BansheeEngine/BansheeCore/Include/BsIndexBuffer.h

#pragma once

#include "BsCorePrerequisites.h"
#include "BsHardwareBuffer.h"
#include "BsCoreObject.h"

namespace BansheeEngine 
{
	/**
	 * @brief	Type of the indices used, used for determining size.
	 */
	enum IndexType 
	{
		IT_16BIT,
		IT_32BIT
	};

	/**
	 * @brief	Contains information about an index buffer.
	 */
	class BS_CORE_EXPORT IndexBufferProperties
	{
	public:
		/**
		 * @brief	Returns the type of indices stored.
		 */
		IndexType getType() const { return mIndexType; }

		/**
		 * @brief	Returns the number of indices this buffer can hold.
		 */
		UINT32 getNumIndices() const { return mNumIndexes; }

		/**
		 * @brief	Returns the size of a single index in bytes.
		 */
		UINT32 getIndexSize() const { return mIndexSize; }

	protected:
		friend class IndexBuffer;
		friend class IndexBufferCore;

		IndexType mIndexType;
		UINT32 mNumIndexes;
		UINT32 mIndexSize;
	};

	/**
	 * @brief	Core thread specific implementation of an index buffer.
	 *
	 * @see		IndexBuffer
	 */
	class BS_CORE_EXPORT IndexBufferCore : public CoreObjectCore, public HardwareBuffer
	{
	public:
		IndexBufferCore(GpuBufferUsage usage, bool useSystemMemory, const IndexBufferProperties& properties);
		virtual ~IndexBufferCore() { }

		/**
		 * @brief	Returns information about the index buffer.
		 */
		const IndexBufferProperties& getProperties() const { return mProperties; }

	protected:
		IndexBufferProperties mProperties;
	};

	/**
	 * @brief	Hardware buffer that hold indices that reference vertices in a vertex buffer.
	 */
    class BS_CORE_EXPORT IndexBuffer : public CoreObject
    {
	public:
		virtual ~IndexBuffer() { }

		/**
		 * @brief	Returns information about the index buffer.
		 */
		const IndexBufferProperties& getProperties() const { return mProperties; }

		/**
		 * @brief	Retrieves a core implementation of an index buffer
		 *			usable only from the core thread.
		 *
		 * @note	Core thread only.
		 */
		SPtr<IndexBufferCore> getCore() const;

		/**
		 * @copydoc	HardwareBufferManager::createIndexBuffer
		 */
		static IndexBufferPtr create(IndexType itype, UINT32 numIndexes, GpuBufferUsage usage);

	protected:
		IndexBuffer(IndexType idxType, UINT32 numIndexes, GpuBufferUsage usage, bool useSystemMemory);

		IndexBufferProperties mProperties;
		GpuBufferUsage mUsage;
		bool mUseSystemMemory;
    };
}