WinRT: added experimental OpenGL ES 2.0 support

A port of the ANGLE library (OpenGL ES 2.0 for Direct3D) to WinRT, via https://github.com/stammen/angleproject, is used as a base.

To enable, clone 'angleproject' into the directory one above where SDL/WinRT is, open the file SDL/include/SDL_config_winrt.h, and uncomment the #defines that begin with 'SDL_VIDEO_OPENGL'.  From there, apps can create an OpenGL capable SDL_Window via the flag, SDL_WINDOW_OPENGL, and an OpenGL ES 2 context via SDL_GL_CreateContext.  The Direct3D 11.1 renderer cannot be used alongside SDL_WINDOW_OPENGL.  Only Windows 8/8.1 is supported for now.  Shaders may need to be precompiled, in some (all?) cases.

VisualC-WinRT/SDL/SDL-WinRT_VS2012.vcxproj

@@ -145,6 +145,7 @@
     <ClCompile Include="..\..\src\video\SDL_blit_slow.c" />
     <ClCompile Include="..\..\src\video\SDL_bmp.c" />
     <ClCompile Include="..\..\src\video\SDL_clipboard.c" />
+    <ClCompile Include="..\..\src\video\SDL_egl.c" />
     <ClCompile Include="..\..\src\video\SDL_fillrect.c" />
     <ClCompile Include="..\..\src\video\SDL_pixels.c" />
     <ClCompile Include="..\..\src\video\SDL_rect.c" />
@@ -177,6 +178,14 @@
       <CompileAsWinRT Condition="'$(Configuration)|$(Platform)'=='Debug|x64'">true</CompileAsWinRT>
       <CompileAsWinRT Condition="'$(Configuration)|$(Platform)'=='Release|x64'">true</CompileAsWinRT>
     </ClCompile>
+    <ClCompile Include="..\..\src\video\winrt\SDL_winrtopengles.cpp">
+      <CompileAsWinRT Condition="'$(Configuration)|$(Platform)'=='Debug|ARM'">true</CompileAsWinRT>
+      <CompileAsWinRT Condition="'$(Configuration)|$(Platform)'=='Release|ARM'">true</CompileAsWinRT>
+      <CompileAsWinRT Condition="'$(Configuration)|$(Platform)'=='Debug|Win32'">true</CompileAsWinRT>
+      <CompileAsWinRT Condition="'$(Configuration)|$(Platform)'=='Release|Win32'">true</CompileAsWinRT>
+      <CompileAsWinRT Condition="'$(Configuration)|$(Platform)'=='Debug|x64'">true</CompileAsWinRT>
+      <CompileAsWinRT Condition="'$(Configuration)|$(Platform)'=='Release|x64'">true</CompileAsWinRT>
+    </ClCompile>
     <ClCompile Include="..\..\src\video\winrt\SDL_winrtpointerinput.cpp">
       <CompileAsWinRT Condition="'$(Configuration)|$(Platform)'=='Debug|ARM'">true</CompileAsWinRT>
       <CompileAsWinRT Condition="'$(Configuration)|$(Platform)'=='Release|ARM'">true</CompileAsWinRT>
@@ -224,6 +233,7 @@
     <ClInclude Include="..\..\include\SDL_mouse.h" />
     <ClInclude Include="..\..\include\SDL_mutex.h" />
     <ClInclude Include="..\..\include\SDL_name.h" />
+    <ClInclude Include="..\..\include\SDL_opengles2.h" />
     <ClInclude Include="..\..\include\SDL_pixels.h" />
     <ClInclude Include="..\..\include\SDL_platform.h" />
     <ClInclude Include="..\..\include\SDL_power.h" />
@@ -299,13 +309,16 @@
     <ClInclude Include="..\..\src\video\SDL_blit_auto.h" />
     <ClInclude Include="..\..\src\video\SDL_blit_copy.h" />
     <ClInclude Include="..\..\src\video\SDL_blit_slow.h" />
+    <ClInclude Include="..\..\src\video\SDL_egl.h" />
     <ClInclude Include="..\..\src\video\SDL_pixels_c.h" />
     <ClInclude Include="..\..\src\video\SDL_rect_c.h" />
     <ClInclude Include="..\..\src\video\SDL_RLEaccel_c.h" />
     <ClInclude Include="..\..\src\video\SDL_shape_internals.h" />
     <ClInclude Include="..\..\src\video\SDL_sysvideo.h" />
+    <ClInclude Include="..\..\src\video\winrt\SDL_winrtegl.h" />
     <ClInclude Include="..\..\src\video\winrt\SDL_winrtevents_c.h" />
