Enable (when available) and improve performance of persistently mapped buffer path for the vertex/index buffers used with automatic batching.

--HG--
branch : minor

src/modules/graphics/opengl/FenceSync.h

@@ -0,0 +1,96 @@
+/**
+ * Copyright (c) 2006-2017 LOVE Development Team
+ *
+ * This software is provided 'as-is', without any express or implied
+ * warranty.  In no event will the authors be held liable for any damages
+ * arising from the use of this software.
+ *
+ * Permission is granted to anyone to use this software for any purpose,
+ * including commercial applications, and to alter it and redistribute it
+ * freely, subject to the following restrictions:
+ *
+ * 1. The origin of this software must not be misrepresented; you must not
+ *    claim that you wrote the original software. If you use this software
+ *    in a product, an acknowledgment in the product documentation would be
+ *    appreciated but is not required.
+ * 2. Altered source versions must be plainly marked as such, and must not be
+ *    misrepresented as being the original software.
+ * 3. This notice may not be removed or altered from any source distribution.
+ **/
+
+// LOVE
+#include "OpenGL.h"
+
+// C
+#include <stddef.h>
+#include <vector>
+
+#pragma once
+
+namespace love
+{
+namespace graphics
+{
+namespace opengl
+{
+
+class FenceSync
+{
+public:
+
+	~FenceSync();
+
+	bool fence();
+	bool cpuWait();
+	void cleanup();
+
+private:
+
+	GLsync sync;
+
+}; // FenceSync
+
+class BufferSync
+{
+public:
+
+	~BufferSync();
+
+	void lock(size_t start, size_t length);
+	void wait(size_t start, size_t length);
+	void cleanup();
+
+private:
+
+	struct Range
+	{
+		size_t offset;
+		size_t length;
+
+		bool overlaps(const Range &other) const
+		{
+			return offset < (other.offset + other.length)
+				&& other.offset < (offset + length);
+		}
+	};
+
+	struct Lock
+	{
+		Range range;
+		GLsync sync;
+
+		Lock(const Range &range, GLsync sync)
+			: range(range)
+			, sync(sync)
+		{}
+	};
+
+	void syncWait(GLsync sync);
+
+	std::vector<Lock> locks;
+
+}; // BufferSync
+
+} // opengl
+} // graphics
+} // love