OPENGL: Allow runtime specification of OpenGL mode.

Formerly, we required that the OpenGL mode was fixed at compile time. Now we
allow the code to work with whatever it is given at runtime.

It is still possible to force a context type on compile time.

8 files changed, 162 insertions, 50 deletions

diff --git a/backends/graphics/opengl/context.cpp b/backends/graphics/opengl/context.cpp
index c4869c2ae6..d1776f851d 100644
--- a/backends/graphics/opengl/context.cpp
+++ b/backends/graphics/opengl/context.cpp
@@ -28,15 +28,23 @@
 namespace OpenGL {
 
 void Context::reset() {
+	ready = false;
+	type = kContextGL;
 	NPOTSupported = false;
 }
 
 Context g_context;
 
-void OpenGLGraphicsManager::initializeGLContext() {
+void OpenGLGraphicsManager::initializeGLContext(ContextType type) {
 	// Initialize default state.
 	g_context.reset();
 
+#if USE_FORCED_GL
+	type = kContextGL;
+#elif USE_FORCED_GLES
+	type = kContextGLES;
+#endif
+
 	// Load all functions.
 	// We use horrible trickery to silence C++ compilers.
 	// See backends/plugins/sdl/sdl-provider.cpp for more information.
@@ -64,6 +72,9 @@ void OpenGLGraphicsManager::initializeGLContext() {
 			g_context.NPOTSupported = true;
 		}
 	}
+
+	g_context.ready = true;
+	g_context.type = type;
 }
 
 } // End of namespace OpenGL
diff --git a/backends/graphics/opengl/opengl-func.h b/backends/graphics/opengl/opengl-func.h
index 75bc0b4e81..0ff39c845a 100644
--- a/backends/graphics/opengl/opengl-func.h
+++ b/backends/graphics/opengl/opengl-func.h
@@ -70,9 +70,10 @@ GL_FUNC_DEF(void, glColor4f, (GLfloat red, GLfloat green, GLfloat blue, GLfloat
 GL_FUNC_DEF(void, glViewport, (GLint x, GLint y, GLsizei width, GLsizei height));
 GL_FUNC_DEF(void, glMatrixMode, (GLenum mode));
 GL_FUNC_DEF(void, glLoadIdentity, ());
-#ifdef USE_GLES
+#if !USE_FORCED_GL
 GL_FUNC_DEF(void, glOrthof, (GLfloat left, GLfloat right, GLfloat bottom, GLfloat top, GLfloat zNear, GLfloat zFar));
-#else
+#endif
+#if !USE_FORCED_GLES
 GL_FUNC_DEF(void, glOrtho, (GLdouble left, GLdouble right, GLdouble bottom, GLdouble top, GLdouble near_val, GLdouble far_val));
 #endif
 GL_FUNC_DEF(void, glShadeModel, (GLenum mode));
diff --git a/backends/graphics/opengl/opengl-graphics.cpp b/backends/graphics/opengl/opengl-graphics.cpp
index 1024ee546e..78ae27d8a6 100644
--- a/backends/graphics/opengl/opengl-graphics.cpp
+++ b/backends/graphics/opengl/opengl-graphics.cpp
@@ -759,10 +759,16 @@ void OpenGLGraphicsManager::setActualScreenSize(uint width, uint height) {
 
 	GL_CALL(glMatrixMode(GL_PROJECTION));
 	GL_CALL(glLoadIdentity());
-#ifdef USE_GLES
+#if   USE_FORCED_GLES
 	GL_CALL(glOrthof(0, _outputScreenWidth, _outputScreenHeight, 0, -1, 1));
-#else
+#elif USE_FORCED_GL
 	GL_CALL(glOrtho(0, _outputScreenWidth, _outputScreenHeight, 0, -1, 1));
+#else
+	if (isGLESContext()) {
+		GL_CALL(glOrthof(0, _outputScreenWidth, _outputScreenHeight, 0, -1, 1));
+	} else {
+		GL_CALL(glOrtho(0, _outputScreenWidth, _outputScreenHeight, 0, -1, 1));
+	}
 #endif
 	GL_CALL(glMatrixMode(GL_MODELVIEW));
 	GL_CALL(glLoadIdentity());
@@ -834,9 +840,9 @@ void OpenGLGraphicsManager::setActualScreenSize(uint width, uint height) {
 	++_screenChangeID;
 }
 
