Sync

In a single-player game it does nothing. On a server it is the only way to show everybody the same number

hardYou need: What a world processor is, Raise a flag

sync count

One variable in one field — and its value travels to everybody playing on this map.

Note

In a single-player game the instruction does nothing — that is the game’s own behaviour, there is nobody to broadcast to. The course sandbox has no network, so there is no example for this lesson.

What it is for on a server

On a server the map is computed once — on the server. Clients see a copy of it, and in that copy processors’ variables are empty: the server does not broadcast them, because there are hundreds of them and they change every tick.

Usually that is not needed: a client sees blocks, units and messages. But if a script wants a client to read a value — a player’s display drawing a score from a processor’s variable, say — the value has to be broadcast explicitly. That is what sync does.

Twenty times a second, no more

Every variable has its own timer: it can be sent once every 50 milliseconds. Anything a program tries to send more often simply is not sent — no error and no queue.

Note

The limit is on the variable, not on the instruction. Twenty different variables broadcast freely; the same one in a loop, only twenty times a second.

Silent failure

A constant cannot be broadcast. sync @copper or sync 5 do nothing: only real program variables are sent.

Which to choose: sync or a flag

	sync	a global flag
what it carries	any value	“yes” or “no”
to whom	every client	processors and the map’s objectives
how often	20 times a second per variable	no limit

Flags are about a script’s logic, sync is about what the player sees. A number on a display, a countdown to a wave, a team’s score: everything a client reads from a processor’s variable needs broadcasting.

Remember

• sync variable broadcasts its value to clients.
• In a single-player game it does nothing.
• The limit is twenty sends a second per variable.
• Constants are not broadcast.
• A script’s logic usually manages with flags; sync is for the clients’ sake.