Initial commit of glContainer

A std::vector like container backed by an OpenGL buffer.

1 files changed, 406 insertions, 0 deletions

diff --git a/lib/glContainer.h b/lib/glContainer.h
new file mode 100644
index 0000000..9e942b4
--- /dev/null
+++ b/lib/glContainer.h
@@ -0,0 +1,406 @@
+#pragma once
+
+#include "glArrays.h"
+#include <stdexcept>
+#include <utility>
+#include <vector>
+
+template<typename I, typename Direction> class basic_glContainer_iterator {
+public:
+	explicit basic_glContainer_iterator(I * i) : i {i} { }
+
+	auto &
+	operator++() noexcept
+	{
+		i = Direction {}(i, 1);
+		return *this;
+	}
+	auto
+	operator++(int) noexcept
+	{
+		return basic_glContainer_iterator<I, Direction> {std::exchange(i, Direction {}(i, 1))};
+	}
+	auto &
+	operator--() noexcept
+	{
+		i = Direction {}(i, -1);
+		return *this;
+	}
+	auto
+	operator--(int) noexcept
+	{
+		return basic_glContainer_iterator<I, Direction> {std::exchange(i, Direction {}(i, -1))};
+	}
+
+	[[nodiscard]] auto
+	operator-(const basic_glContainer_iterator & other) const noexcept
+	{
+		if constexpr (std::is_same_v<Direction, std::plus<>>) {
+			return this->i - other.i;
+		}
+		else {
+			return other.i - this->i;
+		}
+	}
+
+	[[nodiscard]] bool
+	operator==(const basic_glContainer_iterator & other) const noexcept
+	{
+		return this->i == other.i;
+	}
+	[[nodiscard]] bool
+	operator!=(const basic_glContainer_iterator & other) const noexcept
+	{
+		return this->i != other.i;
+	}
+
+	[[nodiscard]] auto
+	operator->() const noexcept
+	{
+		return i;
+	}
+	[[nodiscard]] auto &
+	operator*() const noexcept
+	{
+		return *i;
+	}
+
+private:
+	I * i;
+};
+
+template<typename T> class glContainer {
+public:
+	using value_type = T;
+	using reference_type = T &;
+	using const_reference_type = const T &;
+	using pointer_type = T *;
+	using const_pointer_type = const T *;
+	using size_type = std::size_t;
+	using iterator = basic_glContainer_iterator<value_type, std::plus<>>;
+	using const_iterator = basic_glContainer_iterator<const value_type, std::plus<>>;
+	using reserve_iterator = basic_glContainer_iterator<value_type, std::minus<>>;
+	using const_reserve_iterator = basic_glContainer_iterator<const value_type, std::minus<>>;
+
+	glContainer()
+	{
+		allocBuffer(1);
+	}
+
+	~glContainer()
+	{
+		clear();
+	}
+
+	[[nodiscard]] iterator
+	begin()
+	{
+		map();
+		return iterator {data_};
+	}
+
+	[[nodiscard]] iterator
+	end()
+	{
+		map();
+		return iterator {data_ + size_};
+	}
+
+	[[nodiscard]] const_iterator
+	begin() const
+	{
+		map();
+		return const_iterator {data_};
+	}
+
+	[[nodiscard]] const_iterator
+	end() const
+	{
+		map();
+		return const_iterator {data_ + size_};
+	}
+
+	[[nodiscard]] const_iterator
+	cbegin() const
+	{
+		map();
+		return const_iterator {data_};
+	}
+
+	[[nodiscard]] const_iterator
+	cend() const
+	{
+		map();
+		return const_iterator {data_ + size_};
+	}
+
+	[[nodiscard]] reserve_iterator
+	rbegin()
+	{
+		map();
+		return reserve_iterator {data_ + size_ - 1};
+	}
+
+	[[nodiscard]] reserve_iterator
+	rend()
+	{
+		map();
+		return reserve_iterator {data_ - 1};
+	}
+
+	[[nodiscard]] const_reserve_iterator
+	rbegin() const
+	{
+		map();
+		return const_reserve_iterator {data_ + size_ - 1};
+	}
+
+	[[nodiscard]] const_reserve_iterator
+	rend() const
+	{
+		map();
+		return const_reserve_iterator {data_ - 1};
+	}
+
+	[[nodiscard]] const_reserve_iterator
+	crbegin() const
+	{
+		map();
+		return const_reserve_iterator {data_ + size_ - 1};
+	}
+
+	[[nodiscard]] const_reserve_iterator
+	crend() const
+	{
+		map();
+		return const_reserve_iterator {data_ - 1};
+	}
+
+	[[nodiscard]] size_type
+	size() const
+	{
+		return size_;
+	}
+
+	[[nodiscard]] reference_type
+	at(size_type pos)
+	{
+		if (pos >= size()) {
+			throw std::out_of_range {__FUNCTION__};
+		}
+		map();
+		return data_[pos];
+	}
+
+	[[nodiscard]] const_reference_type
+	at(size_type pos) const