     <ClInclude Include="..\..\src\video\winrt\SDL_winrtmouse_c.h" />
+    <ClInclude Include="..\..\src\video\winrt\SDL_winrtopengles.h" />
     <ClInclude Include="..\..\src\video\winrt\SDL_winrtvideo_cpp.h" />
   </ItemGroup>
   <ItemGroup>
@@ -448,7 +461,7 @@
     <ClCompile>
       <PrecompiledHeader>NotUsing</PrecompiledHeader>
       <CompileAsWinRT>false</CompileAsWinRT>
-      <AdditionalIncludeDirectories>..\..\include;%(AdditionalIncludeDirectories)</AdditionalIncludeDirectories>
+      <AdditionalIncludeDirectories>..\..\include;..\..\..\angleproject\include;%(AdditionalIncludeDirectories)</AdditionalIncludeDirectories>
       <PreprocessorDefinitions>_WINDLL;_CRT_SECURE_NO_WARNINGS;%(PreprocessorDefinitions)</PreprocessorDefinitions>
     </ClCompile>
     <Link>
@@ -462,7 +475,7 @@
     <ClCompile>
       <PrecompiledHeader>NotUsing</PrecompiledHeader>
       <CompileAsWinRT>false</CompileAsWinRT>
-      <AdditionalIncludeDirectories>..\..\include;%(AdditionalIncludeDirectories)</AdditionalIncludeDirectories>
+      <AdditionalIncludeDirectories>..\..\include;..\..\..\angleproject\include;%(AdditionalIncludeDirectories)</AdditionalIncludeDirectories>
       <PreprocessorDefinitions>_WINDLL;_CRT_SECURE_NO_WARNINGS;%(PreprocessorDefinitions)</PreprocessorDefinitions>
     </ClCompile>
     <Link>
@@ -476,7 +489,7 @@
     <ClCompile>
       <PrecompiledHeader>NotUsing</PrecompiledHeader>
       <CompileAsWinRT>false</CompileAsWinRT>
-      <AdditionalIncludeDirectories>..\..\include;%(AdditionalIncludeDirectories)</AdditionalIncludeDirectories>
+      <AdditionalIncludeDirectories>..\..\include;..\..\..\angleproject\include;%(AdditionalIncludeDirectories)</AdditionalIncludeDirectories>
       <PreprocessorDefinitions>_WINDLL;_CRT_SECURE_NO_WARNINGS;%(PreprocessorDefinitions)</PreprocessorDefinitions>
     </ClCompile>
     <Link>
@@ -490,7 +503,7 @@
     <ClCompile>
       <PrecompiledHeader>NotUsing</PrecompiledHeader>
       <CompileAsWinRT>false</CompileAsWinRT>
-      <AdditionalIncludeDirectories>..\..\include;%(AdditionalIncludeDirectories)</AdditionalIncludeDirectories>
+      <AdditionalIncludeDirectories>..\..\include;..\..\..\angleproject\include;%(AdditionalIncludeDirectories)</AdditionalIncludeDirectories>
       <PreprocessorDefinitions>_WINDLL;_CRT_SECURE_NO_WARNINGS;%(PreprocessorDefinitions)</PreprocessorDefinitions>
     </ClCompile>
     <Link>
@@ -504,7 +517,7 @@
     <ClCompile>
       <PrecompiledHeader>NotUsing</PrecompiledHeader>
       <CompileAsWinRT>false</CompileAsWinRT>
-      <AdditionalIncludeDirectories>..\..\include;%(AdditionalIncludeDirectories)</AdditionalIncludeDirectories>
+      <AdditionalIncludeDirectories>..\..\include;..\..\..\angleproject\include;%(AdditionalIncludeDirectories)</AdditionalIncludeDirectories>
       <PreprocessorDefinitions>_WINDLL;_CRT_SECURE_NO_WARNINGS;%(PreprocessorDefinitions)</PreprocessorDefinitions>
     </ClCompile>
     <Link>
@@ -518,7 +531,7 @@
     <ClCompile>
       <PrecompiledHeader>NotUsing</PrecompiledHeader>
       <CompileAsWinRT>false</CompileAsWinRT>
-      <AdditionalIncludeDirectories>..\..\include;%(AdditionalIncludeDirectories)</AdditionalIncludeDirectories>
+      <AdditionalIncludeDirectories>..\..\include;..\..\..\angleproject\include;%(AdditionalIncludeDirectories)</AdditionalIncludeDirectories>
       <PreprocessorDefinitions>_WINDLL;_CRT_SECURE_NO_WARNINGS;%(PreprocessorDefinitions)</PreprocessorDefinitions>
     </ClCompile>
     <Link>

