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Chapter 8.8: Building a HUD Overlay ​

Home | << Previous: Publishing to the Steam Workshop | Building a HUD Overlay | Next: Professional Mod Template >>

Summary: This tutorial walks you through building a custom HUD overlay that displays server information in the top-right corner of the screen. You will create a layout file, write a controller class, hook into the mission lifecycle, request data from the server via RPC, add a toggle keybind, and polish the result with fade animations and smart visibility. By the end, you will have a non-intrusive Server Info HUD showing the server name, player count, and current in-game time -- plus a solid understanding of how HUD overlays work in DayZ.

Table of Contents ​

What We Are Building ​

A small, semi-transparent panel anchored to the top-right corner of the screen that displays three lines of information:

  Aurora Survival [Official]
  Players: 24 / 60
  Time: 14:35

The panel sits below the status indicators and above the quickbar. It updates once per second (not every frame), fades in when shown and fades out when hidden, and automatically hides when the inventory or pause menu is open. The player can toggle it on and off with a configurable key (default: F7).

Expected Result ​

When loaded, you will see a dark semi-transparent rectangle in the top-right area of the screen. White text shows the server name on the first line, the current player count on the second line, and the in-game world time on the third line. Pressing F7 smoothly fades it out; pressing F7 again fades it back in.

Prerequisites ​

  • A working mod structure (complete Chapter 8.1 first)
  • Basic understanding of Enforce Script syntax
  • Familiarity with DayZ's client-server model (the HUD runs on the client; player count comes from the server)

Mod Structure ​

Create the following directory tree:

ServerInfoHUD/
    mod.cpp
    Scripts/
        config.cpp
        data/
            inputs.xml
        3_Game/
            ServerInfoHUD/
                ServerInfoRPC.c
        4_World/
            ServerInfoHUD/
                ServerInfoServer.c
        5_Mission/
            ServerInfoHUD/
                ServerInfoHUD.c
                MissionHook.c
    GUI/
        layouts/
            ServerInfoHUD.layout

The 3_Game layer defines constants (our RPC ID). The 4_World layer handles the server-side response. The 5_Mission layer contains the HUD class and the mission hook. The layout file defines the widget tree.

Step 1: Create the Layout File ​

Layout files (.layout) define the widget hierarchy in XML. DayZ's GUI system uses a coordinate model where each widget has a position and size expressed as proportional values (0.0 to 1.0 of the parent) plus pixel offsets.

GUI/layouts/ServerInfoHUD.layout ​

xml
<?xml version="1.0" encoding="UTF-8"?>
<layoutset>
  <children>
    <!-- Root frame: covers the full screen, does not consume input -->
    <Widget name="ServerInfoRoot" type="FrameWidgetClass">
      <Attribute name="position" value="0 0" />
      <Attribute name="size" value="1 1" />
      <Attribute name="halign" value="0" />
      <Attribute name="valign" value="0" />
      <Attribute name="hexactpos" value="0" />
      <Attribute name="vexactpos" value="0" />
      <Attribute name="hexactsize" value="0" />
      <Attribute name="vexactsize" value="0" />
      <children>
        <!-- Background panel: top-right corner -->
        <Widget name="ServerInfoPanel" type="ImageWidgetClass">
          <Attribute name="position" value="1 0" />
          <Attribute name="size" value="220 70" />
          <Attribute name="halign" value="2" />
          <Attribute name="valign" value="0" />
          <Attribute name="hexactpos" value="0" />
          <Attribute name="vexactpos" value="1" />
          <Attribute name="hexactsize" value="1" />
          <Attribute name="vexactsize" value="1" />
          <Attribute name="color" value="0 0 0 0.55" />
          <children>
            <!-- Server name text -->
            <Widget name="ServerNameText" type="TextWidgetClass">
              <Attribute name="position" value="8 6" />
              <Attribute name="size" value="204 20" />
              <Attribute name="hexactpos" value="1" />
              <Attribute name="vexactpos" value="1" />
              <Attribute name="hexactsize" value="1" />
              <Attribute name="vexactsize" value="1" />
              <Attribute name="font" value="gui/fonts/MetronBook" />
              <Attribute name="fontsize" value="14" />
              <Attribute name="text" value="Server Name" />
              <Attribute name="color" value="1 1 1 0.9" />
              <Attribute name="halign" value="0" />
              <Attribute name="valign" value="0" />
            </Widget>
            <!-- Player count text -->
            <Widget name="PlayerCountText" type="TextWidgetClass">
              <Attribute name="position" value="8 28" />
              <Attribute name="size" value="204 18" />
              <Attribute name="hexactpos" value="1" />
              <Attribute name="vexactpos" value="1" />
              <Attribute name="hexactsize" value="1" />
              <Attribute name="vexactsize" value="1" />
              <Attribute name="font" value="gui/fonts/MetronBook" />
              <Attribute name="fontsize" value="12" />
              <Attribute name="text" value="Players: - / -" />
              <Attribute name="color" value="0.8 0.8 0.8 0.85" />
              <Attribute name="halign" value="0" />
              <Attribute name="valign" value="0" />
            </Widget>
            <!-- In-game time text -->
            <Widget name="TimeText" type="TextWidgetClass">
              <Attribute name="position" value="8 48" />
              <Attribute name="size" value="204 18" />
              <Attribute name="hexactpos" value="1" />
              <Attribute name="vexactpos" value="1" />
              <Attribute name="hexactsize" value="1" />
              <Attribute name="vexactsize" value="1" />
              <Attribute name="font" value="gui/fonts/MetronBook" />
              <Attribute name="fontsize" value="12" />
              <Attribute name="text" value="Time: --:--" />
              <Attribute name="color" value="0.8 0.8 0.8 0.85" />
              <Attribute name="halign" value="0" />
              <Attribute name="valign" value="0" />
            </Widget>
          </children>
        </Widget>
      </children>
    </Widget>
  </children>
</layoutset>

Key Layout Concepts ​

AttributeMeaning
halign="2"Horizontal alignment: right. The widget anchors to the right edge of its parent.
valign="0"Vertical alignment: top.
hexactpos="0" + vexactpos="1"Horizontal position is proportional (1.0 = right edge), vertical position is in pixels.
hexactsize="1" + vexactsize="1"Width and height are in pixels (220 x 70).
color="0 0 0 0.55"RGBA as floats. Black at 55% opacity for the background panel.

