | |
189 | <mml:msub><mml:mi mathvariant="italic">s</mml:mi> | |
190 | <mml:mi mathvariant="italic">B</mml:mi> | |
191 | </mml:msub> | |
192 | <mml:msub><mml:mi mathvariant="italic">s</mml:mi> | |
193 | <mml:mi mathvariant="italic">A</mml:mi> | |
194 | </mml:msub> | |
195 | </mml:mfenced> | |
196 | </mml:math> | |
197 | and | |
198 | <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> | |
199 | ||
200 | <mml:mfenced open="(" close=")"> | |
201 | <mml:msub><mml:mi mathvariant="italic">d</mml:mi> | |
202 | <mml:mi mathvariant="italic">R</mml:mi> | |
203 | </mml:msub> | |
204 | <mml:msub><mml:mi mathvariant="italic">d</mml:mi> | |
205 | <mml:mi mathvariant="italic">G</mml:mi> | |
206 | </mml:msub> | |
207 | <mml:msub><mml:mi mathvariant="italic">d</mml:mi> | |
208 | <mml:mi mathvariant="italic">B</mml:mi> | |
209 | </mml:msub> | |
210 | <mml:msub><mml:mi mathvariant="italic">d</mml:mi> | |
211 | <mml:mi mathvariant="italic">A</mml:mi> | |
212 | </mml:msub> | |
213 | </mml:mfenced> | |
214 | </mml:math>. | |
215 | The scale factors described in the table, | |
216 | denoted | |
217 | <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> | |
218 | ||
219 | <mml:mfenced open="(" close=")"> | |
220 | <mml:msub><mml:mi mathvariant="italic">f</mml:mi> | |
221 | <mml:mi mathvariant="italic">R</mml:mi> | |
222 | </mml:msub> | |
223 | <mml:msub><mml:mi mathvariant="italic">f</mml:mi> | |
224 | <mml:mi mathvariant="italic">G</mml:mi> | |
225 | </mml:msub> | |
226 | <mml:msub><mml:mi mathvariant="italic">f</mml:mi> | |
227 | <mml:mi mathvariant="italic">B</mml:mi> | |
228 | </mml:msub> | |
229 | <mml:msub><mml:mi mathvariant="italic">f</mml:mi> | |
230 | <mml:mi mathvariant="italic">A</mml:mi> | |
231 | </mml:msub> | |
232 | </mml:mfenced> | |
233 | </mml:math>, | |
234 | represent either source or destination factors. | |
235 | All scale factors have range | |
236 | <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> | |
237 | ||
238 | <mml:mfenced open="[" close="]"> | |
239 | <mml:mn>0</mml:mn> | |
240 | <mml:mn>1</mml:mn> | |
241 | </mml:mfenced> | |
242 | </mml:math>. | |
243 | </p><p> | |
244 | </p><div class="informaltable"><table border="1"><colgroup><col align="left" /><col align="left" /></colgroup><thead><tr><th align="left"><span class="bold"><strong> | |
245 | Parameter | |
246 | </strong></span></th><th align="left"><span class="bold"><strong> | |
247 | <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> | |
248 | ||
249 | <mml:mfenced open="(" close=")"> | |
250 | <mml:msub><mml:mi mathvariant="italic">f</mml:mi> | |
251 | <mml:mi mathvariant="italic">R</mml:mi> | |
252 | </mml:msub> | |
253 | <mml:msub><mml:mi mathvariant="italic">f</mml:mi> | |
254 | <mml:mi mathvariant="italic">G</mml:mi> | |
255 | </mml:msub> | |
256 | <mml:msub><mml:mi mathvariant="italic">f</mml:mi> | |
257 | <mml:mi mathvariant="italic">B</mml:mi> | |
258 | </mml:msub> | |
259 | <mml:msub><mml:mi mathvariant="italic">f</mml:mi> | |
260 | <mml:mi mathvariant="italic">A</mml:mi> | |
261 | </mml:msub> | |
262 | </mml:mfenced> | |
263 | </mml:math> | |
264 | </strong></span></th></tr></thead><tbody><tr><td align="left"> | |
265 | <code class="constant">GL_ZERO</code> | |
266 | </td><td align="left"> | |
267 | <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> | |
268 | ||
269 | <mml:mfenced open="(" close=")"> | |
270 | <mml:mn>0</mml:mn> | |
271 | <mml:mn>0</mml:mn> | |
272 | <mml:mn>0</mml:mn> | |
273 | <mml:mn>0</mml:mn> | |
274 | </mml:mfenced> | |
275 | </mml:math> | |
276 | </td></tr><tr><td align="left"> | |
277 | <code class="constant">GL_ONE</code> | |
278 | </td><td align="left"> | |
279 | <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> | |
280 | ||
281 | <mml:mfenced open="(" close=")"> | |
282 | <mml:mn>1</mml:mn> | |
283 | <mml:mn>1</mml:mn> | |
284 | <mml:mn>1</mml:mn> | |
285 | <mml:mn>1</mml:mn> | |
286 | </mml:mfenced> | |
287 | </mml:math> | |
288 | </td></tr><tr><td align="left"> | |
289 | <code class="constant">GL_SRC_COLOR</code> | |
290 | </td><td align="left"> | |
291 | <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> | |
292 | ||
293 | <mml:mfenced open="(" close=")"> | |
294 | <mml:mfrac> | |
295 | <mml:msub><mml:mi mathvariant="italic">R</mml:mi> | |
296 | <mml:mi mathvariant="italic">s</mml:mi> | |
297 | </mml:msub> | |
298 | <mml:msub><mml:mi mathvariant="italic">k</mml:mi> | |
299 | <mml:mi mathvariant="italic">R</mml:mi> | |
300 | </mml:msub> | |
301 | </mml:mfrac> | |
302 | <mml:mfrac> | |
303 | <mml:msub><mml:mi mathvariant="italic">G</mml:mi> | |
304 | <mml:mi mathvariant="italic">s</mml:mi> | |
305 | </mml:msub> | |
306 | <mml:msub><mml:mi mathvariant="italic">k</mml:mi> | |
307 | <mml:mi mathvariant="italic">G</mml:mi> | |
