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glXChooseVisual

Chapter 3

glXChooseVisual

glXChooseVisual: return a visual that matches speciﬁed attributes.

C Speciﬁcation

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 Default speciﬁcations are superseded by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 non-negative 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.

HP b2600 Reference Guide

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