EGL: Add support for EGL_ANGLE_platform_angle

This adds basic support for selecting the platform type (rendering backend) when running on ANGLE. Related to #1380.
glfw · Jun 28, 2020 · 0dea8a4 · 0dea8a4
1 parent e6a6a99
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diff --git a/README.md b/README.md
@@ -126,6 +126,8 @@ information on what to include when reporting a bug.
  - Added `GLFW_POINTING_HAND_CURSOR` alias for `GLFW_HAND_CURSOR` (#427)
  - Added `GLFW_FEATURE_UNAVAILABLE` error for platform limitations (#1692)
  - Added `GLFW_FEATURE_UNIMPLEMENTED` error for incomplete backends (#1692)
+ - Added `GLFW_ANGLE_PLATFORM_TYPE` init hint and `GLFW_ANGLE_PLATFORM_TYPE_*`
+   values to select ANGLE backend (#1380)
  - Updated the minimum required CMake version to 3.1
  - Disabled tests and examples by default when built as a CMake subdirectory
  - Bugfix: The CMake config-file package used an absolute path and was not
@@ -195,6 +197,8 @@ information on what to include when reporting a bug.
    macOS versions (#1442)
  - [NSGL] Bugfix: Workaround for swap interval on 10.14 broke on 10.12 (#1483)
  - [EGL] Added platform selection via the `EGL_EXT_platform_base` extension
+ - [EGL] Added ANGLE backend selection via `EGL_ANGLE_platform_angle` extension
+   (#1380)
 
 
 ## Contact

diff --git a/docs/intro.dox b/docs/intro.dox
@@ -93,6 +93,18 @@ __GLFW_JOYSTICK_HAT_BUTTONS__ specifies whether to also expose joystick hats as
 buttons, for compatibility with earlier versions of GLFW that did not have @ref
 glfwGetJoystickHats.  Set this with @ref glfwInitHint.
 
+@anchor GLFW_ANGLE_PLATFORM_TYPE_hint
+__GLFW_ANGLE_PLATFORM_TYPE__ specifies the platform type (rendering backend) to
+request when using OpenGL ES and EGL via
+[ANGLE](https://chromium.googlesource.com/angle/angle/).  If the requested
+platform type is unavailable, ANGLE will use its default.  Set this hint with
+@ref glfwInitHint.
+
+@par
+The ANGLE platform type is specified via the `EGL_ANGLE_platform_angle`
+extension.  This extension is not used if this hint is
+`GLFW_ANGLE_PLATFORM_TYPE_NONE`, which is the default value.
+
 
 @subsubsection init_hints_osx macOS specific init hints
 
@@ -109,11 +121,12 @@ a nib or manually by GLFW.  Set this with @ref glfwInitHint.
 
 @subsubsection init_hints_values Supported and default values
 
-Initialization hint             | Default value | Supported values
-------------------------------- | ------------- | ----------------
-@ref GLFW_JOYSTICK_HAT_BUTTONS  | `GLFW_TRUE`   | `GLFW_TRUE` or `GLFW_FALSE`
-@ref GLFW_COCOA_CHDIR_RESOURCES | `GLFW_TRUE`   | `GLFW_TRUE` or `GLFW_FALSE`
-@ref GLFW_COCOA_MENUBAR         | `GLFW_TRUE`   | `GLFW_TRUE` or `GLFW_FALSE`
+Initialization hint             | Default value                   | Supported values
+------------------------------- | ------------------------------- | ----------------
+@ref GLFW_JOYSTICK_HAT_BUTTONS  | `GLFW_TRUE`                     | `GLFW_TRUE` or `GLFW_FALSE`
+@ref GLFW_ANGLE_PLATFORM_TYPE   | `GLFW_ANGLE_PLATFORM_TYPE_NONE` | `GLFW_ANGLE_PLATFORM_TYPE_NONE`, `GLFW_ANGLE_PLATFORM_TYPE_OPENGL`, `GLFW_ANGLE_PLATFORM_TYPE_OPENGLES`, `GLFW_ANGLE_PLATFORM_TYPE_D3D9`, `GLFW_ANGLE_PLATFORM_TYPE_D3D11`, `GLFW_ANGLE_PLATFORM_TYPE_VULKAN` or `GLFW_ANGLE_PLATFORM_TYPE_METAL`
+@ref GLFW_COCOA_CHDIR_RESOURCES | `GLFW_TRUE`                     | `GLFW_TRUE` or `GLFW_FALSE`
+@ref GLFW_COCOA_MENUBAR         | `GLFW_TRUE`                     | `GLFW_TRUE` or `GLFW_FALSE`
 
 
 @subsection intro_init_terminate Terminating GLFW

diff --git a/docs/news.dox b/docs/news.dox
@@ -27,6 +27,15 @@ are still available.
 For more information see @ref cursor_standard.
 