308 | </mml:msub> | |
309 | </mml:mfrac> | |
310 | <mml:mfrac> | |
311 | <mml:msub><mml:mi mathvariant="italic">B</mml:mi> | |
312 | <mml:mi mathvariant="italic">s</mml:mi> | |
313 | </mml:msub> | |
314 | <mml:msub><mml:mi mathvariant="italic">k</mml:mi> | |
315 | <mml:mi mathvariant="italic">B</mml:mi> | |
316 | </mml:msub> | |
317 | </mml:mfrac> | |
318 | <mml:mfrac> | |
319 | <mml:msub><mml:mi mathvariant="italic">A</mml:mi> | |
320 | <mml:mi mathvariant="italic">s</mml:mi> | |
321 | </mml:msub> | |
322 | <mml:msub><mml:mi mathvariant="italic">k</mml:mi> | |
323 | <mml:mi mathvariant="italic">A</mml:mi> | |
324 | </mml:msub> | |
325 | </mml:mfrac> | |
326 | </mml:mfenced> | |
327 | </mml:math> | |
328 | </td></tr><tr><td align="left"> | |
329 | <code class="constant">GL_ONE_MINUS_SRC_COLOR</code> | |
330 | </td><td align="left"> | |
331 | <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> | |
332 | ||
333 | <mml:mrow> | |
334 | <mml:mfenced open="(" close=")"> | |
335 | <mml:mn>1</mml:mn> | |
336 | <mml:mn>1</mml:mn> | |
337 | <mml:mn>1</mml:mn> | |
338 | <mml:mn>1</mml:mn> | |
339 | </mml:mfenced> | |
340 | <mml:mo>-</mml:mo> | |
341 | <mml:mfenced open="(" close=")"> | |
342 | <mml:mfrac> | |
343 | <mml:msub><mml:mi mathvariant="italic">R</mml:mi> | |
344 | <mml:mi mathvariant="italic">s</mml:mi> | |
345 | </mml:msub> | |
346 | <mml:msub><mml:mi mathvariant="italic">k</mml:mi> | |
347 | <mml:mi mathvariant="italic">R</mml:mi> | |
348 | </mml:msub> | |
349 | </mml:mfrac> | |
350 | <mml:mfrac> | |
351 | <mml:msub><mml:mi mathvariant="italic">G</mml:mi> | |
352 | <mml:mi mathvariant="italic">s</mml:mi> | |
353 | </mml:msub> | |
354 | <mml:msub><mml:mi mathvariant="italic">k</mml:mi> | |
355 | <mml:mi mathvariant="italic">G</mml:mi> | |
356 | </mml:msub> | |
357 | </mml:mfrac> | |
358 | <mml:mfrac> | |
359 | <mml:msub><mml:mi mathvariant="italic">B</mml:mi> | |
360 | <mml:mi mathvariant="italic">s</mml:mi> | |
361 | </mml:msub> | |
362 | <mml:msub><mml:mi mathvariant="italic">k</mml:mi> | |
363 | <mml:mi mathvariant="italic">B</mml:mi> | |
364 | </mml:msub> | |
365 | </mml:mfrac> | |
366 | <mml:mfrac> | |
367 | <mml:msub><mml:mi mathvariant="italic">A</mml:mi> | |
368 | <mml:mi mathvariant="italic">s</mml:mi> | |
369 | </mml:msub> | |
370 | <mml:msub><mml:mi mathvariant="italic">k</mml:mi> | |
371 | <mml:mi mathvariant="italic">A</mml:mi> | |
372 | </mml:msub> | |
373 | </mml:mfrac> | |
374 | </mml:mfenced> | |
375 | </mml:mrow> | |
376 | </mml:math> | |
377 | </td></tr><tr><td align="left"> | |
378 | <code class="constant">GL_DST_COLOR</code> | |
379 | </td><td align="left"> | |
380 | <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> | |
381 | ||
382 | <mml:mfenced open="(" close=")"> | |
383 | <mml:mfrac> | |
384 | <mml:msub><mml:mi mathvariant="italic">R</mml:mi> | |
385 | <mml:mi mathvariant="italic">d</mml:mi> | |
386 | </mml:msub> | |
387 | <mml:msub><mml:mi mathvariant="italic">k</mml:mi> | |
388 | <mml:mi mathvariant="italic">R</mml:mi> | |
389 | </mml:msub> | |
390 | </mml:mfrac> | |
391 | <mml:mfrac> | |
392 | <mml:msub><mml:mi mathvariant="italic">G</mml:mi> | |
393 | <mml:mi mathvariant="italic">d</mml:mi> | |
394 | </mml:msub> | |
395 | <mml:msub><mml:mi mathvariant="italic">k</mml:mi> | |
396 | <mml:mi mathvariant="italic">G</mml:mi> | |
397 | </mml:msub> | |
398 | </mml:mfrac> | |
399 | <mml:mfrac> | |
400 | <mml:msub><mml:mi mathvariant="italic">B</mml:mi> | |
401 | <mml:mi mathvariant="italic">d</mml:mi> | |
402 | </mml:msub> | |
403 | <mml:msub><mml:mi mathvariant="italic">k</mml:mi> | |
404 | <mml:mi mathvariant="italic">B</mml:mi> | |
405 | </mml:msub> | |
406 | </mml:mfrac> | |
407 | <mml:mfrac> | |
408 | <mml:msub><mml:mi mathvariant="italic">A</mml:mi> | |
409 | <mml:mi mathvariant="italic">d</mml:mi> | |
410 | </mml:msub> | |
411 | <mml:msub><mml:mi mathvariant="italic">k</mml:mi> | |
412 | <mml:mi mathvariant="italic">A</mml:mi> | |
413 | </mml:msub> | |
414 | </mml:mfrac> | |
415 | </mml:mfenced> | |
416 | </mml:math> | |
417 | </td></tr><tr><td align="left"> | |
418 | <code class="constant">GL_ONE_MINUS_DST_COLOR</code> | |
419 | </td><td align="left"> | |
420 | <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> | |
421 | ||
422 | <mml:mrow> | |
423 | <mml:mfenced open="(" close=")"> | |
424 | <mml:mn>1</mml:mn> | |
425 | <mml:mn>1</mml:mn> | |
426 | <mml:mn>1</mml:mn> | |
427 | <mml:mn>1</mml:mn> | |
428 | </mml:mfenced> | |
429 | <mml:mo>-</mml:mo> | |
430 | <mml:mfenced open="(" close=")"> | |
431 | <mml:mfrac> | |
432 | <mml:msub><mml:mi mathvariant="italic">R</mml:mi> | |
433 | <mml:mi mathvariant="italic">d</mml:mi> | |
434 | </mml:msub> | |
435 | <mml:msub><mml:mi mathvariant="italic">k</mml:mi> | |
