magnum/src/AbstractFramebuffer.h

#ifndef Magnum_AbstractFramebuffer_h
#define Magnum_AbstractFramebuffer_h
/*
    Copyright © 2010, 2011, 2012 Vladimír Vondruš <mosra@centrum.cz>

    This file is part of Magnum.

    Magnum is free software: you can redistribute it and/or modify
    it under the terms of the GNU Lesser General Public License version 3
    only, as published by the Free Software Foundation.

    Magnum 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 version 3 for more details.
*/

/** @file
 * @brief Class Magnum::AbstractFramebuffer
 */

#include <Containers/EnumSet.h>

#include "Math/Geometry/Rectangle.h"
#include "AbstractImage.h"
#include "Buffer.h"

namespace Magnum {

/**
@brief Base for default and named framebuffers

See DefaultFramebuffer and Framebuffer for more information.

@section AbstractFramebuffer-performance-optimization Performance optimizations

The engine tracks currently bound framebuffer and current viewport to avoid
unnecessary calls to @fn_gl{BindFramebuffer} and @fn_gl{Viewport} when
switching framebuffers.

@todo @extension{ARB,viewport_array}
*/
class MAGNUM_EXPORT AbstractFramebuffer {
    friend class Context;

    AbstractFramebuffer(const AbstractFramebuffer& other) = delete;
    AbstractFramebuffer(AbstractFramebuffer&& other) = delete;
    AbstractFramebuffer& operator=(const AbstractFramebuffer& other) = delete;
    AbstractFramebuffer& operator=(AbstractFramebuffer&& other) = delete;

    public:
        /**
         * @brief Mask for clearing
         *
         * @see ClearMask
         */
        enum class Clear: GLbitfield {
            Color = GL_COLOR_BUFFER_BIT,    /**< Color */
            Depth = GL_DEPTH_BUFFER_BIT,    /**< Depth value */
            Stencil = GL_STENCIL_BUFFER_BIT /**< Stencil value */
        };

        /**
         * @brief Mask for clearing
         *
         * @see clear()
         */
        typedef Corrade::Containers::EnumSet<Clear, GLbitfield,
            GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT|GL_STENCIL_BUFFER_BIT> ClearMask;

        /**
         * @brief Mask for blitting
         *
         * @see BlitMask
         * @requires_gl30 %Extension @extension{EXT,framebuffer_object}
         * @requires_gles30 %Extension @es_extension{ANGLE,framebuffer_blit}
         */
        enum class Blit: GLbitfield {
            ColorBuffer = GL_COLOR_BUFFER_BIT,    /**< Color buffer */
            DepthBuffer = GL_DEPTH_BUFFER_BIT,    /**< Depth buffer */
            StencilBuffer = GL_STENCIL_BUFFER_BIT /**< Stencil buffer */
        };

        /**
         * @brief Mask for blitting
         *
         * @see blit()
         * @requires_gl30 %Extension @extension{EXT,framebuffer_object}
         * @requires_gles30 %Extension @es_extension{ANGLE,framebuffer_blit}
         */
        typedef Corrade::Containers::EnumSet<Blit, GLbitfield,
            GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT|GL_STENCIL_BUFFER_BIT> BlitMask;

        /**
         * @brief Blit filtering
         *
         * @see blit()
         */
        enum class BlitFilter: GLenum {
            NearestNeighbor = GL_NEAREST,   /**< Nearest neighbor filtering */
            LinearInterpolation = GL_LINEAR /**< Linear interpolation filtering */
        };

        /**
         * @brief Target for binding framebuffer
         *
         * @see DefaultFramebuffer::bind(), Framebuffer::bind()
         * @requires_gl30 %Extension @extension{EXT,framebuffer_object}
         */
        enum class Target: GLenum {
            /**
             * For reading only.
             * @requires_gl30 %Extension @extension{EXT,framebuffer_blit}
             * @requires_gles30 %Extension @es_extension{APPLE,framebuffer_multisample}
             *      or @es_extension{ANGLE,framebuffer_blit}
             */
            #ifndef MAGNUM_TARGET_GLES2
            Read = GL_READ_FRAMEBUFFER,
            #else
            Read = GL_READ_FRAMEBUFFER_APPLE,
            #endif

