The bones of what will become a Metal backend.

This isn't anywhere close to usable (not even a blank screen will work), let alone complete. It's about 20% done.

src/modules/graphics/metal/Buffer.mm

@@ -0,0 +1,79 @@
+/**
+* Copyright (c) 2006-2020 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.
+**/
+
+#import "Buffer.h"
+
+namespace love
+{
+namespace graphics
+{
+namespace metal
+{
+
+Buffer::Buffer(id<MTLDevice> device, size_t size, const void *data, BufferType type, vertex::Usage usage, uint32 mapflags)
+	: love::graphics::Buffer(size, type, usage, mapflags)
+	, mappedRange()
+{ @autoreleasepool {
+	MTLResourceOptions opts = MTLResourceStorageModeManaged;
+	buffer = [device newBufferWithLength:size options:opts];
+
+	// TODO: synchronization etc
+	memoryMap = (char *) buffer.contents;
+
+	if (data != nullptr)
+	{
+		memcpy(map(), data, size);
+		unmap();
+	}
+}}
+
+Buffer::~Buffer()
+{ @autoreleasepool {
+	buffer = nil;
+}}
+
+void *Buffer::map()
+{
+	return memoryMap;
+}
+
+void Buffer::unmap()
+{ @autoreleasepool {
+	[buffer didModifyRange:{0, size}];
+}}
+
+void Buffer::setMappedRangeModified(size_t offset, size_t size)
+{
+	mappedRange = NSIntersectionRange(mappedRange, {offset, size});
+}
+
+void Buffer::fill(size_t offset, size_t size, const void *data)
+{
+	// TODO
+}
+
+void Buffer::copyTo(size_t offset, size_t size, love::graphics::Buffer *other, size_t otheroffset)
+{
+	// TODO
+}
+
+} // metal
+} // graphics
+} // love