NBEngine/engine/NBGraphics/FrameBuffers.hpp

#pragma once
#ifndef _NB_FRAMEBUFFER
#define _NB_FRAMEBUFFER

#include "GLLoad.hpp"

#include <NBCore/Errors.hpp>

#include "Image.hpp"
#include "OGLObjects.hpp"
#include "Textures.hpp"

namespace nb {

class FrameBufferError : public Error<FrameBufferError> {
    protected:
    using Base = Error<FrameBufferError>;
    
    public:
    using Base::Base;
    enum Codes : unsigned int {
        UNDEFINED, INVALID_VALUE
    };
    static const std::string type;
    static const ErrorCodeMap ErrorMessages;
};

class RenderBuffer : public RenderTarget {
    protected:
    GLuint declare() override {
        if (!_id) {
            glRenderbufferStorage(
                GL_RENDERBUFFER,
                format,
                width,
                height
            );
        }
        return _id;
    }
    void remove() override {
        if (_id) {
            unbind();
            glDeleteRenderbuffers(1, &_id);
            _id = 0;
        }
    }

    public:
    const unsigned int width;
    const unsigned int height;
    const GLenum format;
    template<typename PixelType>
    RenderBuffer(unsigned int width_, unsigned int height_) :
        width(width_),
        height(height_),
        format(OGLPixelFormat<PixelType>::glFormat),
        RenderTarget(GL_RENDERBUFFER) 
    { declare(); }
    RenderBuffer(RenderBuffer&& rhs) :
        width(rhs.width),
        height(rhs.height),
        format(rhs.format),
        RenderTarget(std::move(rhs))
    {}
    RenderBuffer& operator=(RenderBuffer&&) = delete;
    void bind() const override {
        if (_id) {
            glBindRenderbuffer(GL_RENDERBUFFER, _id);
        } else {
            THROW(OGLError(
                OGLError::Codes::INVALID_OBJECT,
                "w/ RenderBuffer"
            ));
        }
    }
    void unbind() const override {
        glBindRenderbuffer(GL_RENDERBUFFER, 0);
    }

};

class FrameBufferBase : public OpenGLObject {
    private:
    static bool texTypeIs2D(GLenum texType) {
        switch(texType) {
            case GL_TEXTURE_2D:
            default:
                return true;
                break;
        }
    }
    
    protected:
    using AttachmentMap = std::unordered_map<GLenum, std::shared_ptr<RenderTarget>>;
    AttachmentMap _attachments;
    FrameBufferBase(GLenum target);
    GLuint declare() override;
    void remove() override;
    std::shared_ptr<RenderTarget> detach(GLenum);
    void attach(
        GLenum attachment,
        std::shared_ptr<Texture> texture,
        unsigned int level=0
    );
    void attach(
        GLenum attachment,
        std::shared_ptr<Texture> texture,
        unsigned int level,
        unsigned int layer
    );
    void attach(
        GLenum attachment,
        std::shared_ptr<RenderBuffer> renderBuffer
    ) {
        declare();
        if (attachment == GL_NONE) {
            THROW(FrameBufferError(FrameBufferError::INVALID_VALUE,
                "Cannot attach RenderBuffer to `GL_NONE`"
            ));
        }
        glFramebufferRenderbuffer(
            Target,
            attachment,
            GL_RENDERBUFFER,
            renderBuffer->id()
        );
        _attachments[attachment] = renderBuffer;
    }

    public:
    const GLenum Target;
    void bind() const override;
    void unbind() const override;
    GLenum status() const;
    AttachmentMap getAllBuffers() const;
    std::shared_ptr<RenderTarget> getBuffer(GLenum) const;
};

class ReadFrameBuffer;
class WriteFrameBuffer;

class ReadFrameBuffer : public virtual FrameBufferBase {
    friend WriteFrameBuffer;
    protected:
    using FrameBufferBase::_attachments;
    GLenum _location;

    public:
    using FrameBufferBase::attach;
    ReadFrameBuffer();
    ReadFrameBuffer& operator=(WriteFrameBuffer&&);
    ReadFrameBuffer& operator=(ReadFrameBuffer&&);
    std::shared_ptr<RenderTarget> getReadBuffer() const;
    GLenum getReadLocation() const;
    std::shared_ptr<RenderTarget> setReadBuffer(GLenum attachment);
    template<typename T, typename... Args>
    std::shared_ptr<RenderTarget> setReadBuffer(
        GLenum attachment,
        std::shared_ptr<T> target,
        Args... args
    ) {
        declare();
        FrameBufferBase::attach(attachment, target, args...);
        setReadBuffer(attachment);
        return getReadBuffer();
    }
};

class WriteFrameBuffer : public virtual FrameBufferBase {
    friend ReadFrameBuffer;
    protected:
    using DrawTexVec = std::vector<std::shared_ptr<Texture>>;
    using FrameBufferBase::_attachments;
    std::vector<GLenum> _locations;

    public:
    WriteFrameBuffer();
    WriteFrameBuffer& operator=(ReadFrameBuffer&&);
    WriteFrameBuffer& operator=(WriteFrameBuffer&&);
    template<typename... T>
    void attach(
        GLenum attachment,
        std::shared_ptr<Texture> texture,
        T... args
    ) { FrameBufferBase::attach(attachment, texture, args...); }
    DrawTexVec getWriteBuffers() const;
    std::vector<GLenum> getWriteLocations() const;
    DrawTexVec setWriteBuffers(const std::vector<GLenum>& attachments);
    std::shared_ptr<Texture> setWriteBuffer(GLenum attachment);
    template<typename... T>
    std::shared_ptr<Texture> setWriteBuffer(
        GLenum attachment,
        std::shared_ptr<Texture> texture,
        T... args
    ) {
        attach(attachment, texture, args...);
        setWriteBuffer(attachment);
        return std::static_pointer_cast<Texture>(_attachments.at(attachment));
    }

    RGBA<float> clearColorValue() const;
    RGBA<float> clearColorValue(const RGBA<float>&);
    RGBA<float> clearColorValue(float r, float g, float b, float a);
    double clearDepthValue() const;
    double clearDepthValue(double);
    GLint clearStencilValue() const;
    GLint clearStencilValue(GLint);
    void clear(GLbitfield mask=(
        GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT | GL_STENCIL_BUFFER_BIT
    )) const;
    void clearColor() const;
    void clearDepth() const;
    void clearDepth(float) const;
    void clearStencil() const;
    void clearStencil(GLint) const;
    void clearDepthStencil() const;
    void clearDepthStencil(float, GLint) const;
};

class FrameBuffer : public ReadFrameBuffer, public WriteFrameBuffer {
    protected:
    using FrameBufferBase::_attachments;
    using ReadFrameBuffer::_location;
    using WriteFrameBuffer::_locations;

    public:
    FrameBuffer();
    FrameBuffer& operator=(FrameBuffer&&);
    FrameBuffer& operator=(ReadFrameBuffer&&);
    FrameBuffer& operator=(WriteFrameBuffer&&);
};

} // namespace nb

#endif // _NB_FRAMEBUFFER