Add GL Stream Buffer from Duckstation

third_party/duckstation/gl/stream_buffer.h

@@ -0,0 +1,53 @@
+// SPDX-FileCopyrightText: 2019-2023 Connor McLaughlin <stenzek@gmail.com>
+// SPDX-License-Identifier: (GPL-3.0 OR CC-BY-NC-ND-4.0)
+
+#pragma once
+
+#include <glad/gl.h>
+// Comment to avoid clang-format reordering the glad header
+
+#include <memory>
+#include <string_view>
+#include <tuple>
+#include <vector>
+
+#include "duckstation_compat.h"
+#include "helpers.hpp"
+
+class OpenGLStreamBuffer {
+  public:
+	virtual ~OpenGLStreamBuffer();
+
+	ALWAYS_INLINE GLuint GetGLBufferId() const { return m_buffer_id; }
+	ALWAYS_INLINE GLenum GetGLTarget() const { return m_target; }
+	ALWAYS_INLINE u32 GetSize() const { return m_size; }
+
+	void Bind();
+	void Unbind();
+
+	void SetDebugName(std::string_view name);
+
+	struct MappingResult {
+		void* pointer;
+		u32 buffer_offset;
+		u32 index_aligned;  // offset / alignment, suitable for base vertex
+		u32 space_aligned;  // remaining space / alignment
+	};
+
+	virtual MappingResult Map(u32 alignment, u32 min_size) = 0;
+
+	/// Returns the position in the buffer *before* the start of used_size.
+	virtual u32 Unmap(u32 used_size) = 0;
+
+	/// Returns the minimum granularity of blocks which sync objects will be created around.
+	virtual u32 GetChunkSize() const = 0;
+
+	static std::unique_ptr<OpenGLStreamBuffer> Create(GLenum target, u32 size);
+
+  protected:
+	OpenGLStreamBuffer(GLenum target, GLuint buffer_id, u32 size);
+
+	GLenum m_target;
+	GLuint m_buffer_id;
+	u32 m_size;
+};