ACSUtils Wiki

An ACS library for ZDoom-based ports

User Tools

Site Tools

Trace:
client_server_detection

Differences

This shows you the differences between two versions of the page.

Link to this comparison view

Both sides previous revisionPrevious revision
Next revision		Previous revision
Next revisionBoth sides next revision
client_server_detection [2019/08/26 04:04] – korshunclient_server_detection [2019/09/05 23:46] – [How it works] korshun
Line 1: Line 1:
-====== Clientside/Serverside detection ======+====== Clientside/serverside detection ====== 
 + 
 +===== Introduction =====
  
 You can check if a script is running serverside, clientside or in singleplayer using functions provided by ACSUtils. You can check if a script is running serverside, clientside or in singleplayer using functions provided by ACSUtils.
 +
  
 ===== Terminology ===== ===== Terminology =====
  
   * **Server** -- an engine instance that runs the gameplay code.   * **Server** -- an engine instance that runs the gameplay code.
-  * **Client** -- an engine instance that runs the rendering code and provides input to the server.+  * **Client** -- an engine instance that runs the rendering code and controls a player on the server.
  
 In singleplayer, the same engine instance is **both a server and a client**. Both ''IsServer()'' and ''IsClient()'' return true in singleplayer. In singleplayer, the same engine instance is **both a server and a client**. Both ''IsServer()'' and ''IsClient()'' return true in singleplayer.
  
 In ZDoom and GZDoom multiplayer (but not Zandronum's), all players are both servers and clients, just like in singleplayer. In ZDoom and GZDoom multiplayer (but not Zandronum's), all players are both servers and clients, just like in singleplayer.
 +
 +Zandronum multiplayer emulation is singleplayer. Just like in singleplayer, the same engine instance is both a server and a client.
 +
 +In real Zandronum multiplayer, the server is only a server and clients are only clients, obviously.
 +
 +Yet, if Zandronum were to allow hosting non-dedicated servers, where a player allows others to connect to their singleplayer game without launching a separate engine instance, the hosting player would be both a server and a client, while other players in the game would be only clients.
 +
  
 ===== Functions ===== ===== Functions =====
Line 23: Line 33:
 ===== Writing robust multiplayer code ===== ===== Writing robust multiplayer code =====
  
-The definitions above enable writing ACS code that functions correctly in both singleplayer and multiplayer without singleplayer being a special case.+The definitions above enable writing ACS code that functions correctly in both singleplayer and multiplayer without singleplayer being a special case. Using ''IsClient'' and ''IsServer'' correctly ensures that your mod runs correctly in both singleplayer and multiplayer: 
 + 
 +<code acs> 
 +if (IsServer()) 
 +{ 
 +    // Run serverside gameplay code. 
 +} 
 +if (IsClient()) 
 +{ 
 +    // Draw hud, spawn effects. 
 +} 
 +</code> 
 + 
 +===== How it works ===== 
 + 
 +All detection of clients and servers is founded on two functions: [[zdoom>ConsolePlayerNumber]] and [[zan>IsNetworkGame]] (formerly known as ''IsMultiplayer''). 
 + 
 +''IsClient()'' simply checks if [[zdoom>ConsolePlayerNumber]] is not negative. 
 + 
 +''IsServer()'' is more complicated. It returns true if [[zdoom>ConsolePlayerNumber]] is negative. But if it's not negative, it needs to distinguish between multiplayer emulation and real multiplayer. It checks if the multiplayer is real using [[zan>IsNetworkGame]]. But calling this function in ZDoom/GZDoom crashes the engine. Therefore, before calling ''IsNetworkGame'', it checks if the engine is Zandronum using [[source_port_detection|IsZandronum]]. 
 + 
 +If the engine is not Zandronum, the function returns true, because in ZDoom/GZDoom all players run gameplay code. 
 + 
 +If the engine is Zandronum, the function returns false if it's real multiplayer, true if it's multiplayer emulation.
  
 +''IsServerOnly'' and ''IsClientOnly'' simply return ''IsServer() && !IsClient()'' and ''IsClient() && !IsServer()'', respectively.
  
client_server_detection.txt · Last modified: 2019/09/05 23:54 by korshun

Page Tools

Flag Counter