OpenGL: encapsulate VBOs into a class

internal only for now but this will be handy

irr/src/OpenGL/VBO.h

@@ -0,0 +1,57 @@
+// Copyright (C) 2024 sfan5
+// This file is part of the "Irrlicht Engine".
+// For conditions of distribution and use, see copyright notice in irrlicht.h
+
+#pragma once
+
+#include "Common.h"
+#include <cstddef>
+
+namespace irr
+{
+namespace video
+{
+
+class OpenGLVBO
+{
+public:
+	/// @note does not create on GL side
+	OpenGLVBO() = default;
+	/// @note does not free on GL side
+	~OpenGLVBO() = default;
+
+	/// @return "name" (ID) of this buffer in GL
+	GLuint getName() const { return m_name; }
+	/// @return does this refer to an existing GL buffer?
+	bool exists() const { return m_name != 0; }
+
+	/// @return size of this buffer in bytes
+	size_t getSize() const { return m_size; }
+
+	/**
+	 * Upload buffer data to GL.
+	 *
+	 * Changing the size of the buffer is only possible when `offset == 0`.
+	 * @param data data pointer
+	 * @param size number of bytes
+	 * @param offset offset to upload at
+	 * @param usage usage pattern passed to GL (only if buffer is new)
+	 * @param mustShrink force re-create of buffer if it became smaller
+	 * @note modifies GL_ARRAY_BUFFER binding
+	 */
+	void upload(const void *data, size_t size, size_t offset,
+		GLenum usage, bool mustShrink = false);
+
+	/**
+	 * Free buffer in GL.
+	 * @note modifies GL_ARRAY_BUFFER binding
+	 */
+	void destroy();
+
+private:
+	GLuint m_name = 0;
+	size_t m_size = 0;
+};
+
+}
+}