 
+@subsubsection features_34_angle_backend Support for ANGLE rendering backend selection
+
+GLFW now provides the
+[GLFW_ANGLE_PLATFORM_TYPE](@ref GLFW_ANGLE_PLATFORM_TYPE_hint) init hint for
+requesting a specific rendering backend when using
+[ANGLE](https://chromium.googlesource.com/angle/angle/) to create OpenGL ES
+contexts.
+
+
 @subsubsection features_34_win32_keymenu Support for keyboard access to Windows window menu
 
 GLFW now provides the
@@ -94,6 +103,14 @@ then GLFW will fail to initialize.
  - @ref GLFW_CONTEXT_DEBUG
  - @ref GLFW_FEATURE_UNAVAILABLE
  - @ref GLFW_FEATURE_UNIMPLEMENTED
+ - @ref GLFW_ANGLE_PLATFORM_TYPE
+ - @ref GLFW_ANGLE_PLATFORM_TYPE_NONE
+ - @ref GLFW_ANGLE_PLATFORM_TYPE_OPENGL
+ - @ref GLFW_ANGLE_PLATFORM_TYPE_OPENGLES
+ - @ref GLFW_ANGLE_PLATFORM_TYPE_D3D9
+ - @ref GLFW_ANGLE_PLATFORM_TYPE_D3D11
+ - @ref GLFW_ANGLE_PLATFORM_TYPE_VULKAN
+ - @ref GLFW_ANGLE_PLATFORM_TYPE_METAL
 
 
 @section news_archive Release notes for earlier versions

diff --git a/include/GLFW/glfw3.h b/include/GLFW/glfw3.h
@@ -1104,6 +1104,14 @@ extern "C" {
 #define GLFW_EGL_CONTEXT_API        0x00036002
 #define GLFW_OSMESA_CONTEXT_API     0x00036003
 
+#define GLFW_ANGLE_PLATFORM_TYPE_NONE    0x00037001
+#define GLFW_ANGLE_PLATFORM_TYPE_OPENGL  0x00037002
+#define GLFW_ANGLE_PLATFORM_TYPE_OPENGLES 0x00037003
+#define GLFW_ANGLE_PLATFORM_TYPE_D3D9    0x00037004
+#define GLFW_ANGLE_PLATFORM_TYPE_D3D11   0x00037005
+#define GLFW_ANGLE_PLATFORM_TYPE_VULKAN  0x00037007
+#define GLFW_ANGLE_PLATFORM_TYPE_METAL   0x00037008
+
 /*! @defgroup shapes Standard cursor shapes
  *  @brief Standard system cursor shapes.
  *
@@ -1220,6 +1228,11 @@ extern "C" {
  *  Joystick hat buttons [init hint](@ref GLFW_JOYSTICK_HAT_BUTTONS).
  */
 #define GLFW_JOYSTICK_HAT_BUTTONS   0x00050001
+/*! @brief ANGLE rendering backend init hint.
+ *
+ *  ANGLE rendering backend [init hint](@ref GLFW_ANGLE_PLATFORM_TYPE_hint).
+ */
+#define GLFW_ANGLE_PLATFORM_TYPE    0x00050002
 /*! @brief macOS specific init hint.
  *
  *  macOS specific [init hint](@ref GLFW_COCOA_CHDIR_RESOURCES_hint).

diff --git a/src/cocoa_window.m b/src/cocoa_window.m
@@ -1721,8 +1721,34 @@ void _glfwPlatformSetClipboardString(const char* string)
     } // autoreleasepool
 }
 