            /**
             * For drawing only.
             * @requires_gl30 %Extension @extension{EXT,framebuffer_blit}
             * @requires_gles30 %Extension @es_extension{APPLE,framebuffer_multisample}
             *      or @es_extension{ANGLE,framebuffer_blit}
             */
            #ifndef MAGNUM_TARGET_GLES2
            Draw = GL_DRAW_FRAMEBUFFER,
            #else
            Draw = GL_DRAW_FRAMEBUFFER_APPLE,
            #endif

            ReadDraw = GL_FRAMEBUFFER       /**< For both reading and drawing. */
        };

        /**
         * @brief Copy block of pixels
         * @param source            Source framebuffer
         * @param destination       Destination framebuffer
         * @param sourceRectangle   Source rectangle
         * @param destinationRectangle Destination rectangle
         * @param mask              Which buffers to perform blit operation on
         * @param filter            Interpolation filter
         *
         * Binds @p source framebuffer to @ref Target "Target::Read" and
         * @p destination framebuffer to @ref Target "Target::Draw" and
         * performs blitting operation. See DefaultFramebuffer::mapForRead(),
         * Framebuffer::mapForRead(), DefaultFramebuffer::mapForDraw() and
         * Framebuffer::mapForDraw() for specifying particular buffers for
         * blitting operation.
         * @see @fn_gl{BlitFramebuffer}
         * @requires_gl30 %Extension @extension{EXT,framebuffer_blit}
         * @requires_gles30 %Extension @es_extension{ANGLE,framebuffer_blit}
         */
        static void blit(AbstractFramebuffer& source, AbstractFramebuffer& destination, const Rectanglei& sourceRectangle, const Rectanglei& destinationRectangle, BlitMask mask, BlitFilter filter);

        /**
         * @brief Copy block of pixels
         * @param source            Source framebuffer
         * @param destination       Destination framebuffer
         * @param rectangle         Source and destination rectangle
         * @param mask              Which buffers to perform blit operation on
         *
         * Convenience alternative to above function when source rectangle is
         * the same as destination rectangle. As the image is copied
         * pixel-by-pixel, no interpolation is needed and thus
         * @ref BlitFilter "BlitFilter::NearestNeighbor" filtering is used by
         * default.
         * @see @fn_gl{BlitFramebuffer}
         * @requires_gl30 %Extension @extension{EXT,framebuffer_blit}
         * @requires_gles30 %Extension @es_extension{ANGLE,framebuffer_blit}
         */
        inline static void blit(AbstractFramebuffer& source, AbstractFramebuffer& destination, const Rectanglei& rectangle, BlitMask mask) {
            blit(source, destination, rectangle, rectangle, mask, BlitFilter::NearestNeighbor);
        }

        explicit AbstractFramebuffer() = default;
        virtual ~AbstractFramebuffer() = 0;

        /**
         * @brief Bind framebuffer for rendering
         *
         * Binds the framebuffer and updates viewport to saved dimensions.
         * @see setViewport(), DefaultFramebuffer::mapForRead(),
         *      Framebuffer::mapForRead(), DefaultFramebuffer::mapForDraw(),
         *      Framebuffer::mapForDraw(), @fn_gl{BindFramebuffer},
         *      @fn_gl{Viewport}
         */
        void bind(Target target);

        /** @brief Viewport rectangle */
        inline Rectanglei viewport() const { return _viewport; }

        /**
         * @brief Set viewport
         *
         * Saves the viewport to be used at later time in bind(). If the
         * framebuffer is currently bound, updates the viewport to given
         * rectangle.
         * @see @fn_gl{Viewport}
         */
        void setViewport(const Rectanglei& rectangle);