436 | <mml:mi mathvariant="italic">R</mml:mi> | |
437 | </mml:msub> | |
438 | </mml:mfrac> | |
439 | <mml:mfrac> | |
440 | <mml:msub><mml:mi mathvariant="italic">G</mml:mi> | |
441 | <mml:mi mathvariant="italic">d</mml:mi> | |
442 | </mml:msub> | |
443 | <mml:msub><mml:mi mathvariant="italic">k</mml:mi> | |
444 | <mml:mi mathvariant="italic">G</mml:mi> | |
445 | </mml:msub> | |
446 | </mml:mfrac> | |
447 | <mml:mfrac> | |
448 | <mml:msub><mml:mi mathvariant="italic">B</mml:mi> | |
449 | <mml:mi mathvariant="italic">d</mml:mi> | |
450 | </mml:msub> | |
451 | <mml:msub><mml:mi mathvariant="italic">k</mml:mi> | |
452 | <mml:mi mathvariant="italic">B</mml:mi> | |
453 | </mml:msub> | |
454 | </mml:mfrac> | |
455 | <mml:mfrac> | |
456 | <mml:msub><mml:mi mathvariant="italic">A</mml:mi> | |
457 | <mml:mi mathvariant="italic">d</mml:mi> | |
458 | </mml:msub> | |
459 | <mml:msub><mml:mi mathvariant="italic">k</mml:mi> | |
460 | <mml:mi mathvariant="italic">A</mml:mi> | |
461 | </mml:msub> | |
462 | </mml:mfrac> | |
463 | </mml:mfenced> | |
464 | </mml:mrow> | |
465 | </mml:math> | |
466 | </td></tr><tr><td align="left"> | |
467 | <code class="constant">GL_SRC_ALPHA</code> | |
468 | </td><td align="left"> | |
469 | <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> | |
470 | ||
471 | <mml:mfenced open="(" close=")"> | |
472 | <mml:mfrac> | |
473 | <mml:msub><mml:mi mathvariant="italic">A</mml:mi> | |
474 | <mml:mi mathvariant="italic">s</mml:mi> | |
475 | </mml:msub> | |
476 | <mml:msub><mml:mi mathvariant="italic">k</mml:mi> | |
477 | <mml:mi mathvariant="italic">A</mml:mi> | |
478 | </mml:msub> | |
479 | </mml:mfrac> | |
480 | <mml:mfrac> | |
481 | <mml:msub><mml:mi mathvariant="italic">A</mml:mi> | |
482 | <mml:mi mathvariant="italic">s</mml:mi> | |
483 | </mml:msub> | |
484 | <mml:msub><mml:mi mathvariant="italic">k</mml:mi> | |
485 | <mml:mi mathvariant="italic">A</mml:mi> | |
486 | </mml:msub> | |
487 | </mml:mfrac> | |
488 | <mml:mfrac> | |
489 | <mml:msub><mml:mi mathvariant="italic">A</mml:mi> | |
490 | <mml:mi mathvariant="italic">s</mml:mi> | |
491 | </mml:msub> | |
492 | <mml:msub><mml:mi mathvariant="italic">k</mml:mi> | |
493 | <mml:mi mathvariant="italic">A</mml:mi> | |
494 | </mml:msub> | |
495 | </mml:mfrac> | |
496 | <mml:mfrac> | |
497 | <mml:msub><mml:mi mathvariant="italic">A</mml:mi> | |
498 | <mml:mi mathvariant="italic">s</mml:mi> | |
499 | </mml:msub> | |
500 | <mml:msub><mml:mi mathvariant="italic">k</mml:mi> | |
501 | <mml:mi mathvariant="italic">A</mml:mi> | |
502 | </mml:msub> | |
503 | </mml:mfrac> | |
504 | </mml:mfenced> | |
505 | </mml:math> | |
506 | </td></tr><tr><td align="left"> | |
507 | <code class="constant">GL_ONE_MINUS_SRC_ALPHA</code> | |
508 | </td><td align="left"> | |
509 | <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> | |
510 | ||
511 | <mml:mrow> | |
512 | <mml:mfenced open="(" close=")"> | |
513 | <mml:mn>1</mml:mn> | |
514 | <mml:mn>1</mml:mn> | |
515 | <mml:mn>1</mml:mn> | |
516 | <mml:mn>1</mml:mn> | |
517 | </mml:mfenced> | |
518 | <mml:mo>-</mml:mo> | |
519 | <mml:mfenced open="(" close=")"> | |
520 | <mml:mfrac> | |
521 | <mml:msub><mml:mi mathvariant="italic">A</mml:mi> | |
522 | <mml:mi mathvariant="italic">s</mml:mi> | |
523 | </mml:msub> | |
524 | <mml:msub><mml:mi mathvariant="italic">k</mml:mi> | |
525 | <mml:mi mathvariant="italic">A</mml:mi> | |
526 | </mml:msub> | |
527 | </mml:mfrac> | |
528 | <mml:mfrac> | |
529 | <mml:msub><mml:mi mathvariant="italic">A</mml:mi> | |
530 | <mml:mi mathvariant="italic">s</mml:mi> | |
531 | </mml:msub> | |
532 | <mml:msub><mml:mi mathvariant="italic">k</mml:mi> | |
533 | <mml:mi mathvariant="italic">A</mml:mi> | |
534 | </mml:msub> | |
535 | </mml:mfrac> | |
536 | <mml:mfrac> | |
537 | <mml:msub><mml:mi mathvariant="italic">A</mml:mi> | |
538 | <mml:mi mathvariant="italic">s</mml:mi> | |
539 | </mml:msub> | |
540 | <mml:msub><mml:mi mathvariant="italic">k</mml:mi> | |
541 | <mml:mi mathvariant="italic">A</mml:mi> | |
542 | </mml:msub> | |
543 | </mml:mfrac> | |
544 | <mml:mfrac> | |
545 | <mml:msub><mml:mi mathvariant="italic">A</mml:mi> | |
546 | <mml:mi mathvariant="italic">s</mml:mi> | |
547 | </mml:msub> | |
548 | <mml:msub><mml:mi mathvariant="italic">k</mml:mi> | |
549 | <mml:mi mathvariant="italic">A</mml:mi> | |
550 | </mml:msub> | |
551 | </mml:mfrac> | |
552 | </mml:mfenced> | |
553 | </mml:mrow> | |
554 | </mml:math> | |
555 | </td></tr><tr><td align="left"> | |
556 | <code class="constant">GL_DST_ALPHA</code> | |
557 | </td><td align="left"> | |
558 | <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> | |
559 | ||
560 | <mml:mfenced open="(" close=")"> | |
561 | <mml:mfrac> | |
562 | <mml:msub><mml:mi mathvariant="italic">A</mml:mi> | |
563 | <mml:mi mathvariant="italic">d</mml:mi> | |