The ServerInfoPanel is positioned at proportional X=1.0 (right edge) with halign="2" (right-aligned), so the panel's right edge touches the right side of the screen. The Y position is 0 pixels from the top. This places our HUD in the top-right corner.

Why pixel sizes for the panel? Proportional sizing would make the panel scale with resolution, but for small info widgets you want a fixed pixel footprint so the text stays readable at all resolutions.

Step 2: Create the HUD Controller Class ​

The controller class loads the layout, finds widgets by name, and exposes methods to update the displayed text. It extends ScriptedWidgetEventHandler so it can receive widget events if needed later.

Scripts/5_Mission/ServerInfoHUD/ServerInfoHUD.c ​

c
class ServerInfoHUD : ScriptedWidgetEventHandler
{
    protected Widget m_Root;
    protected Widget m_Panel;
    protected TextWidget m_ServerNameText;
    protected TextWidget m_PlayerCountText;
    protected TextWidget m_TimeText;

    protected bool m_IsVisible;
    protected float m_UpdateTimer;

    // How often to refresh displayed data (seconds)
    static const float UPDATE_INTERVAL = 1.0;

    void ServerInfoHUD()
    {
        m_IsVisible = true;
        m_UpdateTimer = 0;
    }

    void ~ServerInfoHUD()
    {
        Destroy();
    }

    // Create and show the HUD
    void Init()
    {
        if (m_Root)
            return;

        m_Root = GetGame().GetWorkspace().CreateWidgets(
            "ServerInfoHUD/GUI/layouts/ServerInfoHUD.layout"
        );

        if (!m_Root)
        {
            Print("[ServerInfoHUD] ERROR: Failed to load layout file.");
            return;
        }

        m_Panel = m_Root.FindAnyWidget("ServerInfoPanel");
        m_ServerNameText = TextWidget.Cast(
            m_Root.FindAnyWidget("ServerNameText")
        );
        m_PlayerCountText = TextWidget.Cast(
            m_Root.FindAnyWidget("PlayerCountText")
        );
        m_TimeText = TextWidget.Cast(
            m_Root.FindAnyWidget("TimeText")
        );

        m_Root.Show(true);
        m_IsVisible = true;

        // Request initial data from server
        RequestServerInfo();
    }

    // Remove all widgets
    void Destroy()
    {
        if (m_Root)
        {
            m_Root.Unlink();
            m_Root = NULL;
        }
    }

    // Called every frame from MissionGameplay.OnUpdate
    void Update(float timeslice)
    {
        if (!m_Root)
            return;

        if (!m_IsVisible)
            return;

        m_UpdateTimer += timeslice;

        if (m_UpdateTimer >= UPDATE_INTERVAL)
        {
            m_UpdateTimer = 0;
            RefreshTime();
            RequestServerInfo();
        }
    }

    // Update the in-game time display (client-side, no RPC needed)
    protected void RefreshTime()
    {
        if (!m_TimeText)
            return;

        int year, month, day, hour, minute;
        GetGame().GetWorld().GetDate(year, month, day, hour, minute);

        string hourStr = hour.ToString();
        string minStr = minute.ToString();

        if (hour < 10)
            hourStr = "0" + hourStr;

        if (minute < 10)
            minStr = "0" + minStr;

        m_TimeText.SetText("Time: " + hourStr + ":" + minStr);
    }

    // Send RPC to server asking for player count and server name
    protected void RequestServerInfo()
    {
        if (!GetGame().IsMultiplayer())
        {
            // Offline mode: just show local info
            SetServerName("Offline Mode");
            SetPlayerCount(1, 1);
            return;
        }

        Man player = GetGame().GetPlayer();
        if (!player)
            return;

        ScriptRPC rpc = new ScriptRPC();
        rpc.Send(player, SIH_RPC_REQUEST_INFO, true, NULL);
    }

    // --- Setters called when data arrives ---

    void SetServerName(string name)
    {
        if (m_ServerNameText)
            m_ServerNameText.SetText(name);
    }

    void SetPlayerCount(int current, int max)
    {
        if (m_PlayerCountText)
        {
            string text = "Players: " + current.ToString()
                + " / " + max.ToString();
            m_PlayerCountText.SetText(text);
        }
    }

    // Toggle visibility
    void ToggleVisibility()
    {
        m_IsVisible = !m_IsVisible;

        if (m_Root)
            m_Root.Show(m_IsVisible);
    }

    // Hide when menus are open
    void SetMenuState(bool menuOpen)
    {
        if (!m_Root)
            return;

        if (menuOpen)
        {
            m_Root.Show(false);
        }
        else if (m_IsVisible)
        {
            m_Root.Show(true);
        }
    }

    bool IsVisible()
    {
        return m_IsVisible;
    }

    Widget GetRoot()
    {
        return m_Root;
    }
};

Important Details ​

  1. CreateWidgets path: The path is relative to the mod root. Since we pack the GUI/ folder inside the PBO, the engine resolves ServerInfoHUD/GUI/layouts/ServerInfoHUD.layout using the mod prefix.
  2. FindAnyWidget: Searches the widget tree recursively by name. Always check for NULL after casting.
  3. Widget.Unlink(): Properly removes the widget and all its children from the UI tree. Always call this in cleanup.
  4. Timer accumulator pattern: We add timeslice each frame and act only when the accumulated time exceeds UPDATE_INTERVAL. This prevents doing work every single frame.

