Is Physics.Raycast deterministic?

The simple answer to your question is no.

It now transpires you're already making the "most sophisticated" type of client-server game and you're already highly familiar with doing this.

It's confusing why you'd need to get "deter$$anonymous$$istic" (I guess you mean the same floats) results in the client in that schema because you don't - say - "check the work" in that approach (or it defeats the whole purpose of limited independent thinking on clients). But in any event that's irrelevant, the answer to your question is simply "No" -- enjoy!

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For any beginners reading....

It's not a noobish question, it's a great question.

However ... I have very bad news. I expect you are going about the game totally incorrectly.

$$anonymous$$ultiplayer games are done like this:

one iPad is the "game boss". the other iPads are the "game clients"

EVERYTHING is actually done on the "game boss". All physics, movement, everything.

The rest -- are simply puppets. They do nothing. They just display everything, as told to by the game boss.

What you appear to be trying to do will never, ever work I'm afraid.

I suggest, step back and learn / readup on basic $$anonymous$$P techniques .. you'll be a real video game engineer ASAP! :)

Please note that this question comes up from time to time

http://answers.unity3d.com/questions/412765/multiplayer-multi-agent-and-bullet-question.html

Please up vote my helpful answers there as I need moar points :) Cheers

{Further note -- in some types of games, notably racing vehicle games .. the situation is incredibly complicated. The puppets make predictions about let's say "inter-report" motion and events, and they do their best to align themselves with what the gameBoss is saying, including ridiculously complicated decisions about what to do if it makes the "wrong guess" or whatever. FWIW you can find some advanced discussion on here about such issues. For example, notice the very generous answer here by Whydoidoit .. http://answers.unity3d.com/questions/329457/few-questions-regarding-multiplayer.html Please upvote his valuable answer there as he too needs moar points :) }

{Note .. I use the term "game boss". you could call it a "server" but this is confusing because it makes you think of the "other type" of servers, ie, the player matching server, or if you are doing a $$anonymous$$$$anonymous$$PG the remote server that runs the actual game play. So I just say "game boss" to describe the lead iPad .. you know when it says "host a game or join a game!" essentially. There are many long discussions on here about nothing other than this nomenclature.}

Sorry for the generally bad news !

"The client server architecture works as a general case for most games."

Well, I guess that's true yeah! :)

"However, because its an RTS, I cannot have one client act as a server and send all of the unit data to each client."

So the number is about 1000 ? Shouldn't be an issue. You're talking in a very advanced manner, so you're clearly already experienced on $$anonymous$$ms doing $$anonymous$$P games of all description .. so that won't be an issue in Unity assu$$anonymous$$g you have good update strategies.

"a pseudo client server architecture..." well yes, that's what I alluded to in my first bracket "Further note ..."

"Finally, if I had a server .. etc" well not really, many games you play every day use -- locally, on the iPads or Pcs -the type of architecture we;re describing. Other games (Doom or whatever) have the thinking on an internet server.

Since its an RTS, sending ~1000 unit states across the network to every client every "network update" is unfeasible if I want them to run anywhere near 30fps. $$anonymous$$any current RTS games use a lock step architecture developed by the developers on AOE, so I was thinking about replicating that technique. However, I can do other architectures and as long as I build it correctly it should run.

The client-server architecture has syncing issues that can be dealt with if a few units are synced every frame. That will guarantee that the units are consistent across machines. However, it still goes back to my main issue of whether or not the raycast is deter$$anonymous$$istic. Floating point calculations are not guaranteed to be consistent between machines or even between instances. Therefore, I need to take that into consideration when I build the architecture that is supposed to handle de-synchronizations between clients caused by floating point errors.

Well the good news is, as it says at the top of my answer, "The simple answer to your question is no."

once again -- the answer is no

Just as a curiosity I don't really see how it's relevant because there's no conceivable predictive $$anonymous$$P strategy where you are "relying on" two outcomes to be the same. It's possible that, just here in Unity or something, you are looking at it in a let's say Unity-unusual way that essentially makes my response "yeah it's a float so they won't be the same but it sounds odd you are looking fro them to be the same."

"1000 unit states .. is unfeasible" you may be surprised how much data you can pump. it goes without saying you would be using various strategies (which obviously you would be familiar with based on your expert knowledge) and you often have to send remarkably little actual bits, it's surprising how it works out

"Floating point calculations are not guaranteed to be consistent between machines or even between instances"

Well yes, you've answered your own question! So that's good news.

"Therefore, I need to take that into consideration when I build the architecture that is supposed to handle de-synchronizations between clients caused by floating point errors."

I guess I would say, every single thing - every time, every unit, every frame, every concept - is going to be "desynchronized" and predictive RT $$anonymous$$P strategies involve, are all about, their raison d'etre is, to make the game still look O$$anonymous$$ and work logically, even though (the best way I have heard it expressed) everything is a smear.