VisualC-WinRT/SDL/SDL-WinRT_VS2012.vcxproj.filters

@@ -279,6 +279,12 @@
     <ClCompile Include="..\..\src\filesystem\winrt\SDL_sysfilesystem.cpp">
       <Filter>Source Files</Filter>
     </ClCompile>
+    <ClCompile Include="..\..\src\video\SDL_egl.c">
+      <Filter>Source Files</Filter>
+    </ClCompile>
+    <ClCompile Include="..\..\src\video\winrt\SDL_winrtopengles.cpp">
+      <Filter>Source Files</Filter>
+    </ClCompile>
   </ItemGroup>
   <ItemGroup>
     <ClInclude Include="..\..\include\begin_code.h">
@@ -617,6 +623,18 @@
     <ClInclude Include="..\..\include\SDL_filesystem.h">
       <Filter>Header Files</Filter>
     </ClInclude>
+    <ClInclude Include="..\..\src\video\winrt\SDL_winrtopengles.h">
+      <Filter>Source Files</Filter>
+    </ClInclude>
+    <ClInclude Include="..\..\src\video\SDL_egl.h">
+      <Filter>Source Files</Filter>
+    </ClInclude>
+    <ClInclude Include="..\..\src\video\winrt\SDL_winrtegl.h">
+      <Filter>Source Files</Filter>
+    </ClInclude>
+    <ClInclude Include="..\..\include\SDL_opengles2.h">
+      <Filter>Header Files</Filter>
+    </ClInclude>
   </ItemGroup>
   <ItemGroup>
     <Filter Include="Header Files">

include/SDL_config_winrt.h

@@ -166,6 +166,15 @@ typedef unsigned int uintptr_t;
 #define SDL_VIDEO_DRIVER_WINRT	1
 #define SDL_VIDEO_DRIVER_DUMMY  1
 
+/* Enable OpenGL ES 2.0 (via a modified ANGLE library) */
+#if WINAPI_FAMILY != WINAPI_FAMILY_PHONE_APP    /* TODO, WinRT: try adding OpenGL ES 2 support for Windows Phone 8 */
+/* Uncomment the following two #defines to enable experimental OpenGL ES 2 support
+   (via a WinRT port of the ANGLE library).
+*/
+//#define SDL_VIDEO_OPENGL_ES2 1
+//#define SDL_VIDEO_OPENGL_EGL 1
+#endif
+
 // TODO, WinRT: Get a Direct3D 11 based renderer working in SDL.
 /* Enable appropriate renderer(s) */
 #define SDL_VIDEO_RENDER_D3D11  1

include/SDL_opengles2.h

@@ -33,6 +33,8 @@
 #include <GLES2/gl2ext.h>
 #endif
 
+#ifndef __WINRT__
 #ifndef APIENTRY
 #define APIENTRY
 #endif
+#endif

src/video/SDL_egl.c

@@ -40,6 +40,13 @@
 #define DEFAULT_OGL_ES_PVR "libGLES_CM.so"
 #define DEFAULT_OGL_ES "libGLESv1_CM.so"
 
+#elif SDL_VIDEO_DRIVER_WINRT
+/* WinRT (via a modified version of Google's ANGLE library) */
+#define DEFAULT_EGL "libEGL.dll"
+#define DEFAULT_OGL_ES2 "libGLESv2.dll"
+#define DEFAULT_OGL_ES_PVR NULL
+#define DEFAULT_OGL_ES NULL
+
 #else
 /* Desktop Linux */
 #define DEFAULT_EGL "libEGL.so.1"
@@ -134,8 +141,13 @@ SDL_EGL_LoadLibrary(_THIS, const char *egl_path, NativeDisplayType native_displa
 #endif
 
     /* A funny thing, loading EGL.so first does not work on the Raspberry, so we load libGL* first */
+#ifdef __WINRT__
+    path = NULL;
+    egl_dll_handle = NULL;
+#else
     path = getenv("SDL_VIDEO_GL_DRIVER");
     egl_dll_handle = dlopen(path, dlopen_flags);
+#endif
     if ((path == NULL) | (egl_dll_handle == NULL)) {
         if (_this->gl_config.major_version > 1) {
             path = DEFAULT_OGL_ES2;
@@ -160,7 +172,11 @@ SDL_EGL_LoadLibrary(_THIS, const char *egl_path, NativeDisplayType native_displa
     /* Catch the case where the application isn't linked with EGL */
     if ((dlsym(dll_handle, "eglChooseConfig") == NULL) && (egl_path == NULL)) {
         dlclose(dll_handle);
+#ifdef __WINRT__
+        path = NULL;
+#else
         path = getenv("SDL_VIDEO_EGL_DRIVER");
+#endif
         if (path == NULL) {
             path = DEFAULT_EGL;
         }