Step 3: Hook into MissionGameplay ​

The MissionGameplay class is the mission controller on the client side. We use modded class to inject our HUD into its lifecycle without replacing the vanilla file.

Scripts/5_Mission/ServerInfoHUD/MissionHook.c ​

c
modded class MissionGameplay
{
    protected ref ServerInfoHUD m_ServerInfoHUD;

    override void OnInit()
    {
        super.OnInit();

        // Create the HUD overlay
        m_ServerInfoHUD = new ServerInfoHUD();
        m_ServerInfoHUD.Init();
    }

    override void OnMissionFinish()
    {
        // Clean up BEFORE calling super
        if (m_ServerInfoHUD)
        {
            m_ServerInfoHUD.Destroy();
            m_ServerInfoHUD = NULL;
        }

        super.OnMissionFinish();
    }

    override void OnUpdate(float timeslice)
    {
        super.OnUpdate(timeslice);

        if (!m_ServerInfoHUD)
            return;

        // Hide HUD when inventory or any menu is open
        UIManager uiMgr = GetGame().GetUIManager();
        bool menuOpen = false;

        if (uiMgr)
        {
            UIScriptedMenu topMenu = uiMgr.GetMenu();
            if (topMenu)
                menuOpen = true;
        }

        m_ServerInfoHUD.SetMenuState(menuOpen);

        // Update HUD data (throttled internally)
        m_ServerInfoHUD.Update(timeslice);

        // Check toggle key
        Input input = GetGame().GetInput();
        if (input)
        {
            if (GetUApi().GetInputByName("UAServerInfoToggle").LocalPress())
            {
                m_ServerInfoHUD.ToggleVisibility();
            }
        }
    }

    // Accessor so the RPC handler can reach the HUD
    ServerInfoHUD GetServerInfoHUD()
    {
        return m_ServerInfoHUD;
    }
};

Why This Pattern Works ​

  • OnInit runs once when the player enters gameplay. We create and initialize the HUD here.
  • OnUpdate runs every frame. We pass timeslice to the HUD, which internally throttles to once per second. We also check for the toggle key press and menu visibility here.
  • OnMissionFinish runs when the player disconnects or the mission ends. We destroy our widgets here to prevent memory leaks.

Critical Rule: Always Clean Up ​

If you forget to destroy your widgets in OnMissionFinish, the widget root will leak into the next session. After a few server hops, the player ends up with stacked ghost widgets consuming memory. Always pair Init() with Destroy().

Step 4: Request Data from Server ​

The player count is only known on the server. We need a simple RPC (Remote Procedure Call) round-trip: the client sends a request, the server reads the data and sends it back.

Step 4a: Define the RPC ID ​

RPC IDs must be unique across all mods. We define ours in the 3_Game layer so both client and server code can reference it.

Scripts/3_Game/ServerInfoHUD/ServerInfoRPC.c ​

c
// RPC IDs for the Server Info HUD.
// Using high numbers to avoid conflicts with vanilla and other mods.

const int SIH_RPC_REQUEST_INFO = 72810;
const int SIH_RPC_RESPONSE_INFO = 72811;

Why 3_Game? Constants and enums belong in the lowest layer that both client and server can access. The 3_Game layer loads before 4_World and 5_Mission, so both sides can see these values.

Step 4b: Server-Side Handler ​

The server listens for SIH_RPC_REQUEST_INFO, gathers the data, and responds with SIH_RPC_RESPONSE_INFO.

Scripts/4_World/ServerInfoHUD/ServerInfoServer.c ​

c
modded class PlayerBase
{
    override void OnRPC(
        PlayerIdentity sender,
        int rpc_type,
        ParamsReadContext ctx
    )
    {
        super.OnRPC(sender, rpc_type, ctx);

        if (!GetGame().IsServer())
            return;

        if (rpc_type == SIH_RPC_REQUEST_INFO)
        {
            HandleServerInfoRequest(sender);
        }
    }

    protected void HandleServerInfoRequest(PlayerIdentity sender)
    {
        if (!sender)
            return;

        // Gather server info
        string serverName = "";
        GetGame().GetHostName(serverName);

        int playerCount = 0;
        int maxPlayers = 0;

        // Get the player list
        ref array<Man> players = new array<Man>();
        GetGame().GetPlayers(players);
        playerCount = players.Count();

        // Max players from server config
        maxPlayers = GetGame().GetMaxPlayers();

        // Send response back to the requesting client
        ScriptRPC rpc = new ScriptRPC();
        rpc.Write(serverName);
        rpc.Write(playerCount);
        rpc.Write(maxPlayers);
        rpc.Send(this, SIH_RPC_RESPONSE_INFO, true, sender);
    }
};

Step 4c: Client-Side RPC Receiver ​

The client receives the response and updates the HUD.

