OPENGL: Add a Context class used to describe the active OpenGL context

graphics/opengl/context.h

@@ -0,0 +1,88 @@
+/* ResidualVM - A 3D game interpreter
+ *
+ * ResidualVM is the legal property of its developers, whose names
+ * are too numerous to list here. Please refer to the COPYRIGHT
+ * file distributed with this source distribution.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.	 See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ *
+ */
+
+#ifndef GRAPHICS_OPENGL_CONTEXT_H
+#define GRAPHICS_OPENGL_CONTEXT_H
+
+#include "common/singleton.h"
+
+namespace OpenGL {
+
+enum ContextType {
+	kContextGL,
+	kContextGLES2
+};
+
+/**
+ * Description structure of the OpenGL (ES) context.
+ *
+ * This class is based on LordHoto's OpenGL backend for ScummVM
+ */
+class Context : public Common::Singleton<Context> {
+public:
+	Context();
+
+	/**
+	 * Initialize the context description from currently active context.
+	 *
+	 * The extensions and features are marked as available according
+	 * to the current context capabilities.
+	 */
+	void initialize(ContextType contextType);
+
+	/**
+	 * Reset context.
+	 *
+	 * This marks all extensions as unavailable.
+	 */
+	void reset();
+
+	/** The type of the active context. */
+	ContextType type;
+
+	/** The maximum texture size supported by the context. */
+	int maxTextureSize;
+
+	/** Whether GL_ARB_texture_non_power_of_two is available or not. */
+	bool NPOTSupported;
+
+	/** Whether shader support is available or not. */
+	bool shadersSupported;
+
+	/** Whether FBO support is available or not. */
+	bool framebufferObjectSupported;
+
+	/** Whether packing the depth and stencil buffers is possible or not. */
+	bool packedDepthStencilSupported;
+
+	/** Whether specifying a pitch when uploading to textures is available or not */
+	bool unpackSubImageSupported;
+
+	int getGLSLVersion() const;
+};
+
+} // End of namespace OpenGL
+
+/** Shortcut for accessing the active OpenGL context. */
+#define OpenGLContext OpenGL::Context::instance()
+
+#endif