Index for Section 3

Alphabetical listing for G

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glXChooseVisual()
NAME
  glXChooseVisual - return a visual that matches specified attributes

SYNOPSIS
  XVisualInfo* glXChooseVisual(
	  Display *dpy,
	  int screen,
	  int *attribList );

PARAMETERS
  dpy Specifies the connection to the X server.

  screen
      Specifies the screen number.

  attribList
      Specifies a list of boolean attributes and integer attribute/value
      pairs. The last attribute must be None.

DESCRIPTION
  glXChooseVisual() returns a pointer to an XVisualInfo structure describing
  the visual that best meets a minimum specification. The boolean GLX
  attributes of the visual that is returned will match the specified values,
  and the integer GLX attributes will meet or exceed the specified minimum
  values. If all other attributes are equivalent, then TrueColor and
  PseudoColor visuals have priority over DirectColor and StaticColor visuals,
  respectively.	 If no conforming visual exists, NULL is returned. To free
  the data returned by this function, use XFree.

  All boolean GLX attributes default to False except GLX_USE_GL, which
  defaults to True. All integer GLX attributes default to zero. Default
  specifications are superseded by attributes included in attribList. Boolean
  attributes included in attribList are understood to be True. Integer
  attributes and enumerated type attributes are followed immediately by the
  corresponding desired or minimum value. The list must be terminated with
  None.

  The interpretations of the various GLX visual attributes are as follows:

  GLX_USE_GL
      Ignored. Only visuals that can be rendered with GLX are considered.

  GLX_BUFFER_SIZE
      Must be followed by a nonnegative integer that indicates the desired
      color index buffer size.	The smallest index buffer of at least the
      specified size is preferred. Ignored if GLX_RGBA is asserted.

  GLX_LEVEL
      Must be followed by an integer buffer-level specification. This
      specification is honored exactly.	 Buffer level zero corresponds to the
      main frame buffer of the display. Buffer level one is the first overlay
      frame buffer, level two the second overlay frame buffer, and so on.
      Negative buffer levels correspond to underlay frame buffers.

  GLX_RGBA
      If present, only TrueColor and DirectColor visuals are considered.
      Otherwise, only PseudoColor and StaticColor visuals are considered.

  GLX_DOUBLEBUFFER
      If present, only double-buffered visuals are considered.	Otherwise,
      only single-buffered visuals are considered.

  GLX_STEREO
      If present, only stereo visuals are considered. Otherwise, only
      monoscopic visuals are considered.

  GLX_AUX_BUFFERS
      Must be followed by a nonnegative integer that indicates the desired
      number of auxiliary buffers.  Visuals with the  smallest number of
      auxiliary buffers that meets or exceeds the specified number are
      preferred.

  GLX_RED_SIZE
      Must be followed by a nonnegative minimum size specification. If this
      value is zero, the smallest available red buffer is preferred.
      Otherwise, the largest available red buffer of at least the minimum
      size is preferred.

  GLX_GREEN_SIZE
      Must be followed by a nonnegative minimum size specification. If this
      value is zero, the smallest available green buffer is preferred.
      Otherwise, the largest available green buffer of at least the minimum
      size is preferred.

  GLX_BLUE_SIZE
      Must be followed by a nonnegative minimum size specification. If this
      value is zero, the smallest available blue buffer is preferred.
      Otherwise, the largest available blue buffer of at least the minimum
      size is preferred.

  GLX_ALPHA_SIZE
      Must be followed by a nonnegative minimum size specification. If this
      value is zero, the smallest available alpha buffer is preferred.
      Otherwise, the largest available alpha buffer of at least the minimum
      size is preferred.

  GLX_DEPTH_SIZE
      Must be followed by a nonnegative minimum size specification. If this
      value is zero, visuals with no depth buffer are preferred. Otherwise,
      the largest available depth buffer of at least the minimum size is
      preferred.

  GLX_STENCIL_SIZE
      Must be followed by a nonnegative integer that indicates the desired
      number of stencil bitplanes.  The smallest stencil buffer of at least
      the specified size is preferred. If the desired value is zero, visuals
      with no stencil buffer are preferred.

  GLX_ACCUM_RED_SIZE
      Must be followed by a nonnegative minimum size specification. If this
      value is zero, visuals with no red accumulation buffer are preferred.
      Otherwise, the largest possible red accumulation buffer of at least the
      minimum size is preferred.

  GLX_ACCUM_GREEN_SIZE
      Must be followed by a nonnegative minimum size specification. If this
      value is zero, visuals with no green accumulation buffer are preferred.
      Otherwise, the largest possible green accumulation buffer of at least
      the minimum size is preferred.

  GLX_ACCUM_BLUE_SIZE
      Must be followed by a nonnegative minimum size specification. If this
      value is zero, visuals with no blue accumulation buffer are preferred.
      Otherwise, the largest possible blue accumulation buffer of at least
      the minimum size is preferred.

  GLX_ACCUM_ALPHA_SIZE
      Must be followed by a nonnegative minimum size specification. If this
      value is zero, visuals with no alpha accumulation buffer are preferred.
      Otherwise, the largest possible alpha accumulation buffer of at least
      the minimum size is preferred.

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

  glXChooseVisual() is implemented as a client-side utility using only
  XGetVisualInfo and glXGetConfig(). Calls to these two routines can be used
  to implement selection algorithms other than the generic one implemented by
  glXChooseVisual().

  GLX implementers are strongly discouraged, but not proscribed, from
  changing the selection algorithm used by glXChooseVisual().  Therefore,
  selections may change from release to release of the client-side library.

  There is no direct filter for picking only visuals that support GLXPixmaps.
  GLXPixmaps are supported for visuals whose GLX_BUFFER_SIZE is one of the
  pixmap depths supported by the X server.

ERRORS
  NULL is returned if an undefined GLX attribute is encountered in
  attribList.

EXAMPLES
None};
  attribList = {GLX_RGBA, GLX_RED_SIZE, 4, GLX_GREEN_SIZE, 4, GLX_BLUE_SIZE, 4,
      Specifies a single-buffered RGB visual in the normal frame buffer, not
      an overlay or underlay buffer. The returned visual supports at least
      four bits each of red, green, and blue, and possibly no bits of alpha.
      It does not support color index mode, double-buffering, or stereo
      display. It may or may not have one or more auxiliary color buffers, a
      depth buffer, a stencil buffer, or an accumulation buffer.

SEE ALSO
  glXCreateContext(3), glXGetConfig(3)

Index for Section 3

Alphabetical listing for G

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