gdkglcontext.c: Re-create an OpenGL/ES 3.0 context if needed

Currently, we create an OpenGL/ES 2.0 context if GLES is requested or required,
but it may not support the needed extensions for it to work, such as
OES_vertex_half_float.  So, if that is the case, create an OpenGL/ES 3.0
context to replace the OpenGL/ES 2.0 context that we have created, so that we
have the needed OpenGL/ES features, in which the OpenGL/ES 2.0 context will
then be dropped.

gdk/gdkglcontext.c

@@ -121,6 +121,7 @@ typedef struct {
 #ifdef HAVE_EGL
   EGLContext egl_context;
   EGLBoolean (*eglSwapBuffersWithDamage) (EGLDisplay, EGLSurface, const EGLint *, EGLint);
+  guint use_es3 : 1;
 #endif
 } GdkGLContextPrivate;
 
@@ -274,12 +275,12 @@ gdk_api_to_egl_api (GdkGLAPI api)
     }
 }
 
-static GdkGLAPI
-gdk_gl_context_create_egl_context (GdkGLContext *context,
-                                   GdkGLAPI      api,
-                                   gboolean      legacy)
+static EGLContext
+gdk_gl_context_create_actual_egl_context (GdkGLContext *context,
+                                          GdkGLAPI      api,
+                                          gboolean      legacy,
+                                          gboolean      use_es3)
 {
-  GdkGLContextPrivate *priv = gdk_gl_context_get_instance_private (context);
   GdkDisplay *display = gdk_gl_context_get_display (context);
   EGLDisplay egl_display = gdk_display_get_egl_display (display);
   GdkGLContext *share = gdk_display_get_gl_context (display);
@@ -289,21 +290,18 @@ gdk_gl_context_create_egl_context (GdkGLContext *context,
   EGLint context_attribs[N_EGL_ATTRS], i = 0, flags = 0;
   gboolean debug_bit, forward_bit;
   int min_major, min_minor, major = 0, minor = 0;
-  G_GNUC_UNUSED gint64 start_time = GDK_PROFILER_CURRENT_TIME;
-
-  if (!gdk_gl_context_is_api_allowed (context, api, NULL))
-    return 0;
 
   /* We will use the default version matching the context status
    * unless the user requested a version which makes sense */
   gdk_gl_context_get_matching_version (api, legacy,
-                                       &min_major, &min_minor);
+                                       &min_major, &min_minor,
+                                       use_es3);
   gdk_gl_context_get_clipped_version (context,
                                       min_major, min_minor,
                                       &major, &minor);
 
   if (!eglBindAPI (gdk_api_to_egl_api (api)))
-    return 0;
+    return NULL;
 
   debug_bit = gdk_gl_context_get_debug_enabled (context);
   forward_bit = gdk_gl_context_get_forward_compatible (context);
@@ -353,12 +351,113 @@ gdk_gl_context_create_egl_context (GdkGLContext *context,
                           share ? share_priv->egl_context : EGL_NO_CONTEXT,
                           context_attribs);
 
+  return ctx;
+}
+
+static GdkGLAPI
+gdk_gl_context_create_egl_context (GdkGLContext *context,
+                                   GdkGLAPI      api,
+                                   gboolean      legacy)
+{
+  GdkGLContextPrivate *priv = gdk_gl_context_get_instance_private (context);
+  GdkDisplay *display = gdk_gl_context_get_display (context);
+  EGLDisplay egl_display = gdk_display_get_egl_display (display);
+  GdkGLContext *share = gdk_display_get_gl_context (display);
+  GdkGLContextPrivate *share_priv = gdk_gl_context_get_instance_private (share);
+  EGLContext ctx;
+  gboolean use_es3 = FALSE;
+  gboolean share_has_half_float = FALSE;
+  G_GNUC_UNUSED gint64 start_time = GDK_PROFILER_CURRENT_TIME;
+
+  if (!gdk_gl_context_is_api_allowed (context, api, NULL))
+    return 0;
+
+  /*
+   * The new context must use an OpenGL/ES 3.0 context if the
+   * shared context is an OpenGL/ES 3.0 context
+   */
+  use_es3 = share != NULL ? share_priv->use_es3 : FALSE;
+  share_has_half_float = share != NULL ? share_priv->has_half_float : FALSE;
+
+  ctx = gdk_gl_context_create_actual_egl_context (context,
+                                                  api,
+                                                  legacy,
+                                                  use_es3);
+
+  /*
+   * If we are using an OpenGL/ES 2.0 context, check whether
+   * it supports the needed extension(s) if not already done so
+   */
+  if (api == GDK_GL_API_GLES &&
+      !share_has_half_float &&
+      !use_es3 &&
+      ctx != NULL)
+    {
+      gboolean surfaceless = !gdk_draw_context_is_in_frame (GDK_DRAW_CONTEXT (context));
+      EGLContext ctx_es3 = NULL;
+      gboolean destroy_es2_ctx = FALSE;
+      EGLSurface egl_surface;
+
+      if (!surfaceless)
+        egl_surface = gdk_surface_get_egl_surface (gdk_gl_context_get_surface (context));
+      else
+        egl_surface = EGL_NO_SURFACE;
+
+      if (eglMakeCurrent (egl_display,
+                          egl_surface,
+                          egl_surface,
+                          ctx))
+        {
+          /*
+           * If we don't support the needed extension(s) in the OpenGL/ES 2.0 context,
+           * destroy the context and re-create an OpenGL/ES 3.0 context, and use it
+           * if it is successfully created.
+           */
+          if (epoxy_gl_version () < 30 &&
+              !epoxy_has_gl_extension ("OES_vertex_half_float"))
+            {
+              GDK_DISPLAY_DEBUG (display, OPENGL,
+                                 "No OES_vertex_half_float extension found.\n"
+                                 "Creating new OpenGL/ES 3.0 context to replace OpenGL/ES 2.0 context...");
+              ctx_es3 = gdk_gl_context_create_actual_egl_context (context,
+                                                                  api,
+                                                                  legacy,
+                                                                  TRUE);
+
+              if (ctx_es3 != NULL)
+                use_es3 = TRUE;
+
+              destroy_es2_ctx = TRUE;
+            }
+          else
+            priv->has_half_float = TRUE;
+
+          eglMakeCurrent (egl_display,
+                          EGL_NO_SURFACE,
+                          EGL_NO_SURFACE,
+                          EGL_NO_CONTEXT);
+        }
+      else
+        /* no point going on if the EGLContext isn't working */
+        destroy_es2_ctx = TRUE;
+
+      if (destroy_es2_ctx)
+        {
+          eglDestroyContext (egl_display, ctx);
+          ctx = NULL;
+        }
+
+      if (use_es3)
+        ctx = ctx_es3;
+    }
+
   if (ctx == NULL)
-      return 0;
+    return 0;
 
