glXGetConfig(3g)

1GLXGETCONFIG(3G)                 OpenGL Manual                GLXGETCONFIG(3G)
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NAME

6       glXGetConfig - return information about GLX visuals
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C SPECIFICATION

9       int glXGetConfig(Display * dpy, XVisualInfo * vis, int attrib,
10                        int * value);
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PARAMETERS

13       dpy
14           Specifies the connection to the X server.
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16       vis
17           Specifies the visual to be queried. It is a pointer to an
18           XVisualInfo structure, not a visual ID or a pointer to a Visual.
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20       attrib
21           Specifies the visual attribute to be returned.
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23       value
24           Returns the requested value.
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DESCRIPTION

27       glXGetConfig sets value to the attrib value of windows or GLX pixmaps
28       created with respect to vis.  glXGetConfig returns an error code if it
29       fails for any reason. Otherwise, zero is returned.
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31       attrib is one of the following:
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33       GLX_USE_GL
34           True if OpenGL rendering is supported by this visual, False
35           otherwise.
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37       GLX_BUFFER_SIZE
38           Number of bits per color buffer. For RGBA visuals, GLX_BUFFER_SIZE
39           is the sum of GLX_RED_SIZE, GLX_GREEN_SIZE, GLX_BLUE_SIZE, and
40           GLX_ALPHA_SIZE. For color index visuals, GLX_BUFFER_SIZE is the
41           size of the color indexes.
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43       GLX_LEVEL
44           Frame buffer level of the visual. Level zero is the default frame
45           buffer. Positive levels correspond to frame buffers that overlay
46           the default buffer, and negative levels correspond to frame buffers
47           that underlay the default buffer.
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49       GLX_RGBA
50           True if color buffers store red, green, blue, and alpha values.
51           False if they store color indexes.
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53       GLX_DOUBLEBUFFER
54           True if color buffers exist in front/back pairs that can be
55           swapped, False otherwise.
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57       GLX_STEREO
58           True if color buffers exist in left/right pairs, False otherwise.
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60       GLX_AUX_BUFFERS
61           Number of auxiliary color buffers that are available. Zero
62           indicates that no auxiliary color buffers exist.
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64       GLX_RED_SIZE
65           Number of bits of red stored in each color buffer. Undefined if
66           GLX_RGBA is False.
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68       GLX_GREEN_SIZE
69           Number of bits of green stored in each color buffer. Undefined if
70           GLX_RGBA is False.
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72       GLX_BLUE_SIZE
73           Number of bits of blue stored in each color buffer. Undefined if
74           GLX_RGBA is False.
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76       GLX_ALPHA_SIZE
77           Number of bits of alpha stored in each color buffer. Undefined if
78           GLX_RGBA is False.
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80       GLX_DEPTH_SIZE
81           Number of bits in the depth buffer.
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83       GLX_STENCIL_SIZE
84           Number of bits in the stencil buffer.
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86       GLX_ACCUM_RED_SIZE
87           Number of bits of red stored in the accumulation buffer.
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89       GLX_ACCUM_GREEN_SIZE
90           Number of bits of green stored in the accumulation buffer.
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92       GLX_ACCUM_BLUE_SIZE
93           Number of bits of blue stored in the accumulation buffer.
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95       GLX_ACCUM_ALPHA_SIZE
96           Number of bits of alpha stored in the accumulation buffer.
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98       The X protocol allows a single visual ID to be instantiated with
99       different numbers of bits per pixel. Windows or GLX pixmaps that will
100       be rendered with OpenGL, however, must be instantiated with a color
101       buffer depth of GLX_BUFFER_SIZE.
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103       Although a GLX implementation can export many visuals that support GL
104       rendering, it must support at least one RGBA visual. This visual must
105       have at least one color buffer, a stencil buffer of at least 1 bit, a
106       depth buffer of at least 12 bits, and an accumulation buffer. Alpha
107       bitplanes are optional in this visual. However, its color buffer size
108       must be as great as that of the deepest TrueColor, DirectColor,
109       PseudoColor, or StaticColor visual supported on level zero, and it must
110       itself be made available on level zero.
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112       In addition, if the X server exports a PseudoColor or StaticColor
113       visual on framebuffer level 0, a color index visual is also required on
114       that level. It must have at least one color buffer, a stencil buffer of
115       at least 1 bit, and a depth buffer of at least 12 bits. This visual
116       must have as many color bitplanes as the deepest PseudoColor or
117       StaticColor visual supported on level 0.
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119       Applications are best written to select the visual that most closely
120       meets their requirements. Creating windows or GLX pixmaps with
121       unnecessary buffers can result in reduced rendering performance as well
122       as poor resource allocation.
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NOTES

125       XVisualInfo is defined in Xutil.h.  It is a structure that includes
126       visual, visualID, screen, and depth elements.
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ERRORS

129       GLX_NO_EXTENSION is returned if dpy does not support the GLX extension.
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131       GLX_BAD_SCREEN is returned if the screen of vis does not correspond to
132       a screen.
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134       GLX_BAD_ATTRIBUTE is returned if attrib is not a valid GLX attribute.
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136       GLX_BAD_VISUAL is returned if vis doesn't support GLX and an attribute
137       other than GLX_USE_GL is requested.
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COPYRIGHT

143       Copyright © 1991-2006 Silicon Graphics, Inc. This document is licensed
144       under the SGI Free Software B License. For details, see
145       http://oss.sgi.com/projects/FreeB/.
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AUTHORS

148       opengl.org
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152opengl.org                        07/13/2018                  GLXGETCONFIG(3G)