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

Copyright (c) 2000-2011 Torus Knot Software Ltd

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
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 Software.

THE SOFTWARE IS 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 SOFTWARE OR THE USE OR OTHER DEALINGS IN
THE SOFTWARE.
-----------------------------------------------------------------------------
*/
#ifndef __GLHARWAREBUFFERMANAGER_H__
#define __GLHARWAREBUFFERMANAGER_H__

#include "CmGLPrerequisites.h"
#include "CmHardwareBufferManager.h"

namespace CamelotEngine {

// Default threshold at which glMapBuffer becomes more efficient than glBufferSubData (32k?)
#	define CM_GL_DEFAULT_MAP_BUFFER_THRESHOLD (1024 * 32)


    /** Implementation of HardwareBufferManager for OpenGL. */
    class CM_RSGL_EXPORT GLHardwareBufferManager : public HardwareBufferManager
    {
    public:
        GLHardwareBufferManager();
        ~GLHardwareBufferManager();

        /// 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);

		/** Threshold after which glMapBuffer is used and not glBufferSubData
		*/
		const UINT32 getGLMapBufferThreshold() const;
		void setGLMapBufferThreshold( const UINT32 value );

	protected:
		char* mScratchBufferPool;
		CM_MUTEX(mScratchMutex);
		UINT32 mMapBufferThreshold;

		/**
		 * @copydoc HardwareBufferManager::createVertexBufferImpl
		 */
        VertexBufferPtr createVertexBufferImpl(UINT32 vertexSize, 
            UINT32 numVerts, GpuBufferUsage usage, bool streamOut = false);

		/**
		 * @copydoc HardwareBufferManager::createIndexBufferImpl
		 */
        IndexBufferPtr createIndexBufferImpl(
            IndexBuffer::IndexType itype, UINT32 numIndexes, 
            GpuBufferUsage usage);

		/** @copydoc HardwareBufferManager::createGpuParamBlockImpl */
		GpuParamBlockPtr createGpuParamBlockImpl();

		/**
		 * @copydoc HardwareBufferManager::createGenericBufferImpl
		 *
		 * OpenGL does not support generic buffers so this method will return a dummy instance.
		 */
		GpuBufferPtr createGpuBufferImpl(UINT32 elementCount, UINT32 elementSize, 
			GpuBufferType type, GpuBufferUsage usage, bool randomGpuWrite = false, bool useCounter = false);
    };
}

#endif // __GLHARWAREBUFFERMANAGER_H__