-void OpenGLGraphicsManager::notifyContextCreate(const Graphics::PixelFormat &defaultFormat, const Graphics::PixelFormat &defaultFormatAlpha) {
+void OpenGLGraphicsManager::notifyContextCreate(const Graphics::PixelFormat &defaultFormat, const Graphics::PixelFormat &defaultFormatAlpha, ContextType type) {
 	// Initialize context for use.
-	initializeGLContext();
+	initializeGLContext(type);
 
 	// Disable 3D properties.
 	GL_CALL(glDisable(GL_CULL_FACE));
@@ -1014,7 +1020,11 @@ bool OpenGLGraphicsManager::getGLPixelFormat(const Graphics::PixelFormat &pixelF
 		glFormat = GL_RGBA;
 		glType = GL_UNSIGNED_SHORT_4_4_4_4;
 		return true;
-#ifndef USE_GLES
+#if !USE_FORCED_GLES
+	// The formats below are not supported by every GLES implementation.
+	// Thus, we do not mark them as supported when a GLES context is setup.
+	} else if (isGLESContext()) {
+		return false;
 #ifdef SCUMM_LITTLE_ENDIAN
 	} else if (pixelFormat == Graphics::PixelFormat(4, 8, 8, 8, 8, 24, 16, 8, 0)) { // RGBA8888
 		glIntFormat = GL_RGBA;
@@ -1023,8 +1033,6 @@ bool OpenGLGraphicsManager::getGLPixelFormat(const Graphics::PixelFormat &pixelF
 		return true;
 #endif
 	} else if (pixelFormat == Graphics::PixelFormat(2, 5, 5, 5, 0, 10, 5, 0, 0)) { // RGB555
-		// GL_BGRA does not exist in every GLES implementation so should not be configured if
-		// USE_GLES is set.
 		glIntFormat = GL_RGB;
 		glFormat = GL_BGRA;
 		glType = GL_UNSIGNED_SHORT_1_5_5_5_REV;
@@ -1066,7 +1074,7 @@ bool OpenGLGraphicsManager::getGLPixelFormat(const Graphics::PixelFormat &pixelF
 		glFormat = GL_BGRA;
 		glType = GL_UNSIGNED_SHORT_4_4_4_4;
 		return true;
-#endif
+#endif // !USE_FORCED_GLES
 	} else {
 		return false;
 	}
diff --git a/backends/graphics/opengl/opengl-graphics.h b/backends/graphics/opengl/opengl-graphics.h
index 3d5f74b387..5f0436c0b5 100644
--- a/backends/graphics/opengl/opengl-graphics.h
+++ b/backends/graphics/opengl/opengl-graphics.h
@@ -117,6 +117,16 @@ public:
 
 protected:
 	/**
+	 * Whether an OpenGL (context) is active.
+	 */
+	bool isInitialized() const { return g_context.ready; }
+
+	/**
+	 * Whether an GLES context is active.
+	 */
+	bool isGLESContext() const { return g_context.type == kContextGLES; }
+
+	/**
 	 * Set up the actual screen size available for the OpenGL code to do any
 	 * drawing.
 	 *
@@ -133,8 +143,9 @@ protected:
 	 *                           (this is used for the CLUT8 game screens).
 	 * @param defaultFormatAlpha The new default format with an alpha channel
 	 *                           (this is used for the overlay and cursor).
+	 * @param type               Type of the created context.
 	 */
-	void notifyContextCreate(const Graphics::PixelFormat &defaultFormat, const Graphics::PixelFormat &defaultFormatAlpha);
+	void notifyContextCreate(const Graphics::PixelFormat &defaultFormat, const Graphics::PixelFormat &defaultFormatAlpha, ContextType type);
 
 	/**
 	 * Notify the manager that the OpenGL context is about to be destroyed.
@@ -282,8 +293,10 @@ private:
 
