BansheeEngine/RenderBeast/Include/BsRenderTexturePool.h

#pragma once

#include "BsRenderBeastPrerequisites.h"
#include "BsPixelUtil.h"

namespace BansheeEngine
{
	class RenderTexturePool;

	/**
	 * @brief	Contains data about a single render texture in the texture pool.
	 */
	struct PooledRenderTexture
	{
		PooledRenderTexture(RenderTexturePool* pool);
		~PooledRenderTexture();

		SPtr<RenderTextureCore> texture;

	private:
		friend class RenderTexturePool;

		RenderTexturePool* mPool;
		bool mIsFree;
	};

	/**
	 * @brief	Contains a pool of render textures meant to accommodate reuse of
	 *			render textures of the same size and format.
	 */
	class RenderTexturePool
	{
	public:
		~RenderTexturePool();

		/**
		 * @brief	Attempts to find the unused render texture with the specified parameters in the pool, 
		 *			or creates a new texture otherwise. When done with the texture make sure to call ::free.
		 *
		 * @param	format				Pixel format used by the texture color surface.
		 * @param	width				Width of the render texture, in pixels.
		 * @param	height				Height of the render texture, in pixels.
		 * @param	hwGamma				Should the written pixels be gamma corrected.
		 * @param	samples				If higher than 1, texture containing multiple samples per pixel is created.
		 */
		SPtr<PooledRenderTexture> get(PixelFormat format, UINT32 width, UINT32 height, bool hwGamma = false, UINT32 samples = 0);

		/**
		 * @brief	Releases a texture previously allocated with ::get. The texture is returned to the pool so that it may be reused later.
		 *			
		 * @note	The texture will be removed from the pool if the last reference to it is deleted. Normally you would call ::release but
		 *			keep a reference if you plan on using it later on.
		 */
		void release(const SPtr<PooledRenderTexture>& texture);

	private:
		friend struct PooledRenderTexture;

		/**
		 * @brief	Registers a newly created render texture in the pool.
		 */
		void _registerTexture(const SPtr<PooledRenderTexture>& texture);

		/**
		 * @brief	Unregisters a created render texture in the pool.
		 */
		void _unregisterTexture(PooledRenderTexture* texture);

		/**
		 * @brief	Checks does the provided texture match the parameters.
		 * 
		 * @param	texture		Texture to match against the parameters.
		 * @param	format		Pixel format used by the texture color surface.
		 * @param	width		Width of the render texture, in pixels.
		 * @param	height		Height of the render texture, in pixels.
		 * @param	hwGamma		Should the written pixels be gamma corrected.
		 * @param	samples		If higher than 1, texture containing multiple samples per pixel is created.
		 */
		bool matches(const SPtr<TextureCore>& texture, PixelFormat format, UINT32 width, UINT32 height, bool hwGamma, UINT32 samples);

		Map<PooledRenderTexture*, std::weak_ptr<PooledRenderTexture>> mTextures;
	};
}