src/video/SDL_egl.h

@@ -25,6 +25,18 @@
 
 #if SDL_VIDEO_OPENGL_EGL
 
+#if defined(__WINRT__)
+
+// DavidL: including this here leads to a compiler error:
+// C2016: C requires that a struct or union has at least one member
+// The error originates from a WinRT header file itself, roapi.h.
+//
+// Instead of including that file (EGL/egl.h), a subset of its contents is
+// made available as part of winrt/SDL_winrtegl.h
+//#include <EGL/egl.h>
+#include "winrt/SDL_winrtegl.h"
+
+#else
 #include <EGL/egl.h>
 
 #include <dlfcn.h>
@@ -32,6 +44,8 @@
 #define dlsym(x,y) dlsym(x, "_" y)
 #endif
 
+#endif /* ! defined(__WINRT__) */
+
 #include "SDL_sysvideo.h"
 
 typedef struct SDL_EGL_VideoData
@@ -41,46 +55,46 @@ typedef struct SDL_EGL_VideoData
     EGLConfig egl_config;
     int egl_swapinterval;
     
-    EGLDisplay(*eglGetDisplay) (NativeDisplayType display);
+    EGLDisplay(EGLAPIENTRY *eglGetDisplay) (NativeDisplayType display);
-    EGLBoolean(*eglInitialize) (EGLDisplay dpy, EGLint * major,
+    EGLBoolean(EGLAPIENTRY *eglInitialize) (EGLDisplay dpy, EGLint * major,
-                                EGLint * minor);
+                                            EGLint * minor);
-    EGLBoolean(*eglTerminate) (EGLDisplay dpy);
+    EGLBoolean(EGLAPIENTRY *eglTerminate) (EGLDisplay dpy);
     
-    void *(*eglGetProcAddress) (const char * procName);
+    void *(EGLAPIENTRY *eglGetProcAddress) (const char * procName);
     
-    EGLBoolean(*eglChooseConfig) (EGLDisplay dpy,
+    EGLBoolean(EGLAPIENTRY *eglChooseConfig) (EGLDisplay dpy,
-                                  const EGLint * attrib_list,
+                                              const EGLint * attrib_list,
-                                  EGLConfig * configs,
+                                              EGLConfig * configs,
-                                  EGLint config_size, EGLint * num_config);
+                                              EGLint config_size, EGLint * num_config);
     
-    EGLContext(*eglCreateContext) (EGLDisplay dpy,
+    EGLContext(EGLAPIENTRY *eglCreateContext) (EGLDisplay dpy,
-                                   EGLConfig config,
+                                               EGLConfig config,
-                                   EGLContext share_list,
+                                               EGLContext share_list,
-                                   const EGLint * attrib_list);
+                                               const EGLint * attrib_list);
     
-    EGLBoolean(*eglDestroyContext) (EGLDisplay dpy, EGLContext ctx);
+    EGLBoolean(EGLAPIENTRY *eglDestroyContext) (EGLDisplay dpy, EGLContext ctx);
     
-    EGLSurface(*eglCreateWindowSurface) (EGLDisplay dpy,
+    EGLSurface(EGLAPIENTRY *eglCreateWindowSurface) (EGLDisplay dpy,
-                                         EGLConfig config,
+                                                     EGLConfig config,
-                                         NativeWindowType window,
+                                                     NativeWindowType window,
-                                         const EGLint * attrib_list);
+                                                     const EGLint * attrib_list);
-    EGLBoolean(*eglDestroySurface) (EGLDisplay dpy, EGLSurface surface);
+    EGLBoolean(EGLAPIENTRY *eglDestroySurface) (EGLDisplay dpy, EGLSurface surface);
     
-    EGLBoolean(*eglMakeCurrent) (EGLDisplay dpy, EGLSurface draw,
+    EGLBoolean(EGLAPIENTRY *eglMakeCurrent) (EGLDisplay dpy, EGLSurface draw,
-                                 EGLSurface read, EGLContext ctx);
+                                             EGLSurface read, EGLContext ctx);
     
-    EGLBoolean(*eglSwapBuffers) (EGLDisplay dpy, EGLSurface draw);
+    EGLBoolean(EGLAPIENTRY *eglSwapBuffers) (EGLDisplay dpy, EGLSurface draw);
     
-    EGLBoolean(*eglSwapInterval) (EGLDisplay dpy, EGLint interval);
+    EGLBoolean(EGLAPIENTRY *eglSwapInterval) (EGLDisplay dpy, EGLint interval);
     
