From b73a3c677171a13bdd7b0044071601647bfbfe67 Mon Sep 17 00:00:00 2001
From: Dan Goodliffe <dan.goodliffe@octal.co.uk>
Date: Tue, 10 Mar 2026 09:40:37 +0000
Subject: Refactor glMappedBufferWriter into a DSA wrapper for std::span

---
 lib/glMappedBufferSpan.h     | 51 +++++++++++++++++++++++++++++
 lib/glMappedBufferWriter.cpp |  4 ---
 lib/glMappedBufferWriter.h   | 78 --------------------------------------------
 3 files changed, 51 insertions(+), 82 deletions(-)
 create mode 100644 lib/glMappedBufferSpan.h
 delete mode 100644 lib/glMappedBufferWriter.cpp
 delete mode 100644 lib/glMappedBufferWriter.h

(limited to 'lib')

diff --git a/lib/glMappedBufferSpan.h b/lib/glMappedBufferSpan.h
new file mode 100644
index 0000000..d30c911
--- /dev/null
+++ b/lib/glMappedBufferSpan.h
@@ -0,0 +1,51 @@
+#pragma once
+
+#include "special_members.h"
+#include <cstddef>
+#include <glad/gl.h>
+#include <span>
+#include <utility>
+
+template<typename T> class glMappedBufferSpan : public std::span<T> {
+public:
+	glMappedBufferSpan(GLuint buffer, size_t count, GLenum access, bool reinit) :
+		std::span<T> {[&]() {
+						  if (reinit) {
+							  glNamedBufferData(
+									  buffer, static_cast<GLsizeiptr>(sizeof(T) * count), nullptr, GL_DYNAMIC_DRAW);
+						  }
+						  return static_cast<T *>(glMapNamedBuffer(buffer, access));
+					  }(),
+				count},
+		buffer {buffer}
+	{
+	}
+
+	~glMappedBufferSpan()
+	{
+		if (buffer) {
+			glUnmapNamedBuffer(buffer);
+		}
+	}
+
+	glMappedBufferSpan(glMappedBufferSpan && other) noexcept :
+		std::span<T> {other}, buffer {std::exchange(other.buffer, 0)}
+	{
+	}
+
+	glMappedBufferSpan &
+	operator=(glMappedBufferSpan && other) noexcept
+	{
+		std::span<T>::span = other;
+		if (buffer) {
+			glUnmapBuffer(buffer);
+		}
+		buffer = std::exchange(other.buffer, 0);
+		return *this;
+	}
+
+	NO_COPY(glMappedBufferSpan);
+
+private:
+	GLuint buffer;
+};
diff --git a/lib/glMappedBufferWriter.cpp b/lib/glMappedBufferWriter.cpp
deleted file mode 100644
index cc3c413..0000000
--- a/lib/glMappedBufferWriter.cpp
+++ /dev/null
@@ -1,4 +0,0 @@
-#include "glMappedBufferWriter.h"
-#include <iterator>
-
-static_assert(std::weakly_incrementable<glMappedBufferWriter<int>>);
diff --git a/lib/glMappedBufferWriter.h b/lib/glMappedBufferWriter.h
deleted file mode 100644
index 05540e4..0000000
--- a/lib/glMappedBufferWriter.h
+++ /dev/null
@@ -1,78 +0,0 @@
-#pragma once
-
-#include "special_members.h"
-#include <cstddef>
-#include <glad/gl.h>
-#include <utility>
-
-template<typename T> class glMappedBufferWriter {
-public:
-	using difference_type = std::ptrdiff_t;
-
-	glMappedBufferWriter(GLenum target, GLuint buffer, size_t count) :
-		target {target}, data {[&]() {
-			glBindBuffer(target, buffer);
-			glBufferData(target, static_cast<GLsizeiptr>(sizeof(T) * count), nullptr, GL_DYNAMIC_DRAW);
-			return static_cast<T *>(glMapBuffer(target, GL_WRITE_ONLY));
-		}()}
-	{
-	}
-
-	~glMappedBufferWriter()
-	{
-		if (target) {
-			glUnmapBuffer(target);
-		}
-	}
-
-	glMappedBufferWriter(glMappedBufferWriter && other) noexcept :
-		target {std::exchange(other.target, 0)}, data {std::exchange(other.data, nullptr)}
-	{
-	}
-
-	glMappedBufferWriter &
-	operator=(glMappedBufferWriter && other) noexcept
-	{
-		if (target) {
-			glUnmapBuffer(target);
-		}
-		target = std::exchange(other.target, 0);
-		data = std::exchange(other.data, nullptr);
-		return *this;
-	}
-
-	NO_COPY(glMappedBufferWriter);
-
-	glMappedBufferWriter &
-	operator++()
-	{
-		data++;
-		return *this;
-	}
-
-	glMappedBufferWriter &
-	operator++(int)
-	{
-		glMappedBufferWriter rtn {data};
-		data++;
-		return rtn;
-	}
-
-	T &
-	operator*()
-	{
-		return *data;
-	}
-
-	T *
-	operator->() const
-	{
-		return data;
-	}
-
-private:
-	explicit glMappedBufferWriter(T * data) : target {0}, data {data} { }
-
-	GLenum target;
-	T * data;
-};
-- 
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