 	/**
 	 * Initialize the active context for use.
+	 *
+	 * @param type Type of the context to initialize.
 	 */
-	void initializeGLContext();
+	void initializeGLContext(ContextType type);
 
 protected:
 	/**
diff --git a/backends/graphics/opengl/opengl-sys.h b/backends/graphics/opengl/opengl-sys.h
index f78b3377b3..550dbb44c5 100644
--- a/backends/graphics/opengl/opengl-sys.h
+++ b/backends/graphics/opengl/opengl-sys.h
@@ -30,6 +30,14 @@
 #include "backends/platform/sdl/sdl-sys.h"
 #endif
 
+// We allow to force GL or GLES modes on compile time.
+// For this the USE_GLES_MODE define is used. The following values represent
+// the given selection choices:
+//  0 - Force OpenGL context
+//  1 - Force OpenGL ES context
+#define USE_FORCED_GL   (defined(USE_GLES_MODE) && USE_GLES_MODE == 0)
+#define USE_FORCED_GLES (defined(USE_GLES_MODE) && USE_GLES_MODE == 1)
+
 // On Tizen we include the toolchain's OpenGL file. This is something we
 // actually want to avoid. However, since Tizen uses eglGetProcAddress which
 // is not required to return valid function pointers to non OpenGL extension
@@ -59,10 +67,21 @@
 
 namespace OpenGL {
 
+enum ContextType {
+	kContextGL,
+	kContextGLES
+};
+
 /**
  * Description structure of the OpenGL (ES) context.
  */
 struct Context {
+	/** Whether the context is properly initalized or not. */
+	bool ready;
+
+	/** The type of the active context. */
+	ContextType type;
+
 	/**
 	 * Reset context.
 	 *
diff --git a/backends/graphics/openglsdl/openglsdl-graphics.cpp b/backends/graphics/openglsdl/openglsdl-graphics.cpp
index 1992925998..a945138578 100644
--- a/backends/graphics/openglsdl/openglsdl-graphics.cpp
+++ b/backends/graphics/openglsdl/openglsdl-graphics.cpp
@@ -210,16 +210,22 @@ Common::List<Graphics::PixelFormat> OpenGLSdlGraphicsManager::getSupportedFormat
 	// RGBA4444
 	formats.push_back(Graphics::PixelFormat(2, 4, 4, 4, 4, 12, 8, 4, 0));
 
-#ifndef USE_GLES
+#if !USE_FORCED_GLES
+#if !USE_FORCED_GL
+	if (isInitialized() && !isGLESContext()) {
+#endif
 #ifdef SCUMM_LITTLE_ENDIAN
-	// RGBA8888
-	formats.push_back(Graphics::PixelFormat(4, 8, 8, 8, 8, 24, 16, 8, 0));
+		// RGBA8888
+		formats.push_back(Graphics::PixelFormat(4, 8, 8, 8, 8, 24, 16, 8, 0));
 #else
-	// ABGR8888
-	formats.push_back(Graphics::PixelFormat(4, 8, 8, 8, 8, 0, 8, 16, 24));
+		// ABGR8888
+		formats.push_back(Graphics::PixelFormat(4, 8, 8, 8, 8, 0, 8, 16, 24));
+#endif
+		// RGB555, this is used by SCUMM HE 16 bit games.
+		formats.push_back(Graphics::PixelFormat(2, 5, 5, 5, 0, 10, 5, 0, 0));
+#if !USE_FORCED_GL
+	}
 #endif
-	// RGB555, this is used by SCUMM HE 16 bit games.
-	formats.push_back(Graphics::PixelFormat(2, 5, 5, 5, 0, 10, 5, 0, 0));
 #endif
 
 	formats.push_back(Graphics::PixelFormat::createFormatCLUT8());
@@ -391,7 +397,7 @@ bool OpenGLSdlGraphicsManager::setupMode(uint width, uint height) {
 		}
 	}
 
