| <refentry xmlns="http://docbook.org/ns/docbook" version="5.0" xml:base="" xml:id="eglGetProcAddress"> |
| <info> |
| <copyright> |
| <year>2003-2018</year> |
| <holder>The Khronos Group Inc.</holder> |
| </copyright> |
| </info> |
| <refmeta> |
| <refentrytitle>eglGetProcAddress</refentrytitle> |
| <manvolnum>3G</manvolnum> |
| </refmeta> |
| <refnamediv> |
| <refname>eglGetProcAddress</refname> |
| <refpurpose> |
| return a <acronym>GL</acronym> or an <acronym>EGL</acronym> |
| extension function |
| </refpurpose> |
| </refnamediv> |
| <refsynopsisdiv> |
| <title>C Specification</title> |
| <funcsynopsis> |
| <funcprototype> |
| <funcdef>void (* <function>eglGetProcAddress</function>)()</funcdef> |
| <paramdef>char const * <parameter>procname</parameter></paramdef> |
| </funcprototype> |
| </funcsynopsis> |
| </refsynopsisdiv> |
| <refsect1 xml:id="parameters"><title>Parameters</title> |
| <variablelist> |
| <varlistentry> |
| <term><parameter>procname</parameter></term> |
| <listitem> |
| <para> |
| Specifies the name of the function to return. |
| </para> |
| </listitem> |
| </varlistentry> |
| </variablelist> |
| </refsect1> |
| <refsect1 xml:id="description"><title>Description</title> |
| <para> |
| <function>eglGetProcAddress</function> returns the address of |
| the client API or EGL function named by |
| <parameter>procname</parameter>. <parameter>procname</parameter> |
| must be a null-terminated string. The pointer returned should be |
| cast to a function pointer matching the function's definition in |
| the corresponding API or extension specification. A return value |
| of <constant>NULL</constant> indicates that the specific |
| function does not exist for the implementation. |
| </para> |
| <para> |
| A non-<constant>NULL</constant> return value does not guarantee |
| that an extension function is actually supported at runtime. The |
| client must also make a corresponding query, such as |
| <function>glGetString</function>(<constant>GL_EXTENSIONS</constant>) |
| for OpenGL and OpenGL ES extensions; |
| <function>vgGetString</function>(<constant>VG_EXTENSIONS</constant>) |
| for OpenVG extensions; |
| <function>eglQueryString</function>(<parameter>display</parameter>, |
| <constant>EGL_EXTENSIONS</constant>); or query the EGL or client |
| API version for non-extension functions, to determine if a |
| function is supported by EGL or a specific client API context. |
| </para> |
| <para> |
| Client API function pointers returned by |
| <function>eglGetProcAddress</function> are independent of the |
| display and the currently bound client API context, and may be |
| used by any client API context which supports the function. |
| </para> |
| <para> |
| <function>eglGetProcAddress</function> may be queried for all |
| EGL and client API functions supported by the implementation |
| (whether those functions are extensions or not, and whether they |
| are supported by the current client API context or not). |
| </para> |
| <para> |
| For functions that are queryable with |
| <function>eglGetProcAddress</function>, implementations may |
| choose to also export those functions statically from the object |
| libraries implementing those functions. However, portable |
| clients cannot rely on this behavior. |
| </para> |
| </refsect1> |
| <refsect1 xml:id="notes"><title>Notes</title> |
| <para> |
| If the EGL version is not 1.5 or greater, only queries of EGL |
| and client API <emphasis>extension</emphasis> functions will |
| succeed. |
| </para> |
| </refsect1> |
| <refsect1 xml:id="seealso"><title>See Also</title> |
| <para> |
| <function>glGetString</function> |
| <citerefentry><refentrytitle>eglQueryString</refentrytitle></citerefentry> </para> |
| <function>vgGetString</function> |
| </refsect1> |
| <xi:include xmlns:xi="http://www.w3.org/2001/XInclude" href="copyright.xml"/> |
| </refentry> |