vertex_data.h

// © Joseph Cameron - All Rights Reserved

#ifndef GDK_GFX_VERTEX_DATA_VIEW_H
#define GDK_GFX_VERTEX_DATA_VIEW_H

#include <optional>
#include <stdexcept>
#include <string>
#include <unordered_map>
#include <vector>

class attribute_data_view final
{
public:
    using attribute_component_type = float; 

    attribute_data_view(attribute_component_type *const pData, 
        const size_t aDataLength, 
        const size_t aComponentCount);

    attribute_component_type *data_begin() const;
    
    size_t data_size() const;
    
    size_t component_count() const;

private:
    attribute_component_type *m_pData; 

    size_t m_DataLength; 

    size_t m_ComponentCount; 
};

class vertex_data final
{
public:
    using index_value_type = unsigned short;

    enum class PrimitiveMode
    {
        Triangles
    };

    using attribute_data_type = 
        std::unordered_map<std::string, attribute_data_view>;
    
    struct interleaved_data_view
    {
        using value_type = attribute_data_view::attribute_component_type;

        value_type *const begin; //TODO: iter type? + const end?

        const std::size_t size;
    };

    PrimitiveMode getPrimitiveMode() const;

    const std::vector<attribute_data_view::attribute_component_type> &getData() const;

    const std::vector<std::pair<std::string, std::size_t>> &attribute_format() const;
    
    size_t attribute_offset(const std::string &aName) const;

    size_t vertex_size() const;

    size_t interleaved_data_size() const;

    //TODO: this returns a constant, need index support
    std::vector<index_value_type> getIndexData() const;

    void operator+=(const vertex_data &&other);
    void push_back(const vertex_data &&other);

    void clear();

    vertex_data(const attribute_data_type &aAttributeData);

    interleaved_data_view view_to_interleaved_data();

    //TODO: transform method?
    // throw if name is not 3 component attribute?
    //void transform(std::string name, sca, rot, tra)

private:
    PrimitiveMode m_PrimitiveMode = PrimitiveMode::Triangles; 

    std::vector<attribute_data_view::attribute_component_type> m_Data;

    std::vector<std::pair<std::string, size_t>> m_Format;

    std::unordered_map<std::string, size_t> m_AttributeOffsets;
};

#endif