-#ifdef USE_GLES
+#if USE_FORCED_GLES
 	// SDL2 will create a GLES2 context by default, so this is needed for GLES1-profile
 	// functions to work.
 	SDL_GL_SetAttribute(SDL_GL_CONTEXT_PROFILE_MASK, SDL_GL_CONTEXT_PROFILE_ES);
@@ -403,7 +409,13 @@ bool OpenGLSdlGraphicsManager::setupMode(uint width, uint height) {
 		return false;
 	}
 
-	notifyContextCreate(rgba8888, rgba8888);
+	notifyContextCreate(rgba8888, rgba8888,
+#if USE_FORCED_GLES
+	                    OpenGL::kContextGLES
+#else
+	                    OpenGL::kContextGL
+#endif
+	                   );
 	int actualWidth, actualHeight;
 	getWindowDimensions(&actualWidth, &actualHeight);
 	setActualScreenSize(actualWidth, actualHeight);
@@ -451,7 +463,7 @@ bool OpenGLSdlGraphicsManager::setupMode(uint width, uint height) {
 	_lastVideoModeLoad = SDL_GetTicks();
 
 	if (_hwScreen) {
-		notifyContextCreate(rgba8888, rgba8888);
+		notifyContextCreate(rgba8888, rgba8888, OpenGL::kContextGL);
 		setActualScreenSize(_hwScreen->w, _hwScreen->h);
 		_eventSource->resetKeyboadEmulation(_hwScreen->w - 1, _hwScreen->h - 1);
 	}
diff --git a/backends/platform/tizen/graphics.cpp b/backends/platform/tizen/graphics.cpp
index 971be460d8..caa18c556f 100644
--- a/backends/platform/tizen/graphics.cpp
+++ b/backends/platform/tizen/graphics.cpp
@@ -59,7 +59,7 @@ result TizenGraphicsManager::Construct() {
 
 	// We default to RGB565 and RGBA5551 which is closest to the actual output
 	// mode we setup.
-	notifyContextCreate(Graphics::PixelFormat(2, 5, 6, 5, 0, 11, 5, 0, 0), Graphics::PixelFormat(2, 5, 5, 5, 1, 11, 6, 1, 0));
+	notifyContextCreate(Graphics::PixelFormat(2, 5, 6, 5, 0, 11, 5, 0, 0), Graphics::PixelFormat(2, 5, 5, 5, 1, 11, 6, 1, 0), OpenGL::kContextGLES);
 
 	// Tell our size.
 	int x, y, width, height;
diff --git a/configure b/configure
index 8d465bc37c..2367466a7c 100755
--- a/configure
+++ b/configure
@@ -133,8 +133,7 @@ _png=auto
 _theoradec=auto
 _faad=auto
 _fluidsynth=auto
-_opengl=auto
-_opengles=no
+_opengl_mode=auto
 _readline=auto
 _freetype2=auto
 _taskbar=auto
@@ -940,6 +939,14 @@ Optional Features:
   --enable-verbose-build   enable regular echoing of commands during build
                            process
   --disable-bink           don't build with Bink video support
+  --opengl-mode=MODE       OpenGL (ES) mode to use for OpenGL output [auto]
+                           available modes: auto for autodetection
+                                            none for disabling any OpenGL usage
+                                            any for runtime detection
+                                            gl for forcing OpenGL
+                                            gles for forcing OpenGL ES
+                           WARNING: only specify this manually if you know what
+                           you are doing!
 
 Optional Libraries:
   --with-alsa-prefix=DIR   Prefix where alsa is installed (optional)
@@ -964,9 +971,6 @@ Optional Libraries:
   --with-mpeg2-prefix=DIR  Prefix where libmpeg2 is installed (optional)
   --enable-mpeg2           enable mpeg2 codec for cutscenes [autodetect]
 
-  --disable-opengl         disable OpenGL (ES) support [autodetect]
-  --enable-opengles        enable forced OpenGL ES mode [disabled]
-
   --with-jpeg-prefix=DIR   Prefix where libjpeg is installed (optional)
   --disable-jpeg           disable JPEG decoder [autodetect]
 