-EGLenum _glfwPlatformGetEGLPlatform(void)
+EGLenum _glfwPlatformGetEGLPlatform(EGLint** attribs)
 {
+    if (_glfw.egl.ANGLE_platform_angle)
+    {
+        int type = 0;
+
+        if (_glfw.egl.ANGLE_platform_angle_opengl)
+        {
+            if (_glfw.hints.init.angleType == GLFW_ANGLE_PLATFORM_TYPE_OPENGL)
+                type = EGL_PLATFORM_ANGLE_TYPE_OPENGL_ANGLE;
+        }
+
+        if (_glfw.egl.ANGLE_platform_angle_metal)
+        {
+            if (_glfw.hints.init.angleType == GLFW_ANGLE_PLATFORM_TYPE_METAL)
+                type = EGL_PLATFORM_ANGLE_TYPE_METAL_ANGLE;
+        }
+
+        if (type)
+        {
+            *attribs = calloc(3, sizeof(EGLint));
+            (*attribs)[0] = EGL_PLATFORM_ANGLE_TYPE_ANGLE;
+            (*attribs)[1] = type;
+            (*attribs)[2] = EGL_NONE;
+            return EGL_PLATFORM_ANGLE_ANGLE;
+        }
+    }
+
     return 0;
 }
 

diff --git a/src/egl_context.c b/src/egl_context.c
@@ -303,6 +303,7 @@ static void destroyContextEGL(_GLFWwindow* window)
 GLFWbool _glfwInitEGL(void)
 {
     int i;
+    EGLint* attribs = NULL;
     const char* extensions;
     const char* sonames[] =
     {
@@ -408,6 +409,16 @@ GLFWbool _glfwInitEGL(void)
             _glfwStringInExtensionString("EGL_EXT_platform_x11", extensions);
         _glfw.egl.EXT_platform_wayland =
             _glfwStringInExtensionString("EGL_EXT_platform_wayland", extensions);
+        _glfw.egl.ANGLE_platform_angle =
+            _glfwStringInExtensionString("EGL_ANGLE_platform_angle", extensions);
+        _glfw.egl.ANGLE_platform_angle_opengl =
+            _glfwStringInExtensionString("EGL_ANGLE_platform_angle_opengl", extensions);
+        _glfw.egl.ANGLE_platform_angle_d3d =
+            _glfwStringInExtensionString("EGL_ANGLE_platform_angle_d3d", extensions);
+        _glfw.egl.ANGLE_platform_angle_vulkan =
+            _glfwStringInExtensionString("EGL_ANGLE_platform_angle_vulkan", extensions);
+        _glfw.egl.ANGLE_platform_angle_metal =
+            _glfwStringInExtensionString("EGL_ANGLE_platform_angle_metal", extensions);
     }
 
     if (_glfw.egl.EXT_platform_base)
@@ -418,17 +429,19 @@ GLFWbool _glfwInitEGL(void)
             eglGetProcAddress("eglCreatePlatformWindowSurfaceEXT");
     }
 
-    _glfw.egl.platform = _glfwPlatformGetEGLPlatform();
+    _glfw.egl.platform = _glfwPlatformGetEGLPlatform(&attribs);
     if (_glfw.egl.platform)
     {
         _glfw.egl.display =
             eglGetPlatformDisplayEXT(_glfw.egl.platform,
                                      _glfwPlatformGetEGLNativeDisplay(),
-                                     NULL);
+                                     attribs);
     }
     else
         _glfw.egl.display = eglGetDisplay(_glfwPlatformGetEGLNativeDisplay());
 
+    free(attribs);
+
     if (_glfw.egl.display == EGL_NO_DISPLAY)
     {
         _glfwInputError(GLFW_API_UNAVAILABLE,
@@ -633,7 +646,9 @@ GLFWbool _glfwCreateContextEGL(_GLFWwindow* window,
     setAttrib(EGL_NONE, EGL_NONE);
 
     native = _glfwPlatformGetEGLNativeWindow(window);
-    if (_glfw.egl.platform)
+    // HACK: ANGLE does not implement eglCreatePlatformWindowSurfaceEXT
+    //       despite reporting EGL_EXT_platform_base
+    if (_glfw.egl.platform && _glfw.egl.platform != EGL_PLATFORM_ANGLE_ANGLE)
     {
         window->context.egl.surface =
             eglCreatePlatformWindowSurfaceEXT(_glfw.egl.display, config, native, attribs);