564 | </mml:msub> | |
565 | <mml:msub><mml:mi mathvariant="italic">k</mml:mi> | |
566 | <mml:mi mathvariant="italic">A</mml:mi> | |
567 | </mml:msub> | |
568 | </mml:mfrac> | |
569 | <mml:mfrac> | |
570 | <mml:msub><mml:mi mathvariant="italic">A</mml:mi> | |
571 | <mml:mi mathvariant="italic">d</mml:mi> | |
572 | </mml:msub> | |
573 | <mml:msub><mml:mi mathvariant="italic">k</mml:mi> | |
574 | <mml:mi mathvariant="italic">A</mml:mi> | |
575 | </mml:msub> | |
576 | </mml:mfrac> | |
577 | <mml:mfrac> | |
578 | <mml:msub><mml:mi mathvariant="italic">A</mml:mi> | |
579 | <mml:mi mathvariant="italic">d</mml:mi> | |
580 | </mml:msub> | |
581 | <mml:msub><mml:mi mathvariant="italic">k</mml:mi> | |
582 | <mml:mi mathvariant="italic">A</mml:mi> | |
583 | </mml:msub> | |
584 | </mml:mfrac> | |
585 | <mml:mfrac> | |
586 | <mml:msub><mml:mi mathvariant="italic">A</mml:mi> | |
587 | <mml:mi mathvariant="italic">d</mml:mi> | |
588 | </mml:msub> | |
589 | <mml:msub><mml:mi mathvariant="italic">k</mml:mi> | |
590 | <mml:mi mathvariant="italic">A</mml:mi> | |
591 | </mml:msub> | |
592 | </mml:mfrac> | |
593 | </mml:mfenced> | |
594 | </mml:math> | |
595 | </td></tr><tr><td align="left"> | |
596 | <code class="constant">GL_ONE_MINUS_DST_ALPHA</code> | |
597 | </td><td align="left"> | |
598 | <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> | |
599 | ||
600 | <mml:mrow> | |
601 | <mml:mfenced open="(" close=")"> | |
602 | <mml:mn>1</mml:mn> | |
603 | <mml:mn>1</mml:mn> | |
604 | <mml:mn>1</mml:mn> | |
605 | <mml:mn>1</mml:mn> | |
606 | </mml:mfenced> | |
607 | <mml:mo>-</mml:mo> | |
608 | <mml:mfenced open="(" close=")"> | |
609 | <mml:mfrac> | |
610 | <mml:msub><mml:mi mathvariant="italic">A</mml:mi> | |
611 | <mml:mi mathvariant="italic">d</mml:mi> | |
612 | </mml:msub> | |
613 | <mml:msub><mml:mi mathvariant="italic">k</mml:mi> | |
614 | <mml:mi mathvariant="italic">A</mml:mi> | |
615 | </mml:msub> | |
616 | </mml:mfrac> | |
617 | <mml:mfrac> | |
618 | <mml:msub><mml:mi mathvariant="italic">A</mml:mi> | |
619 | <mml:mi mathvariant="italic">d</mml:mi> | |
620 | </mml:msub> | |
621 | <mml:msub><mml:mi mathvariant="italic">k</mml:mi> | |
622 | <mml:mi mathvariant="italic">A</mml:mi> | |
623 | </mml:msub> | |
624 | </mml:mfrac> | |
625 | <mml:mfrac> | |
626 | <mml:msub><mml:mi mathvariant="italic">A</mml:mi> | |
627 | <mml:mi mathvariant="italic">d</mml:mi> | |
628 | </mml:msub> | |
629 | <mml:msub><mml:mi mathvariant="italic">k</mml:mi> | |
630 | <mml:mi mathvariant="italic">A</mml:mi> | |
631 | </mml:msub> | |
632 | </mml:mfrac> | |
633 | <mml:mfrac> | |
634 | <mml:msub><mml:mi mathvariant="italic">A</mml:mi> | |
635 | <mml:mi mathvariant="italic">d</mml:mi> | |
636 | </mml:msub> | |
637 | <mml:msub><mml:mi mathvariant="italic">k</mml:mi> | |
638 | <mml:mi mathvariant="italic">A</mml:mi> | |
639 | </mml:msub> | |
640 | </mml:mfrac> | |
641 | </mml:mfenced> | |
642 | </mml:mrow> | |
643 | </mml:math> | |
644 | </td></tr><tr><td align="left"> | |
645 | <code class="constant">GL_CONSTANT_COLOR</code> | |
646 | </td><td align="left"> | |
647 | <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> | |
648 | ||
649 | <mml:mfenced open="(" close=")"> | |
650 | <mml:msub><mml:mi mathvariant="italic">R</mml:mi> | |
651 | <mml:mi mathvariant="italic">c</mml:mi> | |
652 | </mml:msub> | |
653 | <mml:msub><mml:mi mathvariant="italic">G</mml:mi> | |
654 | <mml:mi mathvariant="italic">c</mml:mi> | |
655 | </mml:msub> | |
656 | <mml:msub><mml:mi mathvariant="italic">B</mml:mi> | |
657 | <mml:mi mathvariant="italic">c</mml:mi> | |
658 | </mml:msub> | |
659 | <mml:msub><mml:mi mathvariant="italic">A</mml:mi> | |
660 | <mml:mi mathvariant="italic">c</mml:mi> | |
661 | </mml:msub> | |
662 | </mml:mfenced> | |
663 | </mml:math> | |
664 | </td></tr><tr><td align="left"> | |
665 | <code class="constant">GL_ONE_MINUS_CONSTANT_COLOR</code> | |
666 | </td><td align="left"> | |
667 | <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> | |
668 | ||
669 | <mml:mrow> | |
670 | <mml:mfenced open="(" close=")"> | |
671 | <mml:mn>1</mml:mn> | |
672 | <mml:mn>1</mml:mn> | |
673 | <mml:mn>1</mml:mn> | |
674 | <mml:mn>1</mml:mn> | |
675 | </mml:mfenced> | |
676 | <mml:mo>-</mml:mo> | |
677 | <mml:mfenced open="(" close=")"> | |
678 | <mml:msub><mml:mi mathvariant="italic">R</mml:mi> | |
679 | <mml:mi mathvariant="italic">c</mml:mi> | |
680 | </mml:msub> | |
681 | <mml:msub><mml:mi mathvariant="italic">G</mml:mi> | |
682 | <mml:mi mathvariant="italic">c</mml:mi> | |
683 | </mml:msub> | |
684 | <mml:msub><mml:mi mathvariant="italic">B</mml:mi> | |
685 | <mml:mi mathvariant="italic">c</mml:mi> | |
686 | </mml:msub> | |
687 | <mml:msub><mml:mi mathvariant="italic">A</mml:mi> | |