-    const char *(*eglQueryString) (EGLDisplay dpy, EGLint name);
+    const char *(EGLAPIENTRY *eglQueryString) (EGLDisplay dpy, EGLint name);
     
-    EGLBoolean(*eglGetConfigAttrib) (EGLDisplay dpy, EGLConfig config,
+    EGLBoolean(EGLAPIENTRY *eglGetConfigAttrib) (EGLDisplay dpy, EGLConfig config,
-                                     EGLint attribute, EGLint * value);
+                                                 EGLint attribute, EGLint * value);
     
-    EGLBoolean(*eglWaitNative) (EGLint  engine);
+    EGLBoolean(EGLAPIENTRY *eglWaitNative) (EGLint  engine);
 
-    EGLBoolean(*eglWaitGL)(void);   
+    EGLBoolean(EGLAPIENTRY *eglWaitGL)(void);   
 } SDL_EGL_VideoData;
 
 /* OpenGLES functions */

src/video/SDL_video.c

@@ -41,7 +41,7 @@
 
 /* GL and GLES2 headers conflict on Linux 32 bits */
 #if SDL_VIDEO_OPENGL_ES2 && !SDL_VIDEO_OPENGL
-#include "SDL_opengles2.h"
+#include "SDL_opengles2.h" 
 #endif /* SDL_VIDEO_OPENGL_ES2 && !SDL_VIDEO_OPENGL */
 
 #include "SDL_syswm.h"