diff --git a/src/egl_context.h b/src/egl_context.h
@@ -92,6 +92,15 @@
 #define EGL_CONTEXT_RELEASE_BEHAVIOR_FLUSH_KHR 0x2098
 #define EGL_PLATFORM_X11_EXT 0x31d5
 #define EGL_PLATFORM_WAYLAND_EXT 0x31d8
+#define EGL_PLATFORM_ANGLE_ANGLE 0x3202
+#define EGL_PLATFORM_ANGLE_TYPE_ANGLE 0x3203
+#define EGL_PLATFORM_ANGLE_TYPE_OPENGL_ANGLE 0x320d
+#define EGL_PLATFORM_ANGLE_TYPE_OPENGLES_ANGLE 0x320e
+#define EGL_PLATFORM_ANGLE_TYPE_D3D9_ANGLE 0x3207
+#define EGL_PLATFORM_ANGLE_TYPE_D3D11_ANGLE 0x3208
+#define EGL_PLATFORM_ANGLE_TYPE_VULKAN_ANGLE 0x3450
+#define EGL_PLATFORM_ANGLE_TYPE_METAL_ANGLE 0x3489
+#define EGL_PLATFORM_ANGLE_NATIVE_PLATFORM_TYPE_ANGLE 0x348f
 
 typedef int EGLint;
 typedef unsigned int EGLBoolean;
@@ -173,6 +182,11 @@ typedef struct _GLFWlibraryEGL
     GLFWbool        EXT_platform_base;
     GLFWbool        EXT_platform_x11;
     GLFWbool        EXT_platform_wayland;
+    GLFWbool        ANGLE_platform_angle;
+    GLFWbool        ANGLE_platform_angle_opengl;
+    GLFWbool        ANGLE_platform_angle_d3d;
+    GLFWbool        ANGLE_platform_angle_vulkan;
+    GLFWbool        ANGLE_platform_angle_metal;
 
     void*           handle;
 

diff --git a/src/init.c b/src/init.c
@@ -53,6 +53,7 @@ static GLFWerrorfun _glfwErrorCallback;
 static _GLFWinitconfig _glfwInitHints =
 {
     GLFW_TRUE,      // hat buttons
+    GLFW_ANGLE_PLATFORM_TYPE_NONE, // ANGLE backend
     {
         GLFW_TRUE,  // macOS menu bar
         GLFW_TRUE   // macOS bundle chdir
@@ -287,6 +288,9 @@ GLFWAPI void glfwInitHint(int hint, int value)
         case GLFW_JOYSTICK_HAT_BUTTONS:
             _glfwInitHints.hatButtons = value;
             return;
+        case GLFW_ANGLE_PLATFORM_TYPE:
+            _glfwInitHints.angleType = value;
+            return;
         case GLFW_COCOA_CHDIR_RESOURCES:
             _glfwInitHints.ns.chdir = value;
             return;

diff --git a/src/internal.h b/src/internal.h
@@ -243,6 +243,7 @@ struct _GLFWerror
 struct _GLFWinitconfig
 {
     GLFWbool      hatButtons;
+    int           angleType;
     struct {
         GLFWbool  menubar;
         GLFWbool  chdir;
@@ -684,7 +685,7 @@ void _glfwPlatformWaitEvents(void);
 void _glfwPlatformWaitEventsTimeout(double timeout);
 void _glfwPlatformPostEmptyEvent(void);
 
-EGLenum _glfwPlatformGetEGLPlatform(void);
+EGLenum _glfwPlatformGetEGLPlatform(EGLint** attribs);
 EGLNativeDisplayType _glfwPlatformGetEGLNativeDisplay(void);
 EGLNativeWindowType _glfwPlatformGetEGLNativeWindow(_GLFWwindow* window);
 

diff --git a/src/win32_window.c b/src/win32_window.c
@@ -2186,8 +2186,44 @@ const char* _glfwPlatformGetClipboardString(void)
     return _glfw.win32.clipboardString;
 }
 