Add this to the same ServerInfoHUD.c file (at the bottom, outside the class), or create a separate file in 5_Mission/ServerInfoHUD/:

Add the following below the ServerInfoHUD class in ServerInfoHUD.c:

c
modded class PlayerBase
{
    override void OnRPC(
        PlayerIdentity sender,
        int rpc_type,
        ParamsReadContext ctx
    )
    {
        super.OnRPC(sender, rpc_type, ctx);

        if (GetGame().IsServer())
            return;

        if (rpc_type == SIH_RPC_RESPONSE_INFO)
        {
            HandleServerInfoResponse(ctx);
        }
    }

    protected void HandleServerInfoResponse(ParamsReadContext ctx)
    {
        string serverName;
        int playerCount;
        int maxPlayers;

        if (!ctx.Read(serverName))
            return;
        if (!ctx.Read(playerCount))
            return;
        if (!ctx.Read(maxPlayers))
            return;

        // Access the HUD through MissionGameplay
        MissionGameplay mission = MissionGameplay.Cast(
            GetGame().GetMission()
        );

        if (!mission)
            return;

        ServerInfoHUD hud = mission.GetServerInfoHUD();
        if (!hud)
            return;

        hud.SetServerName(serverName);
        hud.SetPlayerCount(playerCount, maxPlayers);
    }
};

How the RPC Flow Works ​

CLIENT                           SERVER
  |                                |
  |--- SIH_RPC_REQUEST_INFO ----->|
  |                                | reads serverName, playerCount, maxPlayers
  |<-- SIH_RPC_RESPONSE_INFO ----|
  |                                |
  | updates HUD text              |

The client sends the request once per second (throttled by the update timer). The server responds with three values packed into the RPC context. The client reads them in the same order they were written.

Important: rpc.Write() and ctx.Read() must use the same types in the same order. If the server writes a string then two int values, the client must read a string then two int values.

Step 5: Add Toggle with Keybind ​

Step 5a: Define the Input in inputs.xml ​

DayZ uses inputs.xml to register custom key actions. The file must be placed in Scripts/data/inputs.xml and referenced from config.cpp.

Scripts/data/inputs.xml ​

xml
<?xml version="1.0" encoding="UTF-8" standalone="yes" ?>
<modded_inputs>
    <inputs>
        <actions>
            <input name="UAServerInfoToggle" loc="Toggle Server Info HUD" />
        </actions>
    </inputs>
    <preset>
        <input name="UAServerInfoToggle">
            <btn name="kF7" />
        </input>
    </preset>
</modded_inputs>
ElementPurpose
<actions>Declares the input action by name. loc is the display string shown in the keybinding options menu.
<preset>Assigns the default key. kF7 maps to the F7 key.

Step 5b: Reference inputs.xml in config.cpp ​

Your config.cpp must tell the engine where to find the inputs file. Add an inputs entry inside the defs block:

cpp
class defs
{
    class gameScriptModule
    {
        value = "";
        files[] = { "ServerInfoHUD/Scripts/3_Game" };
    };

    class worldScriptModule
    {
        value = "";
        files[] = { "ServerInfoHUD/Scripts/4_World" };
    };

    class missionScriptModule
    {
        value = "";
        files[] = { "ServerInfoHUD/Scripts/5_Mission" };
    };

    class inputs
    {
        value = "";
        files[] = { "ServerInfoHUD/Scripts/data" };
    };
};

Step 5c: Read the Key Press ​

We already handle this in the MissionGameplay hook from Step 3:

c
if (GetUApi().GetInputByName("UAServerInfoToggle").LocalPress())
{
    m_ServerInfoHUD.ToggleVisibility();
}

GetUApi() returns the input API singleton. GetInputByName looks up our registered action. LocalPress() returns true for exactly one frame when the key is pressed down.

Key Name Reference ​

Common key names for <btn>:

Key NameKey
kF1 through kF12Function keys
kH, kI, etc.Letter keys
kNumpad0 through kNumpad9Numpad
kLControlLeft Control
kLShiftLeft Shift
kLAltLeft Alt

Modifier combos use nesting:

xml
<input name="UAServerInfoToggle">
    <btn name="kLControl">
        <btn name="kH" />
    </btn>
</input>

This means "hold Left Control and press H."

Step 6: Polish ​

6a: Fade In/Out Animation ​

DayZ provides WidgetFadeTimer for smooth alpha transitions. Update the ServerInfoHUD class to use it:

c
class ServerInfoHUD : ScriptedWidgetEventHandler
{
    // ... existing fields ...

    protected ref WidgetFadeTimer m_FadeTimer;

    void ServerInfoHUD()
    {
        m_IsVisible = true;
        m_UpdateTimer = 0;
        m_FadeTimer = new WidgetFadeTimer();
    }

    // Replace the ToggleVisibility method:
    void ToggleVisibility()
    {
        m_IsVisible = !m_IsVisible;

        if (!m_Root)
            return;

        if (m_IsVisible)
        {
            m_Root.Show(true);
            m_FadeTimer.FadeIn(m_Root, 0.3);
        }
        else
        {
            m_FadeTimer.FadeOut(m_Root, 0.3);
        }
    }

    // ... rest of class ...
};

FadeIn(widget, duration) animates the widget's alpha from 0 to 1 over the given duration in seconds. FadeOut goes from 1 to 0 and hides the widget when done.

6b: Background Panel with Alpha ​

We already set this in the layout (color="0 0 0 0.55"), giving a dark overlay at 55% opacity. If you want to adjust the alpha at runtime:

c
void SetBackgroundAlpha(float alpha)
{
    if (m_Panel)
    {
        int color = ARGB(
            (int)(alpha * 255),
            0, 0, 0
        );
        m_Panel.SetColor(color);
    }
}

The ARGB() function takes integer values 0-255 for alpha, red, green, and blue.