688 | <mml:mi mathvariant="italic">c</mml:mi> | |
689 | </mml:msub> | |
690 | </mml:mfenced> | |
691 | </mml:mrow> | |
692 | </mml:math> | |
693 | </td></tr><tr><td align="left"> | |
694 | <code class="constant">GL_CONSTANT_ALPHA</code> | |
695 | </td><td align="left"> | |
696 | <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> | |
697 | ||
698 | <mml:mfenced open="(" close=")"> | |
699 | <mml:msub><mml:mi mathvariant="italic">A</mml:mi> | |
700 | <mml:mi mathvariant="italic">c</mml:mi> | |
701 | </mml:msub> | |
702 | <mml:msub><mml:mi mathvariant="italic">A</mml:mi> | |
703 | <mml:mi mathvariant="italic">c</mml:mi> | |
704 | </mml:msub> | |
705 | <mml:msub><mml:mi mathvariant="italic">A</mml:mi> | |
706 | <mml:mi mathvariant="italic">c</mml:mi> | |
707 | </mml:msub> | |
708 | <mml:msub><mml:mi mathvariant="italic">A</mml:mi> | |
709 | <mml:mi mathvariant="italic">c</mml:mi> | |
710 | </mml:msub> | |
711 | </mml:mfenced> | |
712 | </mml:math> | |
713 | </td></tr><tr><td align="left"> | |
714 | <code class="constant">GL_ONE_MINUS_CONSTANT_ALPHA</code> | |
715 | </td><td align="left"> | |
716 | <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> | |
717 | ||
718 | <mml:mrow> | |
719 | <mml:mfenced open="(" close=")"> | |
720 | <mml:mn>1</mml:mn> | |
721 | <mml:mn>1</mml:mn> | |
722 | <mml:mn>1</mml:mn> | |
723 | <mml:mn>1</mml:mn> | |
724 | </mml:mfenced> | |
725 | <mml:mo>-</mml:mo> | |
726 | <mml:mfenced open="(" close=")"> | |
727 | <mml:msub><mml:mi mathvariant="italic">A</mml:mi> | |
728 | <mml:mi mathvariant="italic">c</mml:mi> | |
729 | </mml:msub> | |
730 | <mml:msub><mml:mi mathvariant="italic">A</mml:mi> | |
731 | <mml:mi mathvariant="italic">c</mml:mi> | |
732 | </mml:msub> | |
733 | <mml:msub><mml:mi mathvariant="italic">A</mml:mi> | |
734 | <mml:mi mathvariant="italic">c</mml:mi> | |
735 | </mml:msub> | |
736 | <mml:msub><mml:mi mathvariant="italic">A</mml:mi> | |
737 | <mml:mi mathvariant="italic">c</mml:mi> | |
738 | </mml:msub> | |
739 | </mml:mfenced> | |
740 | </mml:mrow> | |
741 | </mml:math> | |
742 | </td></tr><tr><td align="left"> | |
743 | <code class="constant">GL_SRC_ALPHA_SATURATE</code> | |
744 | </td><td align="left"> | |
745 | <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> | |
746 | ||
747 | <mml:mfenced open="(" close=")"> | |
748 | <mml:mi mathvariant="italic">i</mml:mi> | |
749 | <mml:mi mathvariant="italic">i</mml:mi> | |
750 | <mml:mi mathvariant="italic">i</mml:mi> | |
751 | <mml:mn>1</mml:mn> | |
752 | </mml:mfenced> | |
753 | </mml:math> | |
754 | </td></tr></tbody></table></div><p> | |
755 | In the table, | |
756 | </p><p> | |
757 | </p><p> | |
758 | <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> | |
759 | ||
760 | <mml:mrow> | |
761 | <mml:mi mathvariant="italic">i</mml:mi> | |
762 | <mml:mo>=</mml:mo> | |
763 | <mml:mfrac> | |
764 | <mml:mrow> | |
765 | <mml:mi mathvariant="italic">min</mml:mi> | |
766 | <mml:mo></mml:mo> | |
767 | <mml:mfenced open="(" close=")"> | |
768 | <mml:msub><mml:mi mathvariant="italic">A</mml:mi> | |
769 | <mml:mi mathvariant="italic">s</mml:mi> | |
770 | </mml:msub> | |
771 | <mml:mrow> | |
772 | <mml:msub><mml:mi mathvariant="italic">k</mml:mi> | |
773 | <mml:mi mathvariant="italic">A</mml:mi> | |
774 | </mml:msub> | |
775 | <mml:mo>-</mml:mo> | |
776 | <mml:msub><mml:mi mathvariant="italic">A</mml:mi> | |
777 | <mml:mi mathvariant="italic">d</mml:mi> | |
778 | </mml:msub> | |
779 | </mml:mrow> | |
780 | </mml:mfenced> | |
781 | </mml:mrow> | |
782 | <mml:msub><mml:mi mathvariant="italic">k</mml:mi> | |
783 | <mml:mi mathvariant="italic">A</mml:mi> | |
784 | </mml:msub> | |
785 | </mml:mfrac> | |
786 | </mml:mrow> | |
787 | </mml:math> | |
788 | </p><p> | |
789 | </p><p> | |
790 | To determine the blended RGBA values of a pixel when drawing in RGBA mode, | |
791 | the system uses the following equations: | |
792 | </p><p> | |
793 | </p><p> | |
794 | <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> | |
795 | ||
796 | <mml:mrow> | |
797 | <mml:msub><mml:mi mathvariant="italic">R</mml:mi> | |
798 | <mml:mi mathvariant="italic">d</mml:mi> | |
799 | </mml:msub> | |
800 | <mml:mo>=</mml:mo> | |
801 | <mml:mrow> | |
802 | <mml:mi mathvariant="italic">min</mml:mi> | |
803 | <mml:mo></mml:mo> | |
804 | <mml:mfenced open="(" close=")"> | |
805 | <mml:msub><mml:mi mathvariant="italic">k</mml:mi> | |
806 | <mml:mi mathvariant="italic">R</mml:mi> | |
807 | </mml:msub> | |
808 | <mml:mrow> | |
809 | <mml:msub><mml:mi mathvariant="italic">R</mml:mi> | |
810 | <mml:mi mathvariant="italic">s</mml:mi> | |
811 | </mml:msub> | |
812 | <mml:mo></mml:mo> | |
813 | <mml:msub><mml:mi mathvariant="italic">s</mml:mi> | |
814 | <mml:mi mathvariant="italic">R</mml:mi> | |
815 | </mml:msub> | |
