index_buffer.hpp

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#pragma once
 
#include "gl_functions.hpp"
#include <cstdint>
#include <iostream>
#include <span>
 
namespace staplegl {
 
class index_buffer {
public:
    index_buffer() = default;
 
    index_buffer(std::span<const std::uint32_t> indices) noexcept;
 
    ~index_buffer();
 
    index_buffer(const index_buffer&) = delete;
    auto operator=(const index_buffer&) -> index_buffer& = delete;
 
    index_buffer(index_buffer&&) noexcept;
 
    auto operator=(index_buffer&&) noexcept -> index_buffer&;
 
    void bind() const;
 
    void unbind() const;
 
    [[nodiscard]] constexpr auto count() const -> std::int32_t;
 
    [[nodiscard]] constexpr auto id() const -> std::uint32_t;
 
private:
    std::uint32_t m_id {};
    std::int32_t m_count {};
};
 
inline index_buffer::index_buffer(std::span<const std::uint32_t> indices) noexcept
    : m_count { static_cast<int32_t>(indices.size()) }
{
    glGenBuffers(1, &m_id);
    glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, m_id);
 
    glBufferData(GL_ELEMENT_ARRAY_BUFFER, 
    static_cast<ptrdiff_t>(indices.size_bytes()), 
    indices.data(), 
    GL_STATIC_DRAW);
}
 
inline index_buffer::~index_buffer()
{
    if (m_id != 0) {
        glDeleteBuffers(1, &m_id);
    }
}
 
inline index_buffer::index_buffer(index_buffer&& other) noexcept
    : m_id { other.m_id }
    , m_count { other.m_count }
{
    other.m_id = 0;
}
 
inline auto index_buffer::operator=(index_buffer&& other) noexcept -> index_buffer&
{
    if (this != &other) {
        m_id = other.m_id;
        m_count = other.m_count;
 
        other.m_id = 0;
    }
 
    return *this;
}
 
inline void index_buffer::bind() const
{
    glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, m_id);
}
 
inline void index_buffer::unbind() const
{
    glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, 0);
}
 
constexpr auto index_buffer::count() const -> std::int32_t
{
    return m_count;
}
}