vo_opengl: add a generic EGL function loader function

This is pretty trivial, but also quite annoying due to details like
mismatching eglGetProcAddress() function signature (most callers just
cast the function pointer), and ARM/Linux hacks. So move them all to one
place.

video/out/opengl/context_angle.c

@@ -623,11 +623,6 @@ static int GLAPIENTRY angle_swap_interval(int interval)
     }
 }
 
-static void *get_proc_address(const GLubyte *proc_name)
-{
-    return eglGetProcAddress(proc_name);
-}
-
 static int angle_init(struct MPGLContext *ctx, int flags)
 {
     struct priv *p = ctx->priv;
@@ -709,7 +704,7 @@ static int angle_init(struct MPGLContext *ctx, int flags)
     if (!surface_ok)
         goto fail;
 
-    mpgl_load_functions(ctx->gl, get_proc_address, NULL, vo->log);
+    mpegl_load_functions(ctx->gl, vo->log);
 
     current_ctx = ctx;
     ctx->gl->SwapInterval = angle_swap_interval;

video/out/opengl/context_drm_egl.c

@@ -307,9 +307,7 @@ static int drm_egl_init(struct MPGLContext *ctx, int flags)
         return -1;
     }
 
-    const char *egl_exts = eglQueryString(p->egl.display, EGL_EXTENSIONS);
-    void *(*gpa)(const GLubyte*) = (void *(*)(const GLubyte*))eglGetProcAddress;
-    mpgl_load_functions(ctx->gl, gpa, egl_exts, ctx->vo->log);
+    mpegl_load_functions(ctx->gl, ctx->vo->log);
 
     ctx->native_display_type = "drm";
     ctx->native_display = (void *)(intptr_t)p->kms->fd;

video/out/opengl/context_mali_fbdev.c

@@ -49,16 +49,6 @@ static bool get_fbdev_size(int *w, int *h)
     return ok;
 }
 
-static void *get_proc_address(const GLubyte *name)
-{
-    void *p = eglGetProcAddress(name);
-    // EGL 1.4 (supported by the MALI drivers) does not necessarily return
-    // function pointers for core functions.
-    if (!p)
-        p = dlsym(RTLD_DEFAULT, name);
-    return p;
-}
-
 struct priv {
     struct mp_log *log;
     struct GL *gl;
@@ -127,8 +117,7 @@ static int mali_init(struct MPGLContext *ctx, int flags)
 
     ctx->gl = talloc_zero(ctx, GL);
 
-    const char *exts = eglQueryString(p->egl_display, EGL_EXTENSIONS);
-    mpgl_load_functions(ctx->gl, get_proc_address, exts, p->log);
+    mpegl_load_functions(ctx->gl, p->log);
 
     return 0;
 

video/out/opengl/context_rpi.c

@@ -208,16 +208,6 @@ fail:
     return -1;
 }
 
-static void *get_proc_address(const GLubyte *name)
-{
-    void *p = eglGetProcAddress(name);
-    // EGL 1.4 (supported by the RPI firmware) does not necessarily return
-    // function pointers for core functions.
-    if (!p)
-        p = dlsym(RTLD_DEFAULT, name);
-    return p;
-}
-
 static int rpi_init(struct MPGLContext *ctx, int flags)
 {
     struct priv *p = ctx->priv;
@@ -242,8 +232,7 @@ static int rpi_init(struct MPGLContext *ctx, int flags)
 
     ctx->gl = talloc_zero(ctx, GL);
 
-    const char *exts = eglQueryString(p->egl_display, EGL_EXTENSIONS);
-    mpgl_load_functions(ctx->gl, get_proc_address, exts, p->log);
+    mpegl_load_functions(ctx->gl, p->log);
 
     ctx->native_display_type = "MPV_RPI_WINDOW";
     ctx->native_display = p->win_params;

video/out/opengl/context_wayland.c

@@ -67,7 +67,6 @@ static int egl_create_context(struct vo_wayland_state *wl, MPGLContext *ctx,
                               int flags)
 {
     GL *gl = ctx->gl;
-    const char *eglstr = "";
 
     if (!(wl->egl_context.egl.dpy = eglGetDisplay(wl->display.display)))
         return -1;
@@ -82,10 +81,7 @@ static int egl_create_context(struct vo_wayland_state *wl, MPGLContext *ctx,
 
     eglMakeCurrent(wl->egl_context.egl.dpy, NULL, NULL, wl->egl_context.egl.ctx);
 
-    eglstr = eglQueryString(wl->egl_context.egl.dpy, EGL_EXTENSIONS);
-
-    mpgl_load_functions(gl, (void*(*)(const GLubyte*))eglGetProcAddress, eglstr,
-                        wl->log);
+    mpegl_load_functions(gl, wl->log);
 
     ctx->native_display_type = "wl";
     ctx->native_display = wl->display.display;

video/out/opengl/context_x11egl.c

@@ -131,10 +131,7 @@ static int mpegl_init(struct MPGLContext *ctx, int flags)
         goto uninit;
     }
 
-    const char *egl_exts = eglQueryString(p->egl_display, EGL_EXTENSIONS);
-
-    void *(*gpa)(const GLubyte*) = (void *(*)(const GLubyte*))eglGetProcAddress;
-    mpgl_load_functions(ctx->gl, gpa, egl_exts, vo->log);
+    mpegl_load_functions(ctx->gl, vo->log);
 
     ctx->native_display_type = "x11";
     ctx->native_display = vo->x11->display;

video/out/opengl/egl_helpers.c

@@ -15,6 +15,12 @@
  * License along with mpv.  If not, see <http://www.gnu.org/licenses/>.
  */
 
+#include "config.h"
+
+#if HAVE_LIBDL
+#include <dlfcn.h>
+#endif
+
 #include "common/common.h"
 
 #include "egl_helpers.h"
@@ -199,3 +205,28 @@ bool mpegl_create_context_opts(EGLDisplay display, struct mp_log *log,
     return false;
 }
 
+static void *mpegl_get_proc_address(void *ctx, const char *name)
+{
+    void *p = eglGetProcAddress(name);
+#if defined(__GLIBC__) && HAVE_LIBDL
+    // Some crappy ARM/Linux things do not provide EGL 1.5, so above call does
+    // not necessarily return function pointers for core functions. Try to get
+    // them from a loaded GLES lib. As POSIX leaves RTLD_DEFAULT "reserved",
+    // use it only with glibc.
+    if (!p)
+        p = dlsym(RTLD_DEFAULT, name);
+#endif
+    return p;
+}
+
+// Load gl version and function pointers into *gl.
+// Expects a current EGL context set.
+void mpegl_load_functions(struct GL *gl, struct mp_log *log)
+{
+    const char *egl_exts = "";
+    EGLDisplay display = eglGetCurrentDisplay();
+    if (display != EGL_NO_DISPLAY)
+        egl_exts = eglQueryString(display, EGL_EXTENSIONS);
+
+    mpgl_load_functions2(gl, mpegl_get_proc_address, NULL, egl_exts, log);
+}

video/out/opengl/egl_helpers.h

@@ -27,4 +27,7 @@ bool mpegl_create_context_opts(EGLDisplay display, struct mp_log *log,
                                struct mpegl_opts *opts,
                                EGLContext *out_context, EGLConfig *out_config);
 
+struct GL;
+void mpegl_load_functions(struct GL *gl, struct mp_log *log);
+
 #endif