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diff --git a/auto/doc/basic.html b/auto/doc/basic.html new file mode 100644 index 0000000..693575b --- /dev/null +++ b/auto/doc/basic.html @@ -0,0 +1,180 @@ +<h2>Initializing GLEW</h2> +<p> +First you need to create a valid OpenGL rendering context and call +<tt>glewInit()</tt> to initialize the extension entry points. If +<tt>glewInit()</tt> returns <tt>GLEW_OK</tt>, the initialization +succeeded and you can use the available extensions as well as core +OpenGL functionality. For example: +</p> + +<p class="pre"> +#include <GL/glew.h><br> +#include <GL/glut.h><br> +...<br> +glutInit(&argc, argv);<br> +glutCreateWindow("GLEW Test");<br> +GLenum err = glewInit();<br> +if (GLEW_OK != err)<br> +{<br> + /* Problem: glewInit failed, something is seriously wrong. */<br> + fprintf(stderr, "Error: %s\n", glewGetErrorString(err));<br> + ...<br> +}<br> +fprintf(stdout, "Status: Using GLEW %s\n", glewGetString(GLEW_VERSION));<br> +</p> + +<h2>Checking for Extensions</h2> + +<p> +Starting from GLEW 1.1.0, you can find out if a particular extension +is available on your platform by querying globally defined variables +of the form <tt>GLEW_{extension_name}</tt>: +</p> + +<p class="pre"> +if (GLEW_ARB_vertex_program)<br> +{<br> + /* It is safe to use the ARB_vertex_program extension here. */<br> + glGenProgramsARB(...);<br> +}<br> +</p> + +<p> +<b>In GLEW 1.0.x, a global structure was used for this task. To ensure +binary compatibility between releases, the struct was replaced with a +set of variables.</b> +</p> + +<p> +You can also check for core OpenGL functionality. For example, to +see if OpenGL 1.3 is supported, do the following: +</p> + +<p class="pre"> +if (GLEW_VERSION_1_3)<br> +{<br> + /* Yay! OpenGL 1.3 is supported! */<br> +}<br> +</p> + +<p> +In general, you can check if <tt>GLEW_{extension_name}</tt> or +<tt>GLEW_VERSION_{version}</tt> is true or false. +</p> + +<p> +It is also possible to perform extension checks from string +input. Starting from the 1.3.0 release, use <tt>glewIsSupported</tt> +to check if the required core or extension functionality is +available: +</p> + +<p class="pre"> +if (glewIsSupported("GL_VERSION_1_4 GL_ARB_point_sprite"))<br> +{<br> + /* Great, we have OpenGL 1.4 + point sprites. */<br> +}<br> +</p> + +<p> +For extensions only, <tt>glewGetExtension</tt> provides a slower alternative +(GLEW 1.0.x-1.2.x). <b>Note that in the 1.3.0 release </b> +<tt>glewGetExtension</tt> <b>was replaced with </b> +<tt>glewIsSupported</tt>. +</p> + +<p class="pre"> +if (glewGetExtension("GL_ARB_fragment_program"))<br> +{<br> + /* Looks like ARB_fragment_program is supported. */<br> +}<br> +</p> + +<h2>Experimental Drivers</h2> + +<p> +GLEW obtains information on the supported extensions from the graphics +driver. Experimental or pre-release drivers, however, might not +report every available extension through the standard mechanism, in +which case GLEW will report it unsupported. To circumvent this +situation, the <tt>glewExperimental</tt> global switch can be turned +on by setting it to <tt>GL_TRUE</tt> before calling +<tt>glewInit()</tt>, which ensures that all extensions with valid +entry points will be exposed. +</p> + +<h2>Platform Specific Extensions</h2> + +<p> +Platform specific extensions are separated into two header files: +<tt>wglew.h</tt> and <tt>glxew.h</tt>, which define the available +<tt>WGL</tt> and <tt>GLX</tt> extensions. To determine if a certain +extension is supported, query <tt>WGLEW_{extension name}</tt> or +<tt>GLXEW_{extension_name}</tt>. For example: +</p> + +<p class="pre"> +#include <GL/wglew.h><br> +<br> +if (WGLEW_ARB_pbuffer)<br> +{<br> + /* OK, we can use pbuffers. */<br> +}<br> +else<br> +{<br> + /* Sorry, pbuffers will not work on this platform. */<br> +}<br> +</p> + +<p> +Alternatively, use <tt>wglewIsSupported</tt> or +<tt>glxewIsSupported</tt> to check for extensions from a string: +</p> + +<p class="pre"> +if (wglewIsSupported("WGL_ARB_pbuffer"))<br> +{<br> + /* OK, we can use pbuffers. */<br> +}<br> +</p> + +<h2>Utilities</h2> + +<p> +GLEW provides two command-line utilities: one for creating a list of +available extensions and visuals; and another for verifying extension +entry points. +</p> + +<h3>visualinfo: extensions and visuals</h3> + +<p> +<tt>visualinfo</tt> is an extended version of <tt>glxinfo</tt>. The +Windows version creates a file called <tt>visualinfo.txt</tt>, which +contains a list of available OpenGL, WGL, and GLU extensions as well +as a table of visuals aka. pixel formats. Pbuffer and MRT capable +visuals are also included. For additional usage information, type +<tt>visualinfo -h</tt>. +</p> + +<h3>glewinfo: extension verification utility</h3> + +<p> +<tt>glewinfo</tt> allows you to verify the entry points for the +extensions supported on your platform. The Windows version +reports the results to a text file called <tt>glewinfo.txt</tt>. The +Unix version prints the results to <tt>stdout</tt>. +</p> + +<p>Windows usage:</p> + <blockquote><pre>glewinfo [-pf <id>]</pre></blockquote> + +<p>where <tt><id></tt> is the pixel format id for which the +capabilities are displayed.</p> + +<p>Unix usage:</p> +<blockquote><pre>glewinfo [-display <dpy>] [-visual <id>]</pre></blockquote> + +<p>where <tt><dpy></tt> is the X11 display and <tt><id></tt> is +the visual id for which the capabilities are displayed.</p> + |