+	{
+		if (pos >= size()) {
+			throw std::out_of_range {__FUNCTION__};
+		}
+		map();
+		return data_[pos];
+	}
+
+	[[nodiscard]] reference_type
+	operator[](size_type pos)
+	{
+		map();
+		return data_[pos];
+	}
+
+	[[nodiscard]] const_reference_type
+	operator[](size_type pos) const
+	{
+		map();
+		return data_[pos];
+	}
+
+	[[nodiscard]] pointer_type
+	data()
+	{
+		map();
+		return data_;
+	}
+
+	[[nodiscard]] const_pointer_type
+	data() const
+	{
+		map();
+		return data_;
+	}
+
+	[[nodiscard]] reference_type
+	front()
+	{
+		map();
+		return *data_;
+	}
+
+	[[nodiscard]] reference_type
+	back()
+	{
+		map();
+		return *(data_ + size_ - 1);
+	}
+
+	[[nodiscard]] const_reference_type
+	front() const
+	{
+		map();
+		return *data_;
+	}
+
+	[[nodiscard]] const_reference_type
+	back() const
+	{
+		map();
+		return *(data_ + size_ - 1);
+	}
+
+	[[nodiscard]] bool
+	empty() const
+	{
+		return !size();
+	}
+
+	[[nodiscard]] size_type
+	capacity() const
+	{
+		return capacity_;
+	}
+
+	void
+	unmap() const
+	{
+		if (data_) {
+			glUnmapNamedBuffer(buffer_);
+			data_ = nullptr;
+		}
+	}
+
+	void
+	reserve(size_type newCapacity)
+	{
+		if (newCapacity <= capacity_) {
+			return;
+		}
+
+		std::vector<T> existing;
+		existing.reserve(size_);
+		map();
+		std::move(begin(), end(), std::back_inserter(existing));
+		allocBuffer(newCapacity);
+		map();
+		std::move(existing.begin(), existing.end(), begin());
+	}
+
+	void
+	resize(size_type newSize)
+	{
+		if (newSize == size_) {
+			return;
+		}
+
+		const auto maintain = std::min(newSize, capacity_);
+		std::vector<T> existing;
+		const auto maintaind = static_cast<typename decltype(existing)::difference_type>(maintain);
+		existing.reserve(maintain);
+		map();
+		std::move(data_, data_ + maintain, std::back_inserter(existing));
+		for (auto uninitialised = data_ + newSize; uninitialised < data_ + size_; ++uninitialised) {
+			uninitialised->~T();
+		}
+		allocBuffer(newSize);
+		map();
+		std::move(existing.begin(), existing.begin() + maintaind, data_);
+		for (auto uninitialised = data_ + size_; uninitialised < data_ + newSize; ++uninitialised) {
+			new (uninitialised) T {};
+		}
+		size_ = newSize;
+	}
+
+	void
+	shrink_to_fit()
+	{
+		if (capacity_ <= size_) {
+			return;
+		}
+
+		std::vector<T> existing;
+		existing.reserve(size_);
+		map();
+		std::move(begin(), end(), std::back_inserter(existing));
+		allocBuffer(size_);
+		map();
+		std::move(existing.begin(), existing.end(), begin());
+	}
+
+	void
+	clear()
+	{
+		std::for_each(begin(), end(), [](auto && v) {
+			v.~T();
+		});
+		size_ = 0;
+	}
+
+	template<typename... P>
+	reference_type
+	emplace_back(P &&... ps)
+	{
+		auto newSize = size_ + 1;
+		reserve(newSize);
+		map();
+		new (data_ + size_) T {std::forward<P>(ps)...};
+		size_ = newSize;
+		return back();
+	}
+
+	reference_type
+	push_back(T p)
+	{
+		auto newSize = size_ + 1;
+		reserve(newSize);
+		map();
+		new (data_ + size_) T {std::move(p)};
+		size_ = newSize;
+		return back();
+	}
+
+protected:
+	void
+	allocBuffer(size_type newCapacity)
+	{
+		if (newCapacity == 0) {
+			return allocBuffer(1);
+		}
+		glBindBuffer(GL_ARRAY_BUFFER, buffer_);
+		glBufferData(GL_ARRAY_BUFFER, static_cast<GLsizeiptr>(sizeof(T) * newCapacity), nullptr, GL_DYNAMIC_DRAW);
+		glBindBuffer(GL_ARRAY_BUFFER, 0);
+		capacity_ = newCapacity;
+		data_ = nullptr;
+	}
+
+	void
+	map() const
+	{
+		if (!data_) {
+			data_ = static_cast<T *>(glMapNamedBuffer(buffer_, GL_READ_WRITE));
+			assert(data_);
+		}
+	}
+
+	glBuffer buffer_;
+	std::size_t capacity_ {};
+	std::size_t size_ {};
+	mutable T * data_ {};
+};
+
+template<typename T, typename D> struct std::iterator_traits<basic_glContainer_iterator<T, D>> {
+	using difference_type = ssize_t;
+	using value_type = T;
+	using pointer = T *;
+	using reference = T &;
+	using iterator_category = std::random_access_iterator_tag;
+};