6c: Font and Color Choices ​

DayZ ships several fonts you can reference in layouts:

Font PathStyle
gui/fonts/MetronBookClean sans-serif (used in vanilla HUD)
gui/fonts/MetronMediumBolder version of MetronBook
gui/fonts/MetronThinnest variant
gui/fonts/luxuriousscriptDecorative script (avoid for HUD)

To change text color at runtime:

c
void SetTextColor(TextWidget widget, int r, int g, int b, int a)
{
    if (widget)
        widget.SetColor(ARGB(a, r, g, b));
}

6d: Respecting Other UI ​

Our MissionHook.c already detects when a menu is open and calls SetMenuState(true). Here is a more thorough approach that checks the inventory specifically:

c
// In the OnUpdate override of modded MissionGameplay:
bool menuOpen = false;

UIManager uiMgr = GetGame().GetUIManager();
if (uiMgr)
{
    UIScriptedMenu topMenu = uiMgr.GetMenu();
    if (topMenu)
        menuOpen = true;
}

// Also check if inventory is open
if (uiMgr && uiMgr.FindMenu(MENU_INVENTORY))
    menuOpen = true;

m_ServerInfoHUD.SetMenuState(menuOpen);

This ensures your HUD hides behind the inventory screen, the pause menu, the options screen, and any other scripted menu.

Complete Code Reference ​

Below is every file in the mod, in its final form with all polish applied.

File 1: ServerInfoHUD/mod.cpp ​

cpp
name = "Server Info HUD";
author = "YourName";
version = "1.0";
overview = "Displays server name, player count, and in-game time.";

File 2: ServerInfoHUD/Scripts/config.cpp ​

cpp
class CfgPatches
{
    class ServerInfoHUD_Scripts
    {
        units[] = {};
        weapons[] = {};
        requiredVersion = 0.1;
        requiredAddons[] =
        {
            "DZ_Data",
            "DZ_Scripts"
        };
    };
};

class CfgMods
{
    class ServerInfoHUD
    {
        dir = "ServerInfoHUD";
        name = "Server Info HUD";
        author = "YourName";
        type = "mod";

        dependencies[] = { "Game", "World", "Mission" };

        class defs
        {
            class gameScriptModule
            {
                value = "";
                files[] = { "ServerInfoHUD/Scripts/3_Game" };
            };

            class worldScriptModule
            {
                value = "";
                files[] = { "ServerInfoHUD/Scripts/4_World" };
            };

            class missionScriptModule
            {
                value = "";
                files[] = { "ServerInfoHUD/Scripts/5_Mission" };
            };

            class inputs
            {
                value = "";
                files[] = { "ServerInfoHUD/Scripts/data" };
            };
        };
    };
};

File 3: ServerInfoHUD/Scripts/data/inputs.xml ​

xml
<?xml version="1.0" encoding="UTF-8" standalone="yes" ?>
<modded_inputs>
    <inputs>
        <actions>
            <input name="UAServerInfoToggle" loc="Toggle Server Info HUD" />
        </actions>
    </inputs>
    <preset>
        <input name="UAServerInfoToggle">
            <btn name="kF7" />
        </input>
    </preset>
</modded_inputs>

File 4: ServerInfoHUD/Scripts/3_Game/ServerInfoHUD/ServerInfoRPC.c ​

c
// RPC IDs for Server Info HUD.
// Use high numbers to avoid collisions with vanilla ERPCs and other mods.

const int SIH_RPC_REQUEST_INFO = 72810;
const int SIH_RPC_RESPONSE_INFO = 72811;

File 5: ServerInfoHUD/Scripts/4_World/ServerInfoHUD/ServerInfoServer.c ​

c
modded class PlayerBase
{
    override void OnRPC(
        PlayerIdentity sender,
        int rpc_type,
        ParamsReadContext ctx
    )
    {
        super.OnRPC(sender, rpc_type, ctx);

        // Only the server handles this RPC
        if (!GetGame().IsServer())
            return;

        if (rpc_type == SIH_RPC_REQUEST_INFO)
        {
            HandleServerInfoRequest(sender);
        }
    }

    protected void HandleServerInfoRequest(PlayerIdentity sender)
    {
        if (!sender)
            return;

        // Get server name
        string serverName = "";
        GetGame().GetHostName(serverName);

        // Count players
        ref array<Man> players = new array<Man>();
        GetGame().GetPlayers(players);
        int playerCount = players.Count();

        // Get max player slots
        int maxPlayers = GetGame().GetMaxPlayers();

        // Send the data back to the requesting client
        ScriptRPC rpc = new ScriptRPC();
        rpc.Write(serverName);
        rpc.Write(playerCount);
        rpc.Write(maxPlayers);
        rpc.Send(this, SIH_RPC_RESPONSE_INFO, true, sender);
    }
};

File 6: ServerInfoHUD/Scripts/5_Mission/ServerInfoHUD/ServerInfoHUD.c ​

c
class ServerInfoHUD : ScriptedWidgetEventHandler
{
    protected Widget m_Root;
    protected Widget m_Panel;
    protected TextWidget m_ServerNameText;
    protected TextWidget m_PlayerCountText;
    protected TextWidget m_TimeText;

    protected bool m_IsVisible;
    protected float m_UpdateTimer;
    protected ref WidgetFadeTimer m_FadeTimer;

    static const float UPDATE_INTERVAL = 1.0;

    void ServerInfoHUD()
    {
        m_IsVisible = true;
        m_UpdateTimer = 0;
        m_FadeTimer = new WidgetFadeTimer();
    }

    void ~ServerInfoHUD()
    {
        Destroy();
    }

    void Init()
    {
        if (m_Root)
            return;

        m_Root = GetGame().GetWorkspace().CreateWidgets(
            "ServerInfoHUD/GUI/layouts/ServerInfoHUD.layout"
        );

        if (!m_Root)
        {
            Print("[ServerInfoHUD] ERROR: Failed to load layout.");
            return;
        }

        m_Panel = m_Root.FindAnyWidget("ServerInfoPanel");
        m_ServerNameText = TextWidget.Cast(
            m_Root.FindAnyWidget("ServerNameText")
        );
        m_PlayerCountText = TextWidget.Cast(
            m_Root.FindAnyWidget("PlayerCountText")
        );
        m_TimeText = TextWidget.Cast(
            m_Root.FindAnyWidget("TimeText")
        );

        m_Root.Show(true);
        m_IsVisible = true;

