Name
eglGetProcAddress — return a GL or an EGL extension function
C Specification
void (* eglGetProcAddress(
|
char const * procname))(void); |
Parameters
-
procname -
Specifies the name of the function to return.
Description
eglGetProcAddress returns the address of
the client API or EGL function named by
procname. procname
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 NULL indicates that the specific
function does not exist for the implementation.
A non-NULL return value does not guarantee
that an extension function is actually supported at runtime. The
client must also make a corresponding query, such as
glGetString(GL_EXTENSIONS)
for OpenGL and OpenGL ES extensions;
vgGetString(VG_EXTENSIONS)
for OpenVG extensions;
eglQueryString(display,
EGL_EXTENSIONS); 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.
Client API function pointers returned by
eglGetProcAddress 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.
eglGetProcAddress 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).
For functions that are queryable with
eglGetProcAddress, implementations may
choose to also export those functions statically from the object
libraries implementing those functions. However, portable
clients cannot rely on this behavior.
Notes
If the EGL version is not 1.5 or greater, only queries of EGL and client API extension functions will succeed.
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