1GLXCHOOSEVISUAL() GLXCHOOSEVISUAL()
2
6 glXChooseVisual - return a visual that matches specified attributes
7
10 XVisualInfo* glXChooseVisual( Display *dpy,
11 int screen,
12 int *attribList )
13 delim $$
15
17 dpy Specifies the connection to the X server.
18 screen Specifies the screen number.
20 attribList Specifies a list of boolean attributes and integer
22 attribute/value pairs. The last attribute must be None.
23
25 glXChooseVisual returns a pointer to an XVisualInfo structure describ‐
26 ing the visual that best meets a minimum specification. The boolean
27 GLX attributes of the visual that is returned will match the specified
28 values, and the integer GLX attributes will meet or exceed the speci‐
29 fied minimum values. If all other attributes are equivalent, then
30 TrueColor and PseudoColor visuals have priority over DirectColor and
31 StaticColor visuals, respectively. If no conforming visual exists,
32 NULL is returned. To free the data returned by this function, use
33 XFree.
34 All boolean GLX attributes default to False except GLX_USE_GL, which
36 defaults to True. All integer GLX attributes default to zero. Default
37 specifications are superseded by attributes included in attribList.
38 Boolean attributes included in attribList are understood to be True.
39 Integer attributes and enumerated type attributes are followed immedi‐
40 ately by the corresponding desired or minimum value. The list must be
41 terminated with None.
42 The interpretations of the various GLX visual attributes are as fol‐
44 lows:
45 GLX_USE_GL Ignored. Only visuals that can be rendered with
47 GLX are considered.
48 GLX_BUFFER_SIZE Must be followed by a nonnegative integer that
50 indicates the desired color index buffer size.
51 The smallest index buffer of at least the speci‐
52 fied size is preferred. Ignored if GLX_RGBA is
53 asserted.
54 GLX_LEVEL Must be followed by an integer buffer-level spec‐
56 ification. This specification is honored
57 exactly. Buffer level zero corresponds to the
58 main frame buffer of the display. Buffer level
59 one is the first overlay frame buffer, level two
60 the second overlay frame buffer, and so on. Neg‐
61 ative buffer levels correspond to underlay frame
62 buffers.
63 GLX_RGBA If present, only TrueColor and DirectColor visu‐
65 als are considered. Otherwise, only PseudoColor
66 and StaticColor visuals are considered.
67 GLX_DOUBLEBUFFER If present, only double-buffered visuals are con‐
69 sidered. Otherwise, only single-buffered visu‐
70 als are considered.
71 GLX_STEREO If present, only stereo visuals are considered.
73 Otherwise, only monoscopic visuals are consid‐
74 ered.
75 GLX_AUX_BUFFERS Must be followed by a nonnegative integer that
77 indicates the desired number of auxiliary buf‐
78 fers. Visuals with the smallest number of aux‐
79 iliary buffers that meets or exceeds the speci‐
80 fied number are preferred.
81 GLX_RED_SIZE Must be followed by a nonnegative minimum size
83 specification. If this value is zero, the small‐
84 est available red buffer is preferred. Other‐
85 wise, the largest available red buffer of at
86 least the minimum size is preferred.
87 GLX_GREEN_SIZE Must be followed by a nonnegative minimum size
89 specification. If this value is zero, the small‐
90 est available green buffer is preferred. Other‐
91 wise, the largest available green buffer of at
92 least the minimum size is preferred.
93 GLX_BLUE_SIZE Must be followed by a nonnegative minimum size
95 specification. If this value is zero, the small‐
96 est available blue buffer is preferred. Other‐
97 wise, the largest available blue buffer of at
98 least the minimum size is preferred.
99 GLX_ALPHA_SIZE Must be followed by a nonnegative minimum size
101 specification. If this value is zero, the small‐
102 est available alpha buffer is preferred. Other‐
103 wise, the largest available alpha buffer of at
104 least the minimum size is preferred.
105 GLX_DEPTH_SIZE Must be followed by a nonnegative minimum size
107 specification. If this value is zero, visuals
108 with no depth buffer are preferred. Otherwise,
109 the largest available depth buffer of at least
110 the minimum size is preferred.
111 GLX_STENCIL_SIZE Must be followed by a nonnegative integer that
113 indicates the desired number of stencil bit‐
114 planes. The smallest stencil buffer of at least
115 the specified size is preferred. If the desired
116 value is zero, visuals with no stencil buffer are
117 preferred.
118 GLX_ACCUM_RED_SIZE Must be followed by a nonnegative minimum size
120 specification. If this value is zero, visuals
121 with no red accumulation buffer are preferred.
122 Otherwise, the largest possible red accumulation
123 buffer of at least the minimum size is preferred.
124 GLX_ACCUM_GREEN_SIZE Must be followed by a nonnegative minimum size
126 specification. If this value is zero, visuals
127 with no green accumulation buffer are preferred.
128 Otherwise, the largest possible green accumula‐
129 tion buffer of at least the minimum size is pre‐
130 ferred.
131 GLX_ACCUM_BLUE_SIZE Must be followed by a nonnegative minimum size
133 specification. If this value is zero, visuals
134 with no blue accumulation buffer are preferred.
135 Otherwise, the largest possible blue accumulation
136 buffer of at least the minimum size is preferred.
137 GLX_ACCUM_ALPHA_SIZE Must be followed by a nonnegative minimum size
139 specification. If this value is zero, visuals
140 with no alpha accumulation buffer are preferred.
141 Otherwise, the largest possible alpha accumula‐
142 tion buffer of at least the minimum size is pre‐
143 ferred.
144
146 attribList =
147 {GLX_RGBA, GLX_RED_SIZE, 4, GLX_GREEN_SIZE, 4,
148 GLX_BLUE_SIZE, 4, None};
149 Specifies a single-buffered RGB visual in the normal frame buffer, not
151 an overlay or underlay buffer. The returned visual supports at least
152 four bits each of red, green, and blue, and possibly no bits of alpha.
153 It does not support color index mode, double-buffering, or stereo dis‐
154 play. It may or may not have one or more auxiliary color buffers, a
155 depth buffer, a stencil buffer, or an accumulation buffer.
156
158 XVisualInfo is defined in Xutil.h. It is a structure that includes
159 visual, visualID, screen, and depth elements.
160 glXChooseVisual is implemented as a client-side utility using only
162 XGetVisualInfo and glXGetConfig. Calls to these two routines can be
163 used to implement selection algorithms other than the generic one
164 implemented by glXChooseVisual.
165 GLX implementers are strongly discouraged, but not proscribed, from
167 changing the selection algorithm used by glXChooseVisual. Therefore,
168 selections may change from release to release of the client-side
169 library.
170 There is no direct filter for picking only visuals that support GLX‐
172 Pixmaps. GLXPixmaps are supported for visuals whose GLX_BUFFER_SIZE is
173 one of the pixmap depths supported by the X server.
174
176 NULL is returned if an undefined GLX attribute is encountered in attri‐
177 bList.
178
180 glXCreateContext, glXGetConfig
181 GLXCHOOSEVISUAL()