NBEngine/engine/NBGraphics/Buffers.hpp

#pragma once
#ifndef _NB_BUFFER
#define _NB_BUFFER

#include "GLLoad.hpp"

#include <memory>
#include <string>
#include <vector>

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

#include "OGLObjects.hpp"

namespace nb {

static uint8_t GLSLTypeSize(GLenum type) {
    switch(type) {
    case GL_SHORT:
    case GL_UNSIGNED_SHORT:
    case GL_HALF_FLOAT:
        return 2;
        break;
    case GL_INT:
    case GL_UNSIGNED_INT:
    case GL_FLOAT:
        return 4;
        break;
    case GL_DOUBLE:
        return 8;
        break;
    default:
        return 1;
        break;
    }
}

template<typename T>
ByteVector vectorToRaw(const std::vector<T>& vec) {
    unsigned int num_bytes = vec.size() * sizeof(T);
    ByteVector ret(num_bytes);
    memcpy(ret.data(), vec.data(), num_bytes);
    return ret;
}

template<typename T, typename S>
ByteVector concatVectorsToRaw(const std::vector<T>& vec1, const std::vector<S>& vec2) {
    ByteVector vec1_raw = vectorToRaw<T>(vec1);
    ByteVector vec2_raw = vectorToRaw<S>(vec2);
    unsigned int vec1_raw_size = vec1_raw.size();
    unsigned int vec2_raw_size = vec2_raw.size();
    ByteVector ret(vec1_raw_size + vec2_raw_size);
    memcpy(ret.data(), vec1_raw.data(), vec1_raw_size);
    memcpy(ret.data() + vec1_raw_size, vec2_raw.data(), vec2_raw_size);
    return ret;
}

template<typename T>
std::vector<T> rawToVector(const ByteVector& vec) {
    if (vec.size() % sizeof(T) != 0) {
        THROW(std::runtime_error("Data size does not align to std::vector<" + std::string(typeid(T).name()) + ">."));
    }
    unsigned int num_elmts = vec.size() / sizeof(T);
    std::vector<T> ret(num_elmts);
    memcpy(ret.data(), vec.data(), vec.size());

    return ret;
}

class BufferError : public Error<BufferError> {
    using Base = Error<BufferError>;
    
    public:
    using Base::Base;
    
    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) {
        if (_id) { THROW(BufferError(Codes::HANDLE_OVERWRITE)); }
        _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);
        }
        THROW(BufferError(Codes::INVALID_BUFFER));
    }
    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 virtual 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