src/video/winrt/SDL_winrtegl.h

@@ -0,0 +1,166 @@
+/*
+  Simple DirectMedia Layer
+  Copyright (C) 1997-2013 Sam Lantinga <slouken@libsdl.org>
+
+  This software is provided 'as-is', without any express or implied
+  warranty.  In no event will the authors be held liable for any damages
+  arising from the use of this software.
+
+  Permission is granted to anyone to use this software for any purpose,
+  including commercial applications, and to alter it and redistribute it
+  freely, subject to the following restrictions:
+
+  1. The origin of this software must not be misrepresented; you must not
+     claim that you wrote the original software. If you use this software
+     in a product, an acknowledgment in the product documentation would be
+     appreciated but is not required.
+  2. Altered source versions must be plainly marked as such, and must not be
+     misrepresented as being the original software.
+  3. This notice may not be removed or altered from any source distribution.
+*/
+
+#include "SDL_config.h"
+
+#ifndef _SDL_winrtegl_h
+#define _SDL_winrtegl_h
+
+#include "SDL_hints.h"
+#include "SDL_loadso.h"
+
+#if SDL_VIDEO_DRIVER_WINRT && SDL_VIDEO_OPENGL_EGL
+
+/* Emulate various *nix functions that SDL_egl.c will call.
+ */
+#define dlsym SDL_LoadFunction
+#define dlclose SDL_UnloadObject
+#define dlopen(path, mode) ((path == NULL) ? NULL : SDL_LoadObject(path))  /* TODO, WinRT: create a separate function here, that sets dlerror on empty params */
+#define dlerror SDL_GetError
+#define getenv SDL_GetHint
+#define RTLD_LAZY 0
+
+
+/*
+** Copyright (c) 2007-2009 The Khronos Group Inc.
+**
+** Permission is hereby granted, free of charge, to any person obtaining a
+** copy of this software and/or associated documentation files (the
+** "Materials"), to deal in the Materials without restriction, including
+** without limitation the rights to use, copy, modify, merge, publish,
+** distribute, sublicense, and/or sell copies of the Materials, and to
+** permit persons to whom the Materials are furnished to do so, subject to
+** the following conditions:
+**
+** The above copyright notice and this permission notice shall be included
+** in all copies or substantial portions of the Materials.
+**
+** THE MATERIALS ARE PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+** EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+** MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
+** IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
+** CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
+** TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
+** MATERIALS OR THE USE OR OTHER DEALINGS IN THE MATERIALS.
+*/
+
+/* EGL Types */
+/* EGLint is defined in eglplatform.h */
+typedef unsigned int EGLBoolean;
+typedef unsigned int EGLenum;
+typedef void *EGLConfig;
+typedef void *EGLContext;
+typedef void *EGLDisplay;
+typedef void *EGLSurface;
+typedef void *EGLClientBuffer;
+
+/* Platform-specific types */
+//typedef int EGLNativeDisplayType;
+typedef int NativeDisplayType;
+typedef void * NativeWindowType;
+
+#ifndef EGLAPIENTRY
+#define EGLAPIENTRY  __stdcall
+#endif
+
+
+/* Define EGLint. This must be a signed integral type large enough to contain
+ * all legal attribute names and values passed into and out of EGL, whether
+ * their type is boolean, bitmask, enumerant (symbolic constant), integer,
+ * handle, or other.  While in general a 32-bit integer will suffice, if
+ * handles are 64 bit types, then EGLint should be defined as a signed 64-bit
+ * integer type.
+ */
+typedef int EGLint;
+
+/* EGL Enumerants. Bitmasks and other exceptional cases aside, most
+ * enums are assigned unique values starting at 0x3000.
+ */
+
+/* EGL aliases */
+#define EGL_FALSE			0
+#define EGL_TRUE			1
+
+/* Out-of-band handle values */
+#define EGL_DEFAULT_DISPLAY		((EGLNativeDisplayType)0)
+#define EGL_NO_CONTEXT			((EGLContext)0)
+#define EGL_NO_DISPLAY			((EGLDisplay)0)
+#define EGL_NO_SURFACE			((EGLSurface)0)
+
+/* Config attributes */
+#define EGL_BUFFER_SIZE			0x3020
+#define EGL_ALPHA_SIZE			0x3021
+#define EGL_BLUE_SIZE			0x3022
+#define EGL_GREEN_SIZE			0x3023
+#define EGL_RED_SIZE			0x3024
+#define EGL_DEPTH_SIZE			0x3025
+#define EGL_STENCIL_SIZE		0x3026
+#define EGL_CONFIG_CAVEAT		0x3027
+#define EGL_CONFIG_ID			0x3028
+#define EGL_LEVEL			0x3029
+#define EGL_MAX_PBUFFER_HEIGHT		0x302A
+#define EGL_MAX_PBUFFER_PIXELS		0x302B
+#define EGL_MAX_PBUFFER_WIDTH		0x302C
+#define EGL_NATIVE_RENDERABLE		0x302D
+#define EGL_NATIVE_VISUAL_ID		0x302E
+#define EGL_NATIVE_VISUAL_TYPE		0x302F
+#define EGL_SAMPLES			0x3031
+#define EGL_SAMPLE_BUFFERS		0x3032
+#define EGL_SURFACE_TYPE		0x3033
+#define EGL_TRANSPARENT_TYPE		0x3034
+#define EGL_TRANSPARENT_BLUE_VALUE	0x3035
+#define EGL_TRANSPARENT_GREEN_VALUE	0x3036
+#define EGL_TRANSPARENT_RED_VALUE	0x3037
+#define EGL_NONE			0x3038	/* Attrib list terminator */
+#define EGL_BIND_TO_TEXTURE_RGB		0x3039
+#define EGL_BIND_TO_TEXTURE_RGBA	0x303A
+#define EGL_MIN_SWAP_INTERVAL		0x303B
+#define EGL_MAX_SWAP_INTERVAL		0x303C
+#define EGL_LUMINANCE_SIZE		0x303D
+#define EGL_ALPHA_MASK_SIZE		0x303E
+#define EGL_COLOR_BUFFER_TYPE		0x303F
+#define EGL_RENDERABLE_TYPE		0x3040
+#define EGL_MATCH_NATIVE_PIXMAP		0x3041	/* Pseudo-attribute (not queryable) */
+#define EGL_CONFORMANT			0x3042
+
+/* Config attribute mask bits */
+#define EGL_PBUFFER_BIT			0x0001	/* EGL_SURFACE_TYPE mask bits */
+#define EGL_PIXMAP_BIT			0x0002	/* EGL_SURFACE_TYPE mask bits */
+#define EGL_WINDOW_BIT			0x0004	/* EGL_SURFACE_TYPE mask bits */
+#define EGL_VG_COLORSPACE_LINEAR_BIT	0x0020	/* EGL_SURFACE_TYPE mask bits */
+#define EGL_VG_ALPHA_FORMAT_PRE_BIT	0x0040	/* EGL_SURFACE_TYPE mask bits */
+#define EGL_MULTISAMPLE_RESOLVE_BOX_BIT 0x0200	/* EGL_SURFACE_TYPE mask bits */
+#define EGL_SWAP_BEHAVIOR_PRESERVED_BIT 0x0400	/* EGL_SURFACE_TYPE mask bits */
+
+#define EGL_OPENGL_ES_BIT		0x0001	/* EGL_RENDERABLE_TYPE mask bits */
+#define EGL_OPENVG_BIT			0x0002	/* EGL_RENDERABLE_TYPE mask bits */
+#define EGL_OPENGL_ES2_BIT		0x0004	/* EGL_RENDERABLE_TYPE mask bits */
+#define EGL_OPENGL_BIT			0x0008	/* EGL_RENDERABLE_TYPE mask bits */
+
+/* CreateContext attributes */
+#define EGL_CONTEXT_CLIENT_VERSION	0x3098
+
+
+#endif /* SDL_VIDEO_DRIVER_WINRT && SDL_VIDEO_OPENGL_EGL */
+
+#endif /* _SDL_winrtegl_h */
+
+/* vi: set ts=4 sw=4 expandtab: */