   GDK_DISPLAY_DEBUG (display, OPENGL, "Created EGL context[%p]", ctx);
 
   priv->egl_context = ctx;
+  priv->use_es3 = use_es3;
   gdk_gl_context_set_is_legacy (context, legacy);
 
   if (epoxy_has_egl_extension (egl_display, "EGL_KHR_swap_buffers_with_damage"))
@@ -989,7 +1088,8 @@ void
 gdk_gl_context_get_matching_version (GdkGLAPI  api,
                                      gboolean  legacy,
                                      int      *major,
-                                     int      *minor)
+                                     int      *minor,
+                                     gboolean  use_es3)
 {
   int maj, min;
 
@@ -1008,8 +1108,16 @@ gdk_gl_context_get_matching_version (GdkGLAPI  api,
     }
   else
     {
-      maj = GDK_GL_MIN_GLES_VERSION_MAJOR;
-      min = GDK_GL_MIN_GLES_VERSION_MINOR;
+      if (use_es3)
+        {
+          maj = GDK_GL_MIN_GLES3_VERSION_MAJOR;
+          min = GDK_GL_MIN_GLES3_VERSION_MINOR;
+        }
+      else
+        {
+          maj = GDK_GL_MIN_GLES_VERSION_MAJOR;
+          min = GDK_GL_MIN_GLES_VERSION_MINOR;
+        }
     }
 
   if (major != NULL)
@@ -1554,8 +1662,11 @@ gdk_gl_context_check_extensions (GdkGLContext *context)
       glGetIntegerv (GL_MAX_LABEL_LENGTH, &priv->max_debug_label_length);
     }
 
-  priv->has_half_float = gdk_gl_context_check_version (context, 3, 0, 3, 0) ||
-                         epoxy_has_gl_extension ("OES_vertex_half_float");
+  if (!priv->has_half_float)
+    {
+      priv->has_half_float = gdk_gl_context_check_version (context, 3, 0, 3, 0) ||
+                             epoxy_has_gl_extension ("OES_vertex_half_float");
+    }
 
 #ifdef G_ENABLE_DEBUG
   {

gdk/gdkglcontextprivate.h

@@ -44,6 +44,8 @@ G_BEGIN_DECLS
 #define GDK_GL_MIN_GL_LEGACY_VERSION_MINOR (0)
 #define GDK_GL_MIN_GLES_VERSION_MAJOR (2)
 #define GDK_GL_MIN_GLES_VERSION_MINOR (0)
+#define GDK_GL_MIN_GLES3_VERSION_MAJOR (3)
+#define GDK_GL_MIN_GLES3_VERSION_MINOR (0)
 
 typedef enum {
   GDK_GL_NONE = 0,
@@ -137,7 +139,8 @@ void                    gdk_gl_context_get_clipped_version      (GdkGLContext
 void                    gdk_gl_context_get_matching_version     (GdkGLAPI         api,
                                                                  gboolean         legacy,
                                                                  int             *major,
-                                                                 int             *minor);
+                                                                 int             *minor,
+                                                                 gboolean         use_es3);
 
 gboolean                gdk_gl_context_has_unpack_subimage      (GdkGLContext    *context);
 void                    gdk_gl_context_push_debug_group         (GdkGLContext    *context,

gdk/x11/gdkglcontext-glx.c

@@ -489,7 +489,8 @@ gdk_x11_context_create_glx_context (GdkGLContext *context,
   /* We will use the default version matching the context status
    * unless the user requested a version which makes sense */
   gdk_gl_context_get_matching_version (api, legacy,
-                                       &min_major, &min_minor);
+                                       &min_major, &min_minor,
+                                       FALSE);
   gdk_gl_context_get_clipped_version (context, min_major, min_minor,
                                       &major, &minor);