        /**
         * @brief Clear specified buffers in framebuffer
         * @param mask              Which buffers to clear
         *
         * @see Renderer::setClearColor(), Renderer::setClearDepth(),
         *      Renderer::setClearStencil(), @fn_gl{BindFramebuffer},
         *      @fn_gl{Clear}
         */
        void clear(ClearMask mask);

        /**
         * @brief Read block of pixels from framebuffer to image
         * @param offset            Offset in the framebuffer
         * @param size              %Image size
         * @param format            Format of pixel data
         * @param type              Data type of pixel data
         * @param image             %Image where to put the data
         *
         * @see @fn_gl{BindFramebuffer}, @fn_gl{ReadPixels}
         * @todo Read size, format & type from image?
         */
        void read(const Vector2i& offset, const Vector2i& size, AbstractImage::Format format, AbstractImage::Type type, Image2D* image);

        #ifndef MAGNUM_TARGET_GLES2
        /**
         * @brief Read block of pixels from framebuffer to buffer image
         * @param offset            Offset in the framebuffer
         * @param size              %Image size
         * @param format            Format of pixel data
         * @param type              Data type of pixel data
         * @param image             %Buffer image where to put the data
         * @param usage             %Buffer usage
         *
         * @see @fn_gl{BindFramebuffer}, @fn_gl{ReadPixels}
         * @requires_gles30 Pixel buffer objects are not available in OpenGL ES 2.0.
         * @todo Read size, format & type from image?
         */
        void read(const Vector2i& offset, const Vector2i& size, AbstractImage::Format format, AbstractImage::Type type, BufferImage2D* image, Buffer::Usage usage);
        #endif

    #ifndef DOXYGEN_GENERATING_OUTPUT
    protected:
        void MAGNUM_LOCAL bindInternal(Target target);
        Target MAGNUM_LOCAL bindInternal();
        void MAGNUM_LOCAL setViewportInternal();

        static MAGNUM_LOCAL Target readTarget;
        static MAGNUM_LOCAL Target drawTarget;

        typedef void(AbstractFramebuffer::*DrawBuffersImplementation)(GLsizei, const GLenum*);
        static MAGNUM_LOCAL DrawBuffersImplementation drawBuffersImplementation;

        typedef void(AbstractFramebuffer::*DrawBufferImplementation)(GLenum);
        static DrawBufferImplementation drawBufferImplementation;

        typedef void(AbstractFramebuffer::*ReadBufferImplementation)(GLenum);
        static ReadBufferImplementation readBufferImplementation;

        GLuint _id;
        Rectanglei _viewport;
    #endif

    private:
        static void MAGNUM_LOCAL initializeContextBasedFunctionality(Context* context);

        void MAGNUM_LOCAL drawBuffersImplementationDefault(GLsizei count, const GLenum* buffers);
        #ifndef MAGNUM_TARGET_GLES
        void MAGNUM_LOCAL drawBuffersImplementationDSA(GLsizei count, const GLenum* buffers);
        #endif

        void MAGNUM_LOCAL drawBufferImplementationDefault(GLenum buffer);
        #ifndef MAGNUM_TARGET_GLES
        void MAGNUM_LOCAL drawBufferImplementationDSA(GLenum buffer);
        #endif

        void MAGNUM_LOCAL readBufferImplementationDefault(GLenum buffer);
        #ifndef MAGNUM_TARGET_GLES
        void MAGNUM_LOCAL readBufferImplementationDSA(GLenum buffer);
        #endif
};

inline AbstractFramebuffer::~AbstractFramebuffer() {}

CORRADE_ENUMSET_OPERATORS(AbstractFramebuffer::ClearMask)
#ifndef MAGNUM_TARGET_GLES
CORRADE_ENUMSET_OPERATORS(AbstractFramebuffer::BlitMask)
#endif

}

#endif