@@ -1071,12 +1075,11 @@ for ac_option in $@; do
 	--disable-updates)        _updates=no     ;;
 	--enable-libunity)        _libunity=yes   ;;
 	--disable-libunity)       _libunity=no    ;;
-	--enable-opengl)          _opengl=yes     ;;
-	--disable-opengl)         _opengl=no      ;;
-	--enable-opengles)        _opengles=yes   ;;
-	--disable-opengles)       _opengles=no    ;;
 	--enable-bink)            _bink=yes       ;;
 	--disable-bink)           _bink=no        ;;
+	--opengl-mode=*)
+		_opengl_mode=`echo $ac_option | cut -d '=' -f 2`
+		;;
 	--enable-verbose-build)   _verbose_build=yes ;;
 	--enable-plugins)         _dynamic_modules=yes ;;
 	--default-dynamic)        _plugins_default=dynamic ;;
@@ -2658,8 +2661,7 @@ if test -n "$_host"; then
 			_sdlconfig=sdl2-config
 			# OpenGL(ES) support is mature enough as to be the best option on
 			# the Raspberry Pi, so it's enabled by default.
-			_opengl=yes
-			_opengles=yes
+			_opengl_mode=gles
 			;;
 		dreamcast)
 			append_var DEFINES "-DDISABLE_DEFAULT_SAVEFILEMANAGER"
@@ -2988,8 +2990,7 @@ if test -n "$_host"; then
 			_timidity=no
 			_vkeybd=yes
 			# Tizen relies on the OpenGL ES output thus we always enable it.
-			_opengl=yes
-			_opengles=yes
+			_opengl_mode=gles
 			;;
 		webos)
 			_backend="webos"
@@ -4150,35 +4151,82 @@ echocheck "OpenGL"
 
 case $_backend in
 	openpandora)
-		# Only enable OpenGL ES on the OpanPandora if --enable-opengl is passed in explicitly.
-		if test "$_opengl" = yes ; then
-			_opengl=yes
-			_opengles=yes
+		# Only enable OpenGL ES on the OpanPandora if --opengl-mode=gles is passed in explicitly.
+		if test "$_opengl_mode" = "gles" ; then
 			append_var LIBS "-lGLES_CM -lEGL -lX11"
+		else
+			_opengl_mode=none
 		fi
 		;;
 esac
 
-if test "$_opengl" = auto ; then
+if test "$_opengl_mode" = auto ; then
 	case $_backend in
 		sdl)
-			_opengl=yes
+			case $_sdlversion in
+				1.2.*)
+					# Stock SDL 1.2 only supports OpenGL contexts.
+					_opengl_mode=gl
+					;;
+
+				2.0.*)
+					# SDL2 supports both OpenGL + OpenGL ES contexts.
+					# However, Mac OS X only allows OpenGL context creation at
+					# this time, thus we limit us to OpenGL on that platform.
+					case $_host_os in
+						darwin*)
+							_opengl_mode=gl
+							;;
+
+						*)
+							_opengl_mode=any
+							;;
+					esac
+					;;
+			esac
+			;;
+
+		tizen)
+			# Tizen always runs in GLES mode
+			_opengl_mode=gles
 			;;
 
 		*)
-			_opengl=no
+			_opengl_mode=none
 			;;
 	esac
 fi
 
-if test "$_opengles" = "yes" ; then
-	echo "yes (OpenGL ES)"
-else
-	echo "$_opengl"
-fi
+_opengl=yes
+case $_opengl_mode in
+	auto)
+		# This case should never occur but better safe than sorry.
+		echo "no"
+		_opengl=no
+		;;
+
+	none)
+		echo "no"
+		_opengl=no
+		;;
+
+	any)
+		echo "yes (runtime detection)"
+		add_line_to_config_h "#undef USE_GLES_MODE"
+		;;
+
+	gl)
+		echo "yes (OpenGL)"
+		add_line_to_config_h "#define USE_GLES_MODE 0"
+		;;
+
+	gles)
+		echo "yes (OpenGL ES)"
+		add_line_to_config_h "#define USE_GLES_MODE 1"
+		;;
+esac
 
 define_in_config_if_yes "$_opengl" "USE_OPENGL"
-define_in_config_if_yes "$_opengles" "USE_GLES"
 
 #
 # Check for nasm