-EGLenum _glfwPlatformGetEGLPlatform(void)
+EGLenum _glfwPlatformGetEGLPlatform(EGLint** attribs)
 {
+    if (_glfw.egl.ANGLE_platform_angle)
+    {
+        int type = 0;
+
+        if (_glfw.egl.ANGLE_platform_angle_opengl)
+        {
+            if (_glfw.hints.init.angleType == GLFW_ANGLE_PLATFORM_TYPE_OPENGL)
+                type = EGL_PLATFORM_ANGLE_TYPE_OPENGL_ANGLE;
+            else if (_glfw.hints.init.angleType == GLFW_ANGLE_PLATFORM_TYPE_OPENGLES)
+                type = EGL_PLATFORM_ANGLE_TYPE_OPENGLES_ANGLE;
+        }
+
+        if (_glfw.egl.ANGLE_platform_angle_d3d)
+        {
+            if (_glfw.hints.init.angleType == GLFW_ANGLE_PLATFORM_TYPE_D3D9)
+                type = EGL_PLATFORM_ANGLE_TYPE_D3D9_ANGLE;
+            else if (_glfw.hints.init.angleType == GLFW_ANGLE_PLATFORM_TYPE_D3D11)
+                type = EGL_PLATFORM_ANGLE_TYPE_D3D11_ANGLE;
+        }
+
+        if (_glfw.egl.ANGLE_platform_angle_vulkan)
+        {
+            if (_glfw.hints.init.angleType == GLFW_ANGLE_PLATFORM_TYPE_VULKAN)
+                type = EGL_PLATFORM_ANGLE_TYPE_VULKAN_ANGLE;
+        }
+
+        if (type)
+        {
+            *attribs = calloc(3, sizeof(EGLint));
+            (*attribs)[0] = EGL_PLATFORM_ANGLE_TYPE_ANGLE;
+            (*attribs)[1] = type;
+            (*attribs)[2] = EGL_NONE;
+            return EGL_PLATFORM_ANGLE_ANGLE;
+        }
+    }
+
     return 0;
 }
 

diff --git a/src/wl_window.c b/src/wl_window.c
@@ -1684,7 +1684,7 @@ const char* _glfwPlatformGetClipboardString(void)
     return _glfw.wl.clipboardString;
 }
 
-EGLenum _glfwPlatformGetEGLPlatform(void)
+EGLenum _glfwPlatformGetEGLPlatform(EGLint** attribs)
 {
     if (_glfw.egl.EXT_platform_base && _glfw.egl.EXT_platform_wayland)
         return EGL_PLATFORM_WAYLAND_EXT;

diff --git a/src/x11_window.c b/src/x11_window.c
@@ -3048,12 +3048,40 @@ const char* _glfwPlatformGetClipboardString(void)
     return getSelectionString(_glfw.x11.CLIPBOARD);
 }
 
-EGLenum _glfwPlatformGetEGLPlatform(void)
+EGLenum _glfwPlatformGetEGLPlatform(EGLint** attribs)
 {
+    if (_glfw.egl.ANGLE_platform_angle)
+    {
+        int type = 0;
+
+        if (_glfw.egl.ANGLE_platform_angle_opengl)
+        {
+            if (_glfw.hints.init.angleType == GLFW_ANGLE_PLATFORM_TYPE_OPENGL)
+                type = EGL_PLATFORM_ANGLE_TYPE_OPENGL_ANGLE;
+        }
+
+        if (_glfw.egl.ANGLE_platform_angle_vulkan)
+        {
+            if (_glfw.hints.init.angleType == GLFW_ANGLE_PLATFORM_TYPE_VULKAN)
+                type = EGL_PLATFORM_ANGLE_TYPE_VULKAN_ANGLE;
+        }
+
+        if (type)
+        {
+            *attribs = calloc(5, sizeof(EGLint));
+            (*attribs)[0] = EGL_PLATFORM_ANGLE_TYPE_ANGLE;
+            (*attribs)[1] = type;
+            (*attribs)[2] = EGL_PLATFORM_ANGLE_NATIVE_PLATFORM_TYPE_ANGLE;
+            (*attribs)[3] = EGL_PLATFORM_X11_EXT;
+            (*attribs)[4] = EGL_NONE;
+            return EGL_PLATFORM_ANGLE_ANGLE;
+        }
+    }
+
     if (_glfw.egl.EXT_platform_base && _glfw.egl.EXT_platform_x11)
         return EGL_PLATFORM_X11_EXT;
-    else
-        return 0;
+
+    return 0;
 }
 
 EGLNativeDisplayType _glfwPlatformGetEGLNativeDisplay(void)