src/video/winrt/SDL_winrtopengles.cpp

@@ -0,0 +1,55 @@
+/*
+  Simple DirectMedia Layer
+  Copyright (C) 1997-2013 Sam Lantinga <slouken@libsdl.org>
+
+  This software is provided 'as-is', without any express or implied
+  warranty.  In no event will the authors be held liable for any damages
+  arising from the use of this software.
+
+  Permission is granted to anyone to use this software for any purpose,
+  including commercial applications, and to alter it and redistribute it
+  freely, subject to the following restrictions:
+
+  1. The origin of this software must not be misrepresented; you must not
+     claim that you wrote the original software. If you use this software
+     in a product, an acknowledgment in the product documentation would be
+     appreciated but is not required.
+  2. Altered source versions must be plainly marked as such, and must not be
+     misrepresented as being the original software.
+  3. This notice may not be removed or altered from any source distribution.
+*/
+#include "SDL_config.h"
+
+// TODO: WinRT, make this file compile via C code
+
+#if SDL_VIDEO_DRIVER_WINRT && SDL_VIDEO_OPENGL_EGL
+
+/* EGL implementation of SDL OpenGL support */
+
+// TODO, WinRT: Try to include these here, or via something else (rather than redefining key parts of them)
+//#include <GLES2/gl2.h>
+//#include <EGL/egl.h>
+//#include <EGL/eglext.h>
+
+#include "SDL_winrtvideo_cpp.h"
+extern "C" {
+#include "SDL_winrtopengles.h"
+}
+
+#define EGL_D3D11_ONLY_DISPLAY_ANGLE ((NativeDisplayType) -3)
+
+extern "C" int
+WINRT_GLES_LoadLibrary(_THIS, const char *path) {
+    return SDL_EGL_LoadLibrary(_this, path, EGL_D3D11_ONLY_DISPLAY_ANGLE);
+}
+
+extern "C" {
+SDL_EGL_CreateContext_impl(WINRT)
+SDL_EGL_SwapWindow_impl(WINRT)
+SDL_EGL_MakeCurrent_impl(WINRT)
+}
+
+#endif /* SDL_VIDEO_DRIVER_WINRT && SDL_VIDEO_OPENGL_EGL */
+
+/* vi: set ts=4 sw=4 expandtab: */
+

src/video/winrt/SDL_winrtopengles.h

@@ -0,0 +1,48 @@
+/*
+  Simple DirectMedia Layer
+  Copyright (C) 1997-2013 Sam Lantinga <slouken@libsdl.org>
+
+  This software is provided 'as-is', without any express or implied
+  warranty.  In no event will the authors be held liable for any damages
+  arising from the use of this software.
+
+  Permission is granted to anyone to use this software for any purpose,
+  including commercial applications, and to alter it and redistribute it
+  freely, subject to the following restrictions:
+
+  1. The origin of this software must not be misrepresented; you must not
+     claim that you wrote the original software. If you use this software
+     in a product, an acknowledgment in the product documentation would be
+     appreciated but is not required.
+  2. Altered source versions must be plainly marked as such, and must not be
+     misrepresented as being the original software.
+  3. This notice may not be removed or altered from any source distribution.
+*/
+#include "SDL_config.h"
+
+#ifndef _SDL_winrtopengles_h
+#define _SDL_winrtopengles_h
+
+#if SDL_VIDEO_DRIVER_WINRT && SDL_VIDEO_OPENGL_EGL
+
+#include "../SDL_sysvideo.h"
+#include "../SDL_egl.h"
+
+/* OpenGLES functions */
+#define WINRT_GLES_GetAttribute SDL_EGL_GetAttribute
+#define WINRT_GLES_GetProcAddress SDL_EGL_GetProcAddress
+#define WINRT_GLES_UnloadLibrary SDL_EGL_UnloadLibrary
+#define WINRT_GLES_SetSwapInterval SDL_EGL_SetSwapInterval
+#define WINRT_GLES_GetSwapInterval SDL_EGL_GetSwapInterval
+#define WINRT_GLES_DeleteContext SDL_EGL_DeleteContext
+
+extern int WINRT_GLES_LoadLibrary(_THIS, const char *path);
+extern SDL_GLContext WINRT_GLES_CreateContext(_THIS, SDL_Window * window);
+extern void WINRT_GLES_SwapWindow(_THIS, SDL_Window * window);
+extern int WINRT_GLES_MakeCurrent(_THIS, SDL_Window * window, SDL_GLContext context);
+
+#endif /* SDL_VIDEO_DRIVER_WINRT && SDL_VIDEO_OPENGL_EGL */
+
+#endif /* _SDL_winrtopengles_h */
+
+/* vi: set ts=4 sw=4 expandtab: */

src/video/winrt/SDL_winrtvideo.cpp

@@ -42,6 +42,7 @@ extern "C" {
 #include "../../events/SDL_events_c.h"
 #include "../../render/SDL_sysrender.h"
 #include "SDL_syswm.h"
+#include "SDL_winrtopengles.h"
 }
 
 #include "../../core/winrt/SDL_winrtapp_direct3d.h"
@@ -111,6 +112,17 @@ WINRT_CreateDevice(int devindex)
     device->SetDisplayMode = WINRT_SetDisplayMode;
     device->PumpEvents = WINRT_PumpEvents;
     device->GetWindowWMInfo = WINRT_GetWindowWMInfo;
+#ifdef SDL_VIDEO_OPENGL_EGL
+    device->GL_LoadLibrary = WINRT_GLES_LoadLibrary;
+    device->GL_GetProcAddress = WINRT_GLES_GetProcAddress;
+    device->GL_UnloadLibrary = WINRT_GLES_UnloadLibrary;
+    device->GL_CreateContext = WINRT_GLES_CreateContext;
+    device->GL_MakeCurrent = WINRT_GLES_MakeCurrent;
+    device->GL_SetSwapInterval = WINRT_GLES_SetSwapInterval;
+    device->GL_GetSwapInterval = WINRT_GLES_GetSwapInterval;
+    device->GL_SwapWindow = WINRT_GLES_SwapWindow;
+    device->GL_DeleteContext = WINRT_GLES_DeleteContext;
+#endif
     device->free = WINRT_DeleteDevice;
     WINRT_GlobalSDLVideoDevice = device;
 
@@ -247,6 +259,22 @@ WINRT_CreateWindow(_THIS, SDL_Window * window)
         data->coreWindow = CoreWindow::GetForCurrentThread();
     }
 
+#if SDL_VIDEO_OPENGL_EGL
+    /* Setup the EGL surface, but only if OpenGL ES 2 was requested. */
+    if (!(window->flags & SDL_WINDOW_OPENGL)) {
+        /* OpenGL ES 2 wasn't requested.  Don't set up an EGL surface. */
+        data->egl_surface = EGL_NO_SURFACE;
+    } else {
+        /* OpenGL ES 2 was reuqested.  Set up an EGL surface. */
+        IUnknown * nativeWindow = reinterpret_cast<IUnknown *>(data->coreWindow.Get());
+        data->egl_surface = SDL_EGL_CreateSurface(_this, nativeWindow);
+        if (data->egl_surface == NULL) {
+            // TODO, WinRT: see if SDL_EGL_CreateSurface, or its callee(s), sets an error message.  If so, attach it to the SDL error.
+            return SDL_SetError("SDL_EGL_CreateSurface failed");
+        }
+    }
+#endif
+
     /* Make sure the window is considered to be positioned at {0,0},
        and is considered fullscreen, shown, and the like.
     */
@@ -259,6 +287,12 @@ WINRT_CreateWindow(_THIS, SDL_Window * window)
         SDL_WINDOW_MAXIMIZED |
         SDL_WINDOW_INPUT_GRABBED;
 
+#if SDL_VIDEO_OPENGL_EGL
+    if (data->egl_surface) {
+        window->flags |= SDL_WINDOW_OPENGL;
+    }
+#endif
+
     /* WinRT does not, as of this writing, appear to support app-adjustable
        window sizes.  Set the window size to whatever the native WinRT
        CoreWindow is set at.

src/video/winrt/SDL_winrtvideo_cpp.h

@@ -26,8 +26,14 @@
 #endif
 
 /* SDL includes: */
+#include "SDL_video.h"
 #include "SDL_events.h"
 
+extern "C" {
+#include "../SDL_sysvideo.h"
+#include "SDL_winrtegl.h"
+}
+
 
 /* The global, WinRT, SDL Window.
    For now, SDL/WinRT only supports one window (due to platform limitations of
@@ -49,6 +55,9 @@ struct SDL_WindowData
 {
     SDL_Window *sdlWindow;
     Platform::Agile<Windows::UI::Core::CoreWindow> coreWindow;
+#ifdef SDL_VIDEO_OPENGL_EGL
+    EGLSurface egl_surface;
+#endif
 };
 
 #endif // ifdef __cplusplus_winrt