FramebufferObject.h

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/*
 * Copyright (c) Meta Platforms, Inc. and affiliates.
 *
 * This source code is licensed under the MIT license found in the
 * LICENSE file in the root directory of this source tree.
 */
 
#ifndef META_OCEAN_PLATFORM_GL_FRAMEBUFFER_OBJECT_H
#define META_OCEAN_PLATFORM_GL_FRAMEBUFFER_OBJECT_H
 
#include "ocean/platform/gl/GL.h"
#include "ocean/platform/gl/ContextAssociated.h"
#include "ocean/platform/gl/Texture.h"
 
namespace Ocean
{
 
namespace Platform
{
 
namespace GL
{
 
/**
 * This class implements a frame buffer objects that may be used for rendering to texture.
 * The current implementation covers 2D textures as render targets only and does not provide a depth buffer.
 * @ingroup platformgl
 */
class OCEAN_PLATFORM_GL_EXPORT FramebufferObject : public ContextAssociated
{
    friend class ScopedRenderToTexture;
 
    public:
 
        /**
         * Scoped object simplifying the rendering to a texture.
         */
        class OCEAN_PLATFORM_GL_EXPORT ScopedRenderToTexture
        {
            public:
 
                /**
                 * Creates a new scoped render to texture object.
                 * @param framebufferObject Frame buffer object instance
                 * @param texture The texture into which is rendered
                 */
                inline ScopedRenderToTexture(FramebufferObject& framebufferObject, Texture& texture);
 
                /**
                 * Destroys the scoped render to texture object.
                 */
                inline ~ScopedRenderToTexture();
 
                /**
                 * Explicitly releases the scoped object and unbinds the associated render target (already before the scope ends).
                 */
                inline void release();
 
            protected:
 
                /**
                 * Disabled copy constructor.
                 * @param object The object that would be copied
                 */
                ScopedRenderToTexture(const ScopedRenderToTexture& object) = delete;
 
                /**
                 * The disabled assign operator.
                 * @param object The object that would be assigned
                 */
                ScopedRenderToTexture& operator=(const ScopedRenderToTexture& object) = delete;
 
            protected:
 
                /// Framebuffer object for rendering to texture
                FramebufferObject* scopedFramebufferObject;
        };
 
    public:
 
        /**
         * Creates a new frame buffer object.
         */
        FramebufferObject();
 
        /**
         * Destroys the frame buffer object
         */
        virtual ~FramebufferObject();
 
        /**
         * Releases the frame buffer object.
         */
        void release();
 
    protected:
 
        /**
         * Binds the specified texture as render target.
         * @param texture The texture which will be used as render target
         */
        void bindRenderTarget(Texture& texture);
 
        /**
         * Unbinds the render target from a frame buffer.
         */
        void unbindRenderTarget();
 
    protected:
 
        /// The id of the framebuffer object.
        GLuint framebufferObjectId;
 
        /// The viewport coordinates set before changing the render target.
        GLint framebufferOldViewportCoordinates[4];
 
        /// Indicates if the frame buffer object is currently used for rendering into a texture.
        bool framebufferIsBound;
};
 
inline FramebufferObject::ScopedRenderToTexture::ScopedRenderToTexture(FramebufferObject& framebufferObject, Texture& texture) :
    scopedFramebufferObject(&framebufferObject)
{
    scopedFramebufferObject->bindRenderTarget(texture);
}
 
inline FramebufferObject::ScopedRenderToTexture::~ScopedRenderToTexture()
{
    release();
}
 
inline void FramebufferObject::ScopedRenderToTexture::release()
{
    if (scopedFramebufferObject)
    {
        scopedFramebufferObject->unbindRenderTarget();
        scopedFramebufferObject = nullptr;
    }
}
 
}
 
}
 
}
 
#endif // FACEBOOK_PLATOFRM_GL_FRAMEBUFFER_OBJECT_H