816 | <mml:mo>+</mml:mo> | |
817 | <mml:msub><mml:mi mathvariant="italic">R</mml:mi> | |
818 | <mml:mi mathvariant="italic">d</mml:mi> | |
819 | </mml:msub> | |
820 | <mml:mo></mml:mo> | |
821 | <mml:msub><mml:mi mathvariant="italic">d</mml:mi> | |
822 | <mml:mi mathvariant="italic">R</mml:mi> | |
823 | </mml:msub> | |
824 | </mml:mrow> | |
825 | </mml:mfenced> | |
826 | </mml:mrow> | |
827 | </mml:mrow> | |
828 | </mml:math> | |
829 | <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> | |
830 | ||
831 | <mml:mrow> | |
832 | <mml:msub><mml:mi mathvariant="italic">G</mml:mi> | |
833 | <mml:mi mathvariant="italic">d</mml:mi> | |
834 | </mml:msub> | |
835 | <mml:mo>=</mml:mo> | |
836 | <mml:mrow> | |
837 | <mml:mi mathvariant="italic">min</mml:mi> | |
838 | <mml:mo></mml:mo> | |
839 | <mml:mfenced open="(" close=")"> | |
840 | <mml:msub><mml:mi mathvariant="italic">k</mml:mi> | |
841 | <mml:mi mathvariant="italic">G</mml:mi> | |
842 | </mml:msub> | |
843 | <mml:mrow> | |
844 | <mml:msub><mml:mi mathvariant="italic">G</mml:mi> | |
845 | <mml:mi mathvariant="italic">s</mml:mi> | |
846 | </mml:msub> | |
847 | <mml:mo></mml:mo> | |
848 | <mml:msub><mml:mi mathvariant="italic">s</mml:mi> | |
849 | <mml:mi mathvariant="italic">G</mml:mi> | |
850 | </mml:msub> | |
851 | <mml:mo>+</mml:mo> | |
852 | <mml:msub><mml:mi mathvariant="italic">G</mml:mi> | |
853 | <mml:mi mathvariant="italic">d</mml:mi> | |
854 | </mml:msub> | |
855 | <mml:mo></mml:mo> | |
856 | <mml:msub><mml:mi mathvariant="italic">d</mml:mi> | |
857 | <mml:mi mathvariant="italic">G</mml:mi> | |
858 | </mml:msub> | |
859 | </mml:mrow> | |
860 | </mml:mfenced> | |
861 | </mml:mrow> | |
862 | </mml:mrow> | |
863 | </mml:math> | |
864 | <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> | |
865 | ||
866 | <mml:mrow> | |
867 | <mml:msub><mml:mi mathvariant="italic">B</mml:mi> | |
868 | <mml:mi mathvariant="italic">d</mml:mi> | |
869 | </mml:msub> | |
870 | <mml:mo>=</mml:mo> | |
871 | <mml:mrow> | |
872 | <mml:mi mathvariant="italic">min</mml:mi> | |
873 | <mml:mo></mml:mo> | |
874 | <mml:mfenced open="(" close=")"> | |
875 | <mml:msub><mml:mi mathvariant="italic">k</mml:mi> | |
876 | <mml:mi mathvariant="italic">B</mml:mi> | |
877 | </mml:msub> | |
878 | <mml:mrow> | |
879 | <mml:msub><mml:mi mathvariant="italic">B</mml:mi> | |
880 | <mml:mi mathvariant="italic">s</mml:mi> | |
881 | </mml:msub> | |
882 | <mml:mo></mml:mo> | |
883 | <mml:msub><mml:mi mathvariant="italic">s</mml:mi> | |
884 | <mml:mi mathvariant="italic">B</mml:mi> | |
885 | </mml:msub> | |
886 | <mml:mo>+</mml:mo> | |
887 | <mml:msub><mml:mi mathvariant="italic">B</mml:mi> | |
888 | <mml:mi mathvariant="italic">d</mml:mi> | |
889 | </mml:msub> | |
890 | <mml:mo></mml:mo> | |
891 | <mml:msub><mml:mi mathvariant="italic">d</mml:mi> | |
892 | <mml:mi mathvariant="italic">B</mml:mi> | |
893 | </mml:msub> | |
894 | </mml:mrow> | |
895 | </mml:mfenced> | |
896 | </mml:mrow> | |
897 | </mml:mrow> | |
898 | </mml:math> | |
899 | <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> | |
900 | ||
901 | <mml:mrow> | |
902 | <mml:msub><mml:mi mathvariant="italic">A</mml:mi> | |
903 | <mml:mi mathvariant="italic">d</mml:mi> | |
904 | </mml:msub> | |
905 | <mml:mo>=</mml:mo> | |
906 | <mml:mrow> | |
907 | <mml:mi mathvariant="italic">min</mml:mi> | |
908 | <mml:mo></mml:mo> | |
909 | <mml:mfenced open="(" close=")"> | |
910 | <mml:msub><mml:mi mathvariant="italic">k</mml:mi> | |
911 | <mml:mi mathvariant="italic">A</mml:mi> | |
912 | </mml:msub> | |
913 | <mml:mrow> | |
914 | <mml:msub><mml:mi mathvariant="italic">A</mml:mi> | |
915 | <mml:mi mathvariant="italic">s</mml:mi> | |
916 | </mml:msub> | |
917 | <mml:mo></mml:mo> | |
918 | <mml:msub><mml:mi mathvariant="italic">s</mml:mi> | |
919 | <mml:mi mathvariant="italic">A</mml:mi> | |
920 | </mml:msub> | |
921 | <mml:mo>+</mml:mo> | |
922 | <mml:msub><mml:mi mathvariant="italic">A</mml:mi> | |
923 | <mml:mi mathvariant="italic">d</mml:mi> | |
924 | </mml:msub> | |
925 | <mml:mo></mml:mo> | |
926 | <mml:msub><mml:mi mathvariant="italic">d</mml:mi> | |
927 | <mml:mi mathvariant="italic">A</mml:mi> | |
928 | </mml:msub> | |
929 | </mml:mrow> | |
930 | </mml:mfenced> | |
931 | </mml:mrow> | |
932 | </mml:mrow> | |
933 | </mml:math> | |
934 | </p><p> | |
935 | </p><p> | |
936 | Despite the apparent precision of the above equations, | |
937 | blending arithmetic is not exactly specified, | |
938 | because blending operates with imprecise integer color values. | |
939 | However, | |
940 | a blend factor that should be equal to 1 | |
941 | is guaranteed not to modify its multiplicand, | |
942 | and a blend factor equal to 0 reduces its multiplicand to 0. | |
943 | For example, | |