        RequestServerInfo();
    }

    void Destroy()
    {
        if (m_Root)
        {
            m_Root.Unlink();
            m_Root = NULL;
        }
    }

    void Update(float timeslice)
    {
        if (!m_Root || !m_IsVisible)
            return;

        m_UpdateTimer += timeslice;

        if (m_UpdateTimer >= UPDATE_INTERVAL)
        {
            m_UpdateTimer = 0;
            RefreshTime();
            RequestServerInfo();
        }
    }

    protected void RefreshTime()
    {
        if (!m_TimeText)
            return;

        int year, month, day, hour, minute;
        GetGame().GetWorld().GetDate(year, month, day, hour, minute);

        string hourStr = hour.ToString();
        string minStr = minute.ToString();

        if (hour < 10)
            hourStr = "0" + hourStr;

        if (minute < 10)
            minStr = "0" + minStr;

        m_TimeText.SetText("Time: " + hourStr + ":" + minStr);
    }

    protected void RequestServerInfo()
    {
        if (!GetGame().IsMultiplayer())
        {
            SetServerName("Offline Mode");
            SetPlayerCount(1, 1);
            return;
        }

        Man player = GetGame().GetPlayer();
        if (!player)
            return;

        ScriptRPC rpc = new ScriptRPC();
        rpc.Send(player, SIH_RPC_REQUEST_INFO, true, NULL);
    }

    void SetServerName(string name)
    {
        if (m_ServerNameText)
            m_ServerNameText.SetText(name);
    }

    void SetPlayerCount(int current, int max)
    {
        if (m_PlayerCountText)
        {
            string text = "Players: " + current.ToString()
                + " / " + max.ToString();
            m_PlayerCountText.SetText(text);
        }
    }

    void ToggleVisibility()
    {
        m_IsVisible = !m_IsVisible;

        if (!m_Root)
            return;

        if (m_IsVisible)
        {
            m_Root.Show(true);
            m_FadeTimer.FadeIn(m_Root, 0.3);
        }
        else
        {
            m_FadeTimer.FadeOut(m_Root, 0.3);
        }
    }

    void SetMenuState(bool menuOpen)
    {
        if (!m_Root)
            return;

        if (menuOpen)
        {
            m_Root.Show(false);
        }
        else if (m_IsVisible)
        {
            m_Root.Show(true);
        }
    }

    bool IsVisible()
    {
        return m_IsVisible;
    }

    Widget GetRoot()
    {
        return m_Root;
    }
};

// -----------------------------------------------
// Client-side RPC receiver
// -----------------------------------------------
modded class PlayerBase
{
    override void OnRPC(
        PlayerIdentity sender,
        int rpc_type,
        ParamsReadContext ctx
    )
    {
        super.OnRPC(sender, rpc_type, ctx);

        if (GetGame().IsServer())
            return;

        if (rpc_type == SIH_RPC_RESPONSE_INFO)
        {
            HandleServerInfoResponse(ctx);
        }
    }

    protected void HandleServerInfoResponse(ParamsReadContext ctx)
    {
        string serverName;
        int playerCount;
        int maxPlayers;

        if (!ctx.Read(serverName))
            return;
        if (!ctx.Read(playerCount))
            return;
        if (!ctx.Read(maxPlayers))
            return;

        MissionGameplay mission = MissionGameplay.Cast(
            GetGame().GetMission()
        );
        if (!mission)
            return;

        ServerInfoHUD hud = mission.GetServerInfoHUD();
        if (!hud)
            return;

        hud.SetServerName(serverName);
        hud.SetPlayerCount(playerCount, maxPlayers);
    }
};

File 7: ServerInfoHUD/Scripts/5_Mission/ServerInfoHUD/MissionHook.c ​

c
modded class MissionGameplay
{
    protected ref ServerInfoHUD m_ServerInfoHUD;

    override void OnInit()
    {
        super.OnInit();

        m_ServerInfoHUD = new ServerInfoHUD();
        m_ServerInfoHUD.Init();
    }

    override void OnMissionFinish()
    {
        if (m_ServerInfoHUD)
        {
            m_ServerInfoHUD.Destroy();
            m_ServerInfoHUD = NULL;
        }

        super.OnMissionFinish();
    }

    override void OnUpdate(float timeslice)
    {
        super.OnUpdate(timeslice);

        if (!m_ServerInfoHUD)
            return;

        // Detect open menus
        bool menuOpen = false;
        UIManager uiMgr = GetGame().GetUIManager();
        if (uiMgr)
        {
            UIScriptedMenu topMenu = uiMgr.GetMenu();
            if (topMenu)
                menuOpen = true;
        }

        m_ServerInfoHUD.SetMenuState(menuOpen);
        m_ServerInfoHUD.Update(timeslice);

        // Toggle key
        if (GetUApi().GetInputByName(
            "UAServerInfoToggle"
        ).LocalPress())
        {
            m_ServerInfoHUD.ToggleVisibility();
        }
    }

    ServerInfoHUD GetServerInfoHUD()
    {
        return m_ServerInfoHUD;
    }
};

