AZ::Console

The AZ::Console class provides a set of macros for defining variables and mapping functions that you can use to interact with in-game variables and processes. Use the macros defined in this class to set the console variables (cvars) and functors (cfuncs) for your game, and then access them through the O3DE console.

AZ::Console is defined in the following header: %INSTALL-ROOT%\dev\Code\Framework\AzCore\AzCore\Console\IConsole.h

AZ::Console features:

  • Basic access protections and anti-cheat mechanisms for locking down cvars and cfuncs in release builds.
  • Default support for several C++ types, including bool (Boolean), stdint (all types), floats, doubles, vectors and quaternions, and enums (enumerations).
  • Flexible and expandable type support. You can add support for new cvar types without altering the console code directly.

The AZ::Console

Topics

Console variables (cvars)

Declare a cvar using one of two macros from IConsole.h:

AZ_CVAR(_TYPE, _NAME, _INIT, _CALLBACK, _FLAGS, _DESC) //Standard cvar macro, provides no external linkage.
AZ_CVAR_EXTERNABLE(_TYPE, _NAME, _INIT, _CALLBACK, _FLAGS, _DESC) //Cvar macro that creates a console variable with external linkage.

Parameters:

  • _TYPE: The base type of the cvar.

  • