glXGetConfig

Return information about GLX visuals.

C Specification

   int glXGetConfig(Display     *dpy,

                    XVisualInfo *vis,

                    int          attrib,

                    int         *value)

Parameters

dpy: Specifies the connection to the X server.
vis: Specifies the visual to be queried. It is a pointer to an XVisualInfo structure, not a visual ID or a pointer to a Visual.
attrib: Specifies the visual attribute to be returned.
value: Returns the requested value.

Description

glXGetConfig sets value to the attrib value of windows or GLX pixmaps created with respect to vis. glXGetConfig returns an error code if it fails for any reason. Otherwise, zero is returned.

attrib is one of the following:

GLX_USE_GL True if IVL rendering is supported by this visual, False otherwise.
GLX_BUFFER_SIZE Number of bits per color buffer. For visuals that support RGBA rendering, GLX_BUFFER_SIZE is the sum of GLX_RED_SIZE, GLX_GREEN_SIZE, GLX_BLUE_SIZE, and GLX_ALPHA_SIZE.
GLX_LEVEL Frame buffer level of the visual. Level zero is the default frame buffer. Positive levels correspond to frame buffers that overlay the default buffer, and negative levels correspond to frame buffers that underlay the default buffer.
GLX_RGBA True if the visual supports RGBA rendering, False otherwise.
GLX_DOUBLEBUFFER True if color buffers exist in front/back pairs that can be swapped, False otherwise.
GLX_RED_SIZE Number of bits of red stored in each color buffer. Undefined if GLX_RGBA is False.
GLX_GREEN_SIZE Number of bits of green stored in each color buffer. Undefined if GLX_RGBA is False.
GLX_BLUE_SIZE Number of bits of blue stored in each color buffer. Undefined if GLX_RGBA is False.
GLX_ALPHA_SIZE Number of bits of alpha stored in each color buffer. Undefined if GLX_RGBA is False.
GLX_X_VISUAL_TYPE_EXT The name of the X visual type for this visual.

The X protocol allows a single visual ID to be instantiated with different numbers of bits per pixel. Windows or GLX pixmaps that will be rendered with IVL, however, must be instantiated with a color buffer depth of GLX_BUFFER_SIZE.

Applications are best written to select the visual that most closely meets their requirements. Creating windows or GLX pixmaps with unnecessary buffers can result in reduced rendering performance as well as poor resource allocation.

Notes

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

Errors

GLX_NO_EXTENSION is returned if dpy does not support the GLX extension.

GLX_BAD_SCREEN is returned if the screen of vis does not correspond to a screen.

GLX_BAD_ATTRIB is returned if attrib is not a valid GLX attribute.

GLX_BAD_VISUAL is returned if vis doesn't support GLX and an attribute other than GLX_USE_GL is requested.

glXGetConfig

Technical documentation

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C Specification

Parameters

Description

Notes

Errors

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