File 8: ServerInfoHUD/GUI/layouts/ServerInfoHUD.layout ​

xml
<?xml version="1.0" encoding="UTF-8"?>
<layoutset>
  <children>
    <Widget name="ServerInfoRoot" type="FrameWidgetClass">
      <Attribute name="position" value="0 0" />
      <Attribute name="size" value="1 1" />
      <Attribute name="halign" value="0" />
      <Attribute name="valign" value="0" />
      <Attribute name="hexactpos" value="0" />
      <Attribute name="vexactpos" value="0" />
      <Attribute name="hexactsize" value="0" />
      <Attribute name="vexactsize" value="0" />
      <children>
        <Widget name="ServerInfoPanel" type="ImageWidgetClass">
          <Attribute name="position" value="1 0" />
          <Attribute name="size" value="220 70" />
          <Attribute name="halign" value="2" />
          <Attribute name="valign" value="0" />
          <Attribute name="hexactpos" value="0" />
          <Attribute name="vexactpos" value="1" />
          <Attribute name="hexactsize" value="1" />
          <Attribute name="vexactsize" value="1" />
          <Attribute name="color" value="0 0 0 0.55" />
          <children>
            <Widget name="ServerNameText" type="TextWidgetClass">
              <Attribute name="position" value="8 6" />
              <Attribute name="size" value="204 20" />
              <Attribute name="hexactpos" value="1" />
              <Attribute name="vexactpos" value="1" />
              <Attribute name="hexactsize" value="1" />
              <Attribute name="vexactsize" value="1" />
              <Attribute name="font" value="gui/fonts/MetronBook" />
              <Attribute name="fontsize" value="14" />
              <Attribute name="text" value="Server Name" />
              <Attribute name="color" value="1 1 1 0.9" />
            </Widget>
            <Widget name="PlayerCountText" type="TextWidgetClass">
              <Attribute name="position" value="8 28" />
              <Attribute name="size" value="204 18" />
              <Attribute name="hexactpos" value="1" />
              <Attribute name="vexactpos" value="1" />
              <Attribute name="hexactsize" value="1" />
              <Attribute name="vexactsize" value="1" />
              <Attribute name="font" value="gui/fonts/MetronBook" />
              <Attribute name="fontsize" value="12" />
              <Attribute name="text" value="Players: - / -" />
              <Attribute name="color" value="0.8 0.8 0.8 0.85" />
            </Widget>
            <Widget name="TimeText" type="TextWidgetClass">
              <Attribute name="position" value="8 48" />
              <Attribute name="size" value="204 18" />
              <Attribute name="hexactpos" value="1" />
              <Attribute name="vexactpos" value="1" />
              <Attribute name="hexactsize" value="1" />
              <Attribute name="vexactsize" value="1" />
              <Attribute name="font" value="gui/fonts/MetronBook" />
              <Attribute name="fontsize" value="12" />
              <Attribute name="text" value="Time: --:--" />
              <Attribute name="color" value="0.8 0.8 0.8 0.85" />
            </Widget>
          </children>
        </Widget>
      </children>
    </Widget>
  </children>
</layoutset>

Extending the HUD ​

Once you have the basic HUD working, here are natural extensions.

Adding FPS Display ​

FPS can be read client-side without any RPC:

c
// Add a TextWidget m_FPSText field and find it in Init()

protected void RefreshFPS()
{
    if (!m_FPSText)
        return;

    float fps = 1.0 / GetGame().GetDeltaT();
    m_FPSText.SetText("FPS: " + Math.Round(fps).ToString());
}

Call RefreshFPS() alongside RefreshTime() in the update method. Note that GetDeltaT() returns the time of the current frame, so the FPS value will fluctuate. For a smoother display, average over several frames:

c
protected float m_FPSAccum;
protected int m_FPSFrames;

protected void RefreshFPS()
{
    if (!m_FPSText)
        return;

    m_FPSAccum += GetGame().GetDeltaT();
    m_FPSFrames++;

    float avgFPS = m_FPSFrames / m_FPSAccum;
    m_FPSText.SetText("FPS: " + Math.Round(avgFPS).ToString());

    // Reset every second (when main timer fires)
    m_FPSAccum = 0;
    m_FPSFrames = 0;
}

Adding Player Position ​

c
protected void RefreshPosition()
{
    if (!m_PositionText)
        return;

    Man player = GetGame().GetPlayer();
    if (!player)
        return;

    vector pos = player.GetPosition();
    string text = "Pos: " + Math.Round(pos[0]).ToString()
        + " / " + Math.Round(pos[2]).ToString();
    m_PositionText.SetText(text);
}

Multiple HUD Panels ​

For multiple panels (compass, status, minimap), create a parent manager class that holds an array of HUD elements:

c
class HUDManager
{
    protected ref array<ref ServerInfoHUD> m_Panels;

    void HUDManager()
    {
        m_Panels = new array<ref ServerInfoHUD>();
    }

    void AddPanel(ServerInfoHUD panel)
    {
        m_Panels.Insert(panel);
    }

    void UpdateAll(float timeslice)
    {
        int count = m_Panels.Count();
        int i = 0;
        while (i < count)
        {
            m_Panels.Get(i).Update(timeslice);
            i++;
        }
    }
};

Draggable HUD Elements ​

Making a widget draggable requires handling mouse events via ScriptedWidgetEventHandler:

c
class DraggableHUD : ScriptedWidgetEventHandler
{
    protected bool m_Dragging;
    protected float m_OffsetX;
    protected float m_OffsetY;
    protected Widget m_DragWidget;

    override bool OnMouseButtonDown(Widget w, int x, int y, int button)
    {
        if (w == m_DragWidget && button == 0)
        {
            m_Dragging = true;
            float wx, wy;
            m_DragWidget.GetScreenPos(wx, wy);
            m_OffsetX = x - wx;
            m_OffsetY = y - wy;
            return true;
        }
        return false;
    }

    override bool OnMouseButtonUp(Widget w, int x, int y, int button)
    {
        if (button == 0)
            m_Dragging = false;
        return false;
    }

    override bool OnUpdate(Widget w, int x, int y, int oldX, int oldY)
    {
        if (m_Dragging && m_DragWidget)
        {
            m_DragWidget.SetPos(x - m_OffsetX, y - m_OffsetY);
            return true;
        }
        return false;
    }
};

Note: for dragging to work, the widget must have SetHandler(this) called on it so the event handler receives events. Also, the cursor must be visible, which limits draggable HUDs to situations where a menu or edit mode is active.