944 | when <em class="parameter"><code>sfactor</code></em> is <code class="constant">GL_SRC_ALPHA</code>, | |
945 | <em class="parameter"><code>dfactor</code></em> is <code class="constant">GL_ONE_MINUS_SRC_ALPHA</code>, | |
946 | and | |
947 | <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> | |
948 | ||
949 | <mml:msub><mml:mi mathvariant="italic">A</mml:mi> | |
950 | <mml:mi mathvariant="italic">s</mml:mi> | |
951 | </mml:msub> | |
952 | </mml:math> | |
953 | is equal to | |
954 | <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> | |
955 | ||
956 | <mml:msub><mml:mi mathvariant="italic">k</mml:mi> | |
957 | <mml:mi mathvariant="italic">A</mml:mi> | |
958 | </mml:msub> | |
959 | </mml:math>, | |
960 | the equations reduce to simple replacement: | |
961 | </p><p> | |
962 | </p><p> | |
963 | <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> | |
964 | ||
965 | <mml:mrow> | |
966 | <mml:msub><mml:mi mathvariant="italic">R</mml:mi> | |
967 | <mml:mi mathvariant="italic">d</mml:mi> | |
968 | </mml:msub> | |
969 | <mml:mo>=</mml:mo> | |
970 | <mml:msub><mml:mi mathvariant="italic">R</mml:mi> | |
971 | <mml:mi mathvariant="italic">s</mml:mi> | |
972 | </mml:msub> | |
973 | </mml:mrow> | |
974 | </mml:math> | |
975 | <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> | |
976 | ||
977 | <mml:mrow> | |
978 | <mml:msub><mml:mi mathvariant="italic">G</mml:mi> | |
979 | <mml:mi mathvariant="italic">d</mml:mi> | |
980 | </mml:msub> | |
981 | <mml:mo>=</mml:mo> | |
982 | <mml:msub><mml:mi mathvariant="italic">G</mml:mi> | |
983 | <mml:mi mathvariant="italic">s</mml:mi> | |
984 | </mml:msub> | |
985 | </mml:mrow> | |
986 | </mml:math> | |
987 | <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> | |
988 | ||
989 | <mml:mrow> | |
990 | <mml:msub><mml:mi mathvariant="italic">B</mml:mi> | |
991 | <mml:mi mathvariant="italic">d</mml:mi> | |
992 | </mml:msub> | |
993 | <mml:mo>=</mml:mo> | |
994 | <mml:msub><mml:mi mathvariant="italic">B</mml:mi> | |
995 | <mml:mi mathvariant="italic">s</mml:mi> | |
996 | </mml:msub> | |
997 | </mml:mrow> | |
998 | </mml:math> | |
999 | <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> | |
1000 | ||
1001 | <mml:mrow> | |
1002 | <mml:msub><mml:mi mathvariant="italic">A</mml:mi> | |
1003 | <mml:mi mathvariant="italic">d</mml:mi> | |
1004 | </mml:msub> | |
1005 | <mml:mo>=</mml:mo> | |
1006 | <mml:msub><mml:mi mathvariant="italic">A</mml:mi> | |
1007 | <mml:mi mathvariant="italic">s</mml:mi> | |
1008 | </mml:msub> | |
1009 | </mml:mrow> | |
1010 | </mml:math> | |
1011 | </p><p> | |
1012 | </p><p> | |
1013 | </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="examples"></a><h2>Examples</h2><p> | |
1014 | </p><p> | |
1015 | Transparency is best implemented using blend function | |
1016 | (<code class="constant">GL_SRC_ALPHA</code>, <code class="constant">GL_ONE_MINUS_SRC_ALPHA</code>) | |
1017 | with primitives sorted from farthest to nearest. | |
1018 | Note that this transparency calculation does not require | |
1019 | the presence of alpha bitplanes in the frame buffer. | |
1020 | </p><p> | |
1021 | Blend function | |
1022 | (<code class="constant">GL_SRC_ALPHA</code>, <code class="constant">GL_ONE_MINUS_SRC_ALPHA</code>) | |
1023 | is also useful for rendering antialiased points and lines | |
1024 | in arbitrary order. | |
1025 | </p><p> | |
1026 | Polygon antialiasing is optimized using blend function | |
1027 | (<code class="constant">GL_SRC_ALPHA_SATURATE</code>, <code class="constant">GL_ONE</code>) | |
1028 | with polygons sorted from nearest to farthest. | |
1029 | (See the <a class="citerefentry" href="glEnable.xml"><span class="citerefentry"><span class="refentrytitle">glEnable</span></span></a>, <a class="citerefentry" href="glDisable.xml"><span class="citerefentry"><span class="refentrytitle">glDisable</span></span></a> reference page and the | |
1030 | <code class="constant">GL_POLYGON_SMOOTH</code> argument for information on polygon antialiasing.) | |
1031 | Destination alpha bitplanes, | |
1032 | which must be present for this blend function to operate correctly, | |
1033 | store the accumulated coverage. | |
1034 | </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="notes"></a><h2>Notes</h2><p> | |
1035 | Incoming (source) alpha is correctly thought of as a material opacity, | |
1036 | ranging from 1.0 | |
1037 | (<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> | |
1038 | ||
1039 | <mml:msub><mml:mi mathvariant="italic">K</mml:mi> | |
1040 | <mml:mi mathvariant="italic">A</mml:mi> | |
1041 | </mml:msub> | |
1042 | </mml:math>), | |
1043 | representing complete opacity, | |
1044 | to 0.0 (0), representing complete | |
1045 | transparency. | |
1046 | </p><p> | |
1047 | When more than one color buffer is enabled for drawing, | |
