/*
-----------------------------------------------------------------------------
This source file is part of OGRE
    (Object-oriented Graphics Rendering Engine)
For the latest info, see http://www.ogre3d.org/

Copyright (c) 2000-2006 Torus Knot Software Ltd
Also see acknowledgements in Readme.html

This program is free software; you can redistribute it and/or modify it under
the terms of the GNU Lesser 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 Lesser General Public License for more details.

You should have received a copy of the GNU Lesser General Public License along with
this program; if not, write to the Free Software Foundation, Inc., 59 Temple
Place - Suite 330, Boston, MA 02111-1307, USA, or go to
http://www.gnu.org/copyleft/lesser.txt.

You may alternatively use this source under the terms of a specific version of
the OGRE Unrestricted License provided you have obtained such a license from
Torus Knot Software Ltd.
-----------------------------------------------------------------------------
*/
#ifndef __GLHARWAREBUFFERMANAGER_H__
#define __GLHARWAREBUFFERMANAGER_H__

#include "OgreGLPrerequisites.h"
#include "OgreHardwareBufferManager.h"

namespace Ogre {

// Threshold at which glMapBuffer becomes more efficient than glBufferSubData (32k?)
// non-Win32 machines are having issues with this, looks like buffer corruption
// disable for now until we figure out where the problem lies
#if OGRE_PLATFORM == OGRE_PLATFORM_WIN32
#	define OGRE_GL_MAP_BUFFER_THRESHOLD (1024 * 32)
#else
#	define OGRE_GL_MAP_BUFFER_THRESHOLD 0
#endif

    /** Implementation of HardwareBufferManager for OpenGL. */
    class _OgrePrivate GLHardwareBufferManager : public HardwareBufferManager
    {
	protected:
		char* mScratchBufferPool;
		OGRE_MUTEX(mScratchMutex)

    public:
        GLHardwareBufferManager();
        ~GLHardwareBufferManager();
        /// Creates a vertex buffer
        HardwareVertexBufferSharedPtr createVertexBuffer(size_t vertexSize, 
            size_t numVerts, HardwareBuffer::Usage usage, bool useShadowBuffer = false);
        /// Create a hardware vertex buffer
        HardwareIndexBufferSharedPtr createIndexBuffer(
            HardwareIndexBuffer::IndexType itype, size_t numIndexes, 
            HardwareBuffer::Usage usage, bool useShadowBuffer = false);

        /// Utility function to get the correct GL usage based on HBU's
        static GLenum getGLUsage(unsigned int usage);

        /// Utility function to get the correct GL type based on VET's
        static GLenum getGLType(unsigned int type);

		/** Allocator method to allow us to use a pool of memory as a scratch
			area for hardware buffers. This is because glMapBuffer is incredibly
			inefficient, seemingly no matter what options we give it. So for the
			period of lock/unlock, we will instead allocate a section of a local
			memory pool, and use glBufferSubDataARB / glGetBufferSubDataARB
			instead.
		*/
		void* allocateScratch(uint32 size);

		/// @see allocateScratch
		void deallocateScratch(void* ptr);
    };

}

#endif // __GLHARWAREBUFFERMANAGER_H__