Common Mistakes ​

1. Updating Every Frame Instead of Throttled ​

Wrong:

c
override void OnUpdate(float timeslice)
{
    super.OnUpdate(timeslice);
    m_ServerInfoHUD.RefreshTime();      // Runs 60+ times per second!
    m_ServerInfoHUD.RequestServerInfo(); // Sends 60+ RPCs per second!
}

Right: Use a timer accumulator (as shown in the tutorial) so expensive operations run at most once per second. HUD text that changes every frame (like an FPS counter) is fine to update per-frame, but RPC requests must be throttled.

2. Not Cleaning Up in OnMissionFinish ​

Wrong:

c
modded class MissionGameplay
{
    ref ServerInfoHUD m_HUD;

    override void OnInit()
    {
        super.OnInit();
        m_HUD = new ServerInfoHUD();
        m_HUD.Init();
        // No cleanup anywhere -- widget leaks on disconnect!
    }
};

Right: Always destroy widgets and null references in OnMissionFinish(). The destructor (~ServerInfoHUD) is a safety net, but do not rely on it -- OnMissionFinish is the correct place for explicit cleanup.

3. HUD Behind Other UI Elements ​

Widgets created later render on top of widgets created earlier. If your HUD appears behind vanilla UI, it was created too early. Solutions:

  • Create the HUD later in the initialization sequence (e.g., on the first OnUpdate call rather than in OnInit).
  • Use m_Root.SetSort(100) to force a higher sort order, pushing your widget above others.

4. Requesting Data Too Frequently (RPC Spam) ​

Sending an RPC every frame creates 60+ network packets per second per connected player. On a 60-player server, that is 3,600 packets per second of unnecessary traffic. Always throttle RPC requests. Once per second is reasonable for non-critical info. For data that rarely changes (like server name), you could request it only once at init and cache it.

5. Forgetting the super Call ​

c
// WRONG: breaks vanilla HUD functionality
override void OnInit()
{
    m_HUD = new ServerInfoHUD();
    m_HUD.Init();
    // Missing super.OnInit()! Vanilla HUD will not initialize.
}

Always call super.OnInit() (and super.OnUpdate(), super.OnMissionFinish()) first. Omitting the super call breaks the vanilla implementation and every other mod that hooks the same method.

6. Using Wrong Script Layer ​

If you try to reference MissionGameplay from 4_World, you will get an "Undefined type" error because 5_Mission types are not visible to 4_World. The RPC constants go in 3_Game, the server handler goes in 4_World (modding PlayerBase which lives there), and the HUD class and mission hook go in 5_Mission.

7. Hardcoded Layout Path ​

The layout path in CreateWidgets() is relative to the game's search paths. If your PBO prefix does not match the path string, the layout will not load and CreateWidgets returns NULL. Always check for NULL after CreateWidgets and log an error if it fails.

Next Steps ​

Now that you have a working HUD overlay, consider these progressions:

  1. Save user preferences -- Store whether the HUD is visible in a local JSON file so the toggle state persists across sessions.
  2. Add server-side configuration -- Let server admins enable/disable the HUD or choose which fields to show via a JSON config file.
  3. Build an admin overlay -- Expand the HUD to show admin-only information (server performance, entity count, restart timer) using permission checks.
  4. Create a compass HUD -- Use GetGame().GetCurrentCameraDirection() to calculate heading and display a compass bar at the top of the screen.
  5. Study existing mods -- Look at DayZ Expansion's quest HUD and Colorful UI's overlay system for production-quality HUD implementations.

Best Practices ​

  • Throttle OnUpdate to 1-second intervals minimum. Use a timer accumulator to avoid running expensive operations (RPC requests, text formatting) 60+ times per second. Only per-frame visuals like FPS counters should update every frame.
  • Hide the HUD when inventory or any menu is open. Check GetGame().GetUIManager().GetMenu() on each update and suppress your overlay. Overlapping UI elements confuse players and block interaction.
  • Always clean up widgets in OnMissionFinish. Leaked widget roots persist across server hops, stacking ghost panels that consume memory and eventually cause visual glitches.
  • Use SetSort() to control render order. If your HUD appears behind vanilla elements, call m_Root.SetSort(100) to push it above. Without explicit sort order, creation timing determines layering.
  • Cache server data that rarely changes. The server name does not change during a session. Request it once at init and cache it locally instead of re-requesting it every second.

Theory vs Practice ​

ConceptTheoryReality
OnUpdate(float timeslice)Called once per frame with the frame delta timeOn a 144 FPS client, this fires 144 times per second. Sending an RPC each call creates 144 network packets/second per player. Always accumulate timeslice and act only when the sum exceeds your interval.
CreateWidgets() layout pathLoads the layout from the path you provideThe path is relative to the PBO prefix, not the file system. If your PBO prefix does not match the path string, CreateWidgets silently returns NULL with no error in the log.
WidgetFadeTimerSmoothly animates widget opacityFadeOut hides the widget after the animation completes, but FadeIn does NOT call Show(true) first. You must manually show the widget before calling FadeIn, or nothing appears.
GetUApi().GetInputByName()Returns the input action for your custom keybindIf inputs.xml is not referenced in config.cpp under class inputs, the action name is unknown and GetInputByName returns null, causing a crash on .LocalPress().

What You Learned ​

In this tutorial you learned:

  • How to create a HUD layout with anchored, semi-transparent panels
  • How to build a controller class that throttles updates to a fixed interval
  • How to hook into MissionGameplay for HUD lifecycle management (init, update, cleanup)
  • How to request server data via RPC and display it on the client
  • How to register a custom keybind via inputs.xml and toggle HUD visibility with fade animations

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