Read its server values

This page has a C++ twin: Read its server values, from C++.

The values the server owns about a player or a creature, such as health, loot or a team's orders, are what is true. They cannot live on an actor for a crowd row, because a crowd row has no actor. They live in a Server Object that keeps a record per entity, and a row reads its own record in place. Nothing is copied into a fragment, and nothing runs per row per frame: the work is one pass over a batch of changed records.

The Server Object type and its server code are on Keep a record per entity, and this page does not repeat them. It covers what a crowd adds: the setup on the entity's class, and the nodes a row uses.

When you need this

• To show a value on a player or creature you are looking at: a health bar over a raider.
• To react when a value changes: a bar that moves, a marker that appears.

The pose, the torch and the wave are view state. A modified client can lie about them, and the worst it can do is change what you see. A server value is the truth, and a player may only read what the server chose to send them.

Set up the class

On the Oakford north road, the raiders are BP_Raider, keeping a record each in CSO_Raider (see Raiders on the north road). On a Mass map the players who watch the road draw each raider as a crowd row, and a row reads the same record.

1. Make the type. A Server Object definition with Holds set to A Record per Entity, whose server code adds a record for each entity, keyed by the entity's id. Each variable is Server Only, Everyone, Owner Only or Team Only. CSO_Raider has Health for Everyone, Loot for Owner Only and Hideout for Team Only.

2. Put the component on the class. The entity's actor class carries a Crowdy Server Object component whose Definition is that type. It can be native, in the Blueprint, or inherited. The SDK reads it once for the class, from the class default object. BP_Raider has one with Definition CSO_Raider. See Add the component.

3. Pick the object with the component's Instance Mode. Rows follow only a mode that is the same for the whole class:

   Instance Mode	What the rows read
   Only One Instance (a setting of the type)	The type's one object. It wins over every Instance Mode.
   Instance Id, with an id typed	The object with that id.
   This Actor's Area	The objects of the areas around the local view.

   With Signed-In Player, This Actor, Player's Team or From Server Value, the rows get no server values, and the log says why once for the class.

4. Use the entity's id as the record id. A row's record is the one whose id is the entity's UUID as 32 hex digits, the form a census of the world reports as uuid.

With This Actor's Area, the game follows the areas within the type's Areas Followed Around a Player of the local player's pawn or camera, and moves them as the view moves. A value of 1 means the 3 by 3 areas around the view. It lets go of an area only when the view is more than that radius plus one away, so a border does not flap. With no pawn or camera to follow, no area is followed and the rows read nothing.

Read a value

Get Server Value is in the category Crowdy Mass|Server Values. Its pins are Target, Name and Value.

1. Get a target of a raider with a trace. You may check it with Is Crowdy Mass Target Live first; the graph below leaves that out to stay short.
2. Add the H key event, and from Pressed add Get Server Value. Wire TracedTarget into Target.
3. Type Health into Name. It is the variable's name in the asset.
4. Add an Integer variable named Health to the Blueprint, then drag it in and choose Set Health. Connect Value to it. The pin takes the type of whatever you connect.
5. Connect the node's return value to a Branch. Use Value only when the node returns true.
6. From True, add Set Light Color with the Torch light component of the player as its target. Connect a Select Color to New Light Color, with red in A and white in B.
7. Get Health, connect it to a <= node with 10 in its second input, and connect the result to the Pick A pin of Select Color. The torch turns red at 10 health or less, and white otherwise.

Loading Blueprint...

H, Get Server Value (Health), Set Health, Branch, Set Light Color on Torch (red at 10 or less)Download .txt

Pan a Blueprint figure with the right mouse button. Press Copy nodes, then Ctrl+V in your own event graph.

The node returns true only for a value the server sent that fits the type of Value. The server never sends a value the player may not receive, such as an Owner Only value of an entity they do not own. The node returns false for it.

React to a change

Receive Server Values Changed on Entity is the twin of Receive Crowdy Event on Entity. It runs part of a graph whenever the server values of a row change.

1. Open an event graph. The node cannot go in a function or macro graph.
2. Add Receive Server Values Changed on Entity (category Crowdy Mass|Server Values).
3. Set Entity Class to BP_Raider. The node listens to rows of that class and its subclasses. The node is an error without a class, and a warning if the class has no Crowdy Server Object component that reads a record per entity.
4. Wire Event BeginPlay into Bind. If nothing runs into Bind the compiler warns that the node is never reached.
5. From On Changed, use Target and Changed. Call Get Server Value on Target for each variable you care about.

Pin	Direction	What it is
Bind	in, exec	Start listening.
Unbind	in, exec	Stop listening. The binding also ends when the object or its world goes away.
Entity Class	in	The actor class whose crowd rows are listened to, with its subclasses.
Then	out, exec	Continues as soon as the bind or unbind is done.
On Changed	out, exec	Runs for each change of a row of that class.
Target	out	The row.
Changed	out	An array of strings: the variables that changed, as Get Server Value takes them. Empty when the entity's record was removed.

A record can arrive before its row exists. The record is kept, and the event runs once, with the current values, when the row appears. A row that moves from one followed area into the next does not see its record removed and added again.

A near tier actor

A class that promotes to the near tier (see Promote close entities to actors) reads and hears the same values through its Crowdy Mass Near Tier component, UCrowdyMassNearTierComponent. Both answer for the entity the near tier actor stands in for, so the actor and its row never disagree.

• Get Server Value on the component has the pins Name and Value. It reads the bound entity's variable.
• On Server Values Changed is an event on the component with a Changed array. In BP_LanternPlayer_Shell, select the Crowdy Mass Near Tier component and click the plus beside the event in the Details panel.

Gotchas

• Read to draw. The values are the server's. Change them by calling a Server Function, not from here.
• Owner Only and Team Only values arrive later than Everyone values, because they are fetched, at most once a second for each followed area.
• The first values are not instant. A row drawn the moment a player enters an area reads nothing until the object has been read.
• A class stays followed for the life of the world once a row of it has been seen.
• A row gets no values. Work through the checklist on Fix a crowd that does not look right.

Related

• Keep a record per entity: the type, the audience of a variable and the server code
• Raiders on the north road: the record per raider this page reads
• Target an entity: get the target Get Server Value takes
• Promote close entities to actors: the near tier
• Fix a crowd that does not look right: the checklist for a row that gets no values
• Read its server values, from C++: the same reads in code