Adds "webgl" driver

This adds a COGL_DRIVER_WEBGL enum and a new driver description for
webgl in cogl-renderer.c. This also adds a COGL_DRIVER_FLAG_OPENGL_WEB
driver flag and a HAVE_COGL_WEBGL define which we can start to use to
handle special cases where webgl differs from gles2.

Reviewed-by: Neil Roberts <neil@linux.intel.com>

cogl/cogl-private.h

@@ -68,7 +68,8 @@ typedef enum
   COGL_PRIVATE_FEATURE_ANY_GL = 1L<<26,
   COGL_PRIVATE_FEATURE_GL_FIXED = 1L<<27,
   COGL_PRIVATE_FEATURE_GL_PROGRAMMABLE = 1L<<28,
-  COGL_PRIVATE_FEATURE_GL_EMBEDDED = 1L<<29
+  COGL_PRIVATE_FEATURE_GL_EMBEDDED = 1L<<29,
+  COGL_PRIVATE_FEATURE_GL_WEB = 1L<<30
 } CoglPrivateFeatureFlags;
 
 /* Sometimes when evaluating pipelines, either during comparisons or

cogl/cogl-renderer.c

@@ -155,6 +155,20 @@ static CoglDriverDescription _cogl_drivers[] =
     &_cogl_texture_driver_gles,
     COGL_GLES1_LIBNAME,
   },
+#endif
+#ifdef USING_EMSCRIPTEN
+  {
+    COGL_DRIVER_WEBGL,
+    "webgl",
+    0,
+    COGL_PRIVATE_FEATURE_ANY_GL |
+      COGL_PRIVATE_FEATURE_GL_EMBEDDED |
+      COGL_PRIVATE_FEATURE_GL_PROGRAMMABLE |
+      COGL_PRIVATE_FEATURE_GL_WEB,
+    &_cogl_driver_gles,
+    &_cogl_texture_driver_gles,
+    NULL,
+  },
 #endif
   {
     COGL_DRIVER_NOP,
@@ -421,6 +435,8 @@ driver_id_to_name (CoglDriver id)
         return "gles1";
       case COGL_DRIVER_GLES2:
         return "gles2";
+      case COGL_DRIVER_WEBGL:
+        return "webgl";
       case COGL_DRIVER_NOP:
         return "nop";
       case COGL_DRIVER_ANY:

cogl/cogl-renderer.h

@@ -332,6 +332,7 @@ cogl_renderer_remove_constraint (CoglRenderer *renderer,
  * @COGL_DRIVER_GL3: An OpenGL driver using the core GL 3.1 profile
  * @COGL_DRIVER_GLES1: An OpenGL ES 1.1 driver.
  * @COGL_DRIVER_GLES2: An OpenGL ES 2.0 driver.
+ * @COGL_DRIVER_WEBGL: A WebGL driver.
  *
  * Identifiers for underlying hardware drivers that may be used by
  * Cogl for rendering.
@@ -346,7 +347,8 @@ typedef enum
   COGL_DRIVER_GL,
   COGL_DRIVER_GL3,
   COGL_DRIVER_GLES1,
-  COGL_DRIVER_GLES2
+  COGL_DRIVER_GLES2,
+  COGL_DRIVER_WEBGL
 } CoglDriver;
 
 /**

configure.ac

@@ -708,6 +708,7 @@ AS_IF([test "x$enable_gles2" = "xyes"],
               [
                 GL_LIBRARY_DIRECTLY_LINKED=yes
                 COGL_GLES2_LIBNAME=""
+                AC_DEFINE([HAVE_COGL_WEBGL], 1, [Have WebGL for rendering])
               ],
 
               [