1048 | the GL performs blending separately for each enabled buffer, | |
1049 | using the contents of that buffer for destination color. | |
1050 | (See <a class="citerefentry" href="glDrawBuffer.xml"><span class="citerefentry"><span class="refentrytitle">glDrawBuffer</span></span></a>.) | |
1051 | </p><p> | |
1052 | Blending affects only RGBA rendering. | |
1053 | It is ignored by color index renderers. | |
1054 | </p><p> | |
1055 | <code class="constant">GL_CONSTANT_COLOR</code>, <code class="constant">GL_ONE_MINUS_CONSTANT_COLOR</code>, | |
1056 | <code class="constant">GL_CONSTANT_ALPHA</code>, <code class="constant">GL_ONE_MINUS_CONSTANT_ALPHA</code> are available only | |
1057 | if the GL version is 1.4 or greater or if the <code class="code">ARB_imaging</code> is | |
1058 | supported by your implementation. | |
1059 | </p><p> | |
1060 | <code class="constant">GL_SRC_COLOR</code> and <code class="constant">GL_ONE_MINUS_SRC_COLOR</code> are valid only for | |
1061 | <em class="parameter"><code>sfactor</code></em> if the GL version is 1.4 or greater. | |
1062 | </p><p> | |
1063 | <code class="constant">GL_DST_COLOR</code> and <code class="constant">GL_ONE_MINUS_DST_COLOR</code> are valid only for | |
1064 | <em class="parameter"><code>dfactor</code></em> if the GL version is 1.4 or greater. | |
1065 | </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="errors"></a><h2>Errors</h2><p> | |
1066 | <code class="constant">GL_INVALID_ENUM</code> is generated if either <em class="parameter"><code>sfactor</code></em> or <em class="parameter"><code>dfactor</code></em> is not an | |
1067 | accepted value. | |
1068 | </p><p> | |
1069 | <code class="constant">GL_INVALID_OPERATION</code> is generated if <code class="function">glBlendFunc</code> | |
1070 | is executed between the execution of <a class="citerefentry" href="glBegin.xml"><span class="citerefentry"><span class="refentrytitle">glBegin</span></span></a> | |
1071 | and the corresponding execution of <a class="citerefentry" href="glEnd.xml"><span class="citerefentry"><span class="refentrytitle">glEnd</span></span></a>. | |
1072 | </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="associatedgets"></a><h2>Associated Gets</h2><p> | |
1073 | <a class="citerefentry" href="glGet.xml"><span class="citerefentry"><span class="refentrytitle">glGet</span></span></a> with argument <code class="constant">GL_BLEND_SRC</code> | |
1074 | </p><p> | |
1075 | <a class="citerefentry" href="glGet.xml"><span class="citerefentry"><span class="refentrytitle">glGet</span></span></a> with argument <code class="constant">GL_BLEND_DST</code> | |
1076 | </p><p> | |
1077 | <a class="citerefentry" href="glIsEnabled.xml"><span class="citerefentry"><span class="refentrytitle">glIsEnabled</span></span></a> with argument <code class="constant">GL_BLEND</code> | |
1078 | </p><p> | |
1079 | </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="seealso"></a><h2>See Also</h2><p> | |
1080 | <a class="citerefentry" href="glAlphaFunc.xml"><span class="citerefentry"><span class="refentrytitle">glAlphaFunc</span></span></a>, | |
1081 | <a class="citerefentry" href="glBlendColor.xml"><span class="citerefentry"><span class="refentrytitle">glBlendColor</span></span></a>, | |
1082 | <a class="citerefentry" href="glBlendEquation.xml"><span class="citerefentry"><span class="refentrytitle">glBlendEquation</span></span></a>, | |
1083 | <a class="citerefentry" href="glBlendFuncSeparate.xml"><span class="citerefentry"><span class="refentrytitle">glBlendFuncSeparate</span></span></a>, | |
1084 | <a class="citerefentry" href="glClear.xml"><span class="citerefentry"><span class="refentrytitle">glClear</span></span></a>, | |
1085 | <a class="citerefentry" href="glDrawBuffer.xml"><span class="citerefentry"><span class="refentrytitle">glDrawBuffer</span></span></a>, | |
1086 | <a class="citerefentry" href="glEnable.xml"><span class="citerefentry"><span class="refentrytitle">glEnable</span></span></a>, | |
1087 | <a class="citerefentry" href="glLogicOp.xml"><span class="citerefentry"><span class="refentrytitle">glLogicOp</span></span></a>, | |
1088 | <a class="citerefentry" href="glStencilFunc.xml"><span class="citerefentry"><span class="refentrytitle">glStencilFunc</span></span></a> | |
1089 | ||
1090 | </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="Copyright"></a><h2>Copyright</h2><p> | |
1091 | Copyright <span class="trademark"></span>© 1991-2006 | |
1092 | Silicon Graphics, Inc. This document is licensed under the SGI | |
1093 | Free Software B License. For details, see | |
1094 | <a class="ulink" href="http://oss.sgi.com/projects/FreeB/" target="_top">http://oss.sgi.com/projects/FreeB/</a>. | |
1095 | </p></div></div></body></html> |