Use ulong for assetid instead of Guid

[paulpach]

Assetid is used to identify which prefab to spawn with a spawn message.

I can't imagine a game having more than 100 or so spawn networked prefabs. So having 128 bits for this is overkill. Even 32 bits would be more than enough.

In addition, Guid has the extra annoyance that unity will not serialize it, so we end up with an awkward conversion from string.

This PR simplifies asset id by using only 64 bits and using ulong instead of Guid for the asset id.

[atlv24]

Looks good! I like it. At some point we can use incremental IDs instead of hashes, and that can cut the size of this down to uint easily, maybe even ushort. But this already is a significant improvement!

[atlv24]

Actually, I think this breaks the weaver. I didnt test it but I think theres some code about Guids that has to be removed. (The references to ReadGuid etc)

[paulpach]

Actually, I think this breaks the weaver. I didnt test it but I think theres some code about Guids that has to be removed. (The references to ReadGuid etc)

Good call. Fixed.

[atlv24]

It would be really nice to have a typedef to keep track of which ulongs are Guids. Maybe it'd be worth it to have using Guid = System.UInt64; at the top of the files that use Guids for now? Or would that just be unnecessary confusion?

[paulpach]

using Guid = System.UInt64; would be extremely confusing.

[miwarnec]

according to a microsoft developer, this doesn't sound like a good idea: https://blogs.msdn.microsoft.com/oldnewthing/20080627-00/?p=21823/

8 bytes don't seem to be worth the worrying that comes with it.

[paulpach]

That was a great read! I was just assuming GUID were random, now I know better.