NBEngine/engine/NBGraphics/Buffers.hpp

#pragma once
#ifndef _NB_BUFFER
#define _NB_BUFFER

#include "GLLoad.hpp"

#include <memory>
#include <string>

#include <NBCore/Errors.hpp>
#include <NBCore/Logger.hpp>
#include <NBCore/Utils.hpp>

#include "OGLObjects.hpp"

namespace nb {

extern const std::unordered_map<GLenum, std::string> BufferTypes;

class BufferError : public Error<BufferError> {
    protected:
    using Base = Error<BufferError>;
    using Base::Base;

    public:
    enum Codes : unsigned int {
        UNDEFINED,
        DATA_OVERFLOW,
        INVALID_BUFFER,
        HANDLE_OVERWRITE,
    };
    static const std::string type;
    static const ErrorCodeMap ErrorMessages;
};

template <typename BufferType>
class Buffer : public OpenGLObject {
    using Codes = BufferError::Codes;
    
    public:
    using OpenGLObject::OpenGLObject;
    Buffer() = default;
    Buffer(Buffer&& other) {
        *this = std::move(other);
    }
    Buffer& operator=(Buffer&& rhs) {
        auto targ_name = BufferTypes.at(Target);
        if (Target != rhs.Target) {
            THROW(BufferError(
                Codes::INVALID_BUFFER,
                "w/ ("+targ_name+") := ("+BufferTypes.at(rhs.Target)+")"
            ));
        }
        //nb::logger.log(std::to_string(_id) + ":=" + std::to_string(rhs._id));
        if (_id) {
            THROW(BufferError(
                Codes::HANDLE_OVERWRITE,
                "w/ BufferType = " + targ_name
            ));
        }
        _id = rhs._id;
        _usage = rhs._usage;
        _size = rhs._size;

        rhs._id = 0;
        rhs._usage = GL_STATIC_DRAW;
        rhs._size = 0;
        return *this;
    }

    virtual void bind() const override {
        if (_id) {
            glBindBuffer(Target, _id);
        } else {
            WARN(BufferError(
                Codes::INVALID_BUFFER,
                "w/ BufferType " + BufferTypes.at(Target)
            ), 0xFE);
        }
    }
    virtual void unbind() const override { glBindBuffer(Target, 0); }
    virtual GLenum usage() const { return _usage; }
    virtual GLenum usage(GLenum usage_) {
        _usage = usage_;
        data(data(), _usage);
        return _usage;
    }
    virtual size_t size() const { return _size; }
    virtual ByteVector data() const {
        bind();
        ByteVector ret(_size);
        glGetBufferSubData(Target, 0, _size, ret.data());
        return ret;
    }
    virtual void data(
        const void* data_,
        GLsizei size_,
        GLenum usage_=GL_STATIC_DRAW
    ) {
        declare();
        bind();
        glBufferData(Target, size_, data_, usage_);
        _size = size_;
        _usage = usage_;
    }
    virtual void data(const ByteVector& data_, GLenum usage_=GL_STATIC_DRAW) {
        data(data_.data(), data_.size(), usage_);

    }
    virtual void subdata(void* data_, GLsizeiptr size_, GLintptr offset_=0) {
        bind();
        if (offset_+size_ <= _size) {
            THROW(BufferError(BufferError::Codes::DATA_OVERFLOW));
        }
        glBufferSubData(Target, offset_, size_, data_);
    }
    virtual void subdata(ByteVector& data_, GLintptr offset_=0) {
        bind();
        size_t size_ = data_.size();
        if (offset_+size_ <= _size) {
            THROW(BufferError(BufferError::Codes::DATA_OVERFLOW));
        }
        glBufferSubData(Target, offset_, data_.size(), data_.data());
    }
    // virtual void clear() const { glClearBufferData(Target, ) }
    static const GLenum Target;

    protected:
    using OpenGLObject::_id;
    GLenum _usage = GL_STATIC_DRAW;
    size_t _size;
    virtual GLuint declare() override {
        if (!_id) {
            glGenBuffers(1, &_id);
        }
        return _id;
    } 
    virtual void remove() override {
        if (_id) {
            glDeleteBuffers(1, &_id);
            _id = 0;
        }
    }

};

template<typename BufferType>
const GLenum Buffer<BufferType>::Target = BufferType::Target;

template <typename BufferType>
class ImmutableBuffer : public virtual Buffer<BufferType> {
    public:
    using Base = Buffer<BufferType>;
    using Base::Target;
    using Base::bind;

    ImmutableBuffer() = default;
    ImmutableBuffer(size_t size_, GLenum usage_ = GL_STATIC_DRAW, GLbitfield flags_=0x0) : size(size_), Base::usage(usage_) {
        glBufferStorage(Target, size, nullptr, flags_);
    }

    std::weak_ptr<void> map(GLbitfield access_) {
        if (_map && _mapAccess != access_) { unmap(); }
        _mapAccess = access_;
        if (!_map) {
            bind();
            glMapBuffer(Target, _mapAccess);
        }
        return _map;
    }
    void unmap() {
        bind();
        glUnmapBuffer(Target);
        _map.reset();
    }
    
    const size_t size;

protected:
    using Base::_id;
    std::shared_ptr<void> _map = nullptr;
    GLbitfield _mapAccess = 0;

};

template<bool Immutable=false>
class ArrayBuffer : public Buffer<ArrayBuffer<false>> {
    using Base = Buffer<ArrayBuffer<false>>;
    using BufferType = Base;

    public:
    using Base::Base;
    using Base::data;
    ArrayBuffer(const ByteVector&, GLenum usage_=GL_STATIC_DRAW);

    static const GLenum Target = GL_ARRAY_BUFFER;

    protected:
    using Base::_usage;
};

template <>
class ArrayBuffer<true> 
: public virtual ArrayBuffer<false>, public virtual ImmutableBuffer<ArrayBuffer<true>> {
    using Base = ArrayBuffer<false>;
    using BufferType = ImmutableBuffer<ArrayBuffer<true>>;
    using BufferType::BufferType;


    public:
    using Base::Target;

};

template<bool Immutable=false>
class ElementBuffer : public Buffer<ElementBuffer<false>> {
    using Base = Buffer<ElementBuffer<false>>;
    using BufferType = Base;
    
    public:
    using Base::Base;
    static const GLenum Target = GL_ELEMENT_ARRAY_BUFFER;

    protected:

};

template <>
class ElementBuffer<true> 
: public virtual ElementBuffer<false>, public virtual ImmutableBuffer<ElementBuffer<true>> {
    using Base = ElementBuffer<false>;
    using BufferType = ImmutableBuffer<ElementBuffer<true>>;

    public:
    using BufferType::BufferType;
    using Base::Target;

};

} // namespace NB
#endif // _NB_BUFFER