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glXIntro

Chapter 9

240

/* wait a while */

sleep(10);

}

Notes

A color map must be created and passed to XCreateWindow. See the preceding example

code.

A GLX context must be created and attached to an X drawable before OpenGL

commands can be executed.

OpenGL commands issued while no context/drawable pair is current result in undeﬁned

behavior.

Exposure events indicate that all buffers associated with the speciﬁed window may be

damaged and should be repainted. Although certain buffers of some visuals on some

systems may never require repainting (the depth buffer, for example), it is incorrect to

write a program assuming that these buffers will not be damaged.

GLX commands manipulate XVisualInfo structures rather than pointers to visuals or

visual IDs. XVisualInfo structures contain visual, visualID, screen, and depth elements,

as well as other X-speciﬁc information.

Using GLX Extensions

All supported GLX extensions will have a corresponding deﬁnition in glx.h and a token

in the extension string returned by glXQueryExtensionsString. For example, if the

EXT_visual_info extension is supported, then this token will be deﬁned in glx.h and

EXT_visual_info will appear in the extension string returned by

glXQueryExtensionsString. The deﬁnitions in glx.h can be used at compile time to

determine if procedure calls corresponding to an extension exist in the library.

GLX 1.1 and GLX 1.2

GLX 1.2 is now supported. It is backward compatible with GLX 1.1 and GLX 1.0.

GLX 1.2 corresponds to OpenGL version 1.1 and introduces the following new call:

glXGetCurrentDisplay.

GLX 1.1 corresponds to OpenGL version 1.0 and introduces the following new calls:

glXQueryExtensionsString, glXQueryServerString, and glXGetClientString.

Call glXQueryVersion to determine at runtime what version of GLX is available.

glXQueryVersion returns the version that is supported on the connection. Thus if 1.2 is

returned, both the client and server support GLX 1.2. You can also check the GLX

version at compile time: GLX_VERSION_1_1 will be deﬁned in glx.h if GLX 1.1 calls are

supported and GLX_VERSION_1_2 will be deﬁned if GLX 1.2 calls are supported.

HP b2600 Reference Guide

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