BansheeEngine/BansheeGLRenderSystem/Include/BsGLRenderTexture.h

#pragma once

#include "BsGLPrerequisites.h"
#include "BsGLTexture.h"
#include "BsGLFrameBufferObject.h"
#include "BsModule.h"

// Extra GL constants
#define GL_DEPTH24_STENCIL8_EXT 0x88F0

namespace BansheeEngine 
{  
    /** Base class for GL Render Textures
    */
    class BS_RSGL_EXPORT GLRenderTexture: public RenderTexture
    {
	public:
		virtual ~GLRenderTexture();

		bool requiresTextureFlipping() const { return true; }
		virtual void getCustomAttribute(const String& name, void* pData) const;

	protected:
		friend class GLTextureManager;

		GLRenderTexture();

		/**
		 * @copydoc RenderTexture::initialize_internal().
		 */
		void initialize_internal();

		/**
		 * @copydoc RenderTexture::destroy_internal().
		 */
		void destroy_internal();

		GLFrameBufferObject* mFB;
    };

    /**
     * @brief	Manager/factory for RenderTextures.
     * 			
	 * @note	Must be initialized when RenderSystem is first started.
     */
    class BS_RSGL_EXPORT GLRTTManager : public Module<GLRTTManager>
    {
    public:
        GLRTTManager();
		~GLRTTManager();
        
        /**
         * @brief	Check if a certain format is usable as FBO rendertarget format.
         *
         * @note	Thread safe.
         */
        bool checkFormat(PixelFormat format) { return mProps[format].valid; }
        
        /** Get a FBO without depth/stencil for temporary use, like blitting between textures.
        */
        GLuint getTemporaryFBO() { return mTempFBO; }

        /**
         * @brief	Get the closest supported alternative format. If format is supported, returns format.
         *
         * @note	Thread safe
         */
        virtual PixelFormat getSupportedAlternative(PixelFormat format);
    private:
        /** Frame Buffer Object properties for a certain texture format.
        */
        struct FormatProperties
        {
            bool valid; // This format can be used as RTT (FBO)
            
            /** Allowed modes/properties for this pixel format
            */
            struct Mode
            {
                UINT32 depth;     // Depth format (0=no depth)
                UINT32 stencil;   // Stencil format (0=no stencil)
            };
            
            Vector<Mode> modes;
        };
        /** Properties for all internal formats defined by the engine
        */
        FormatProperties mProps[PF_COUNT];

        /** Temporary FBO identifier
         */
        GLuint mTempFBO;
        
        /** Detect allowed FBO formats */
        void detectFBOFormats();
        GLuint _tryFormat(GLenum depthFormat, GLenum stencilFormat);
        bool _tryPackedFormat(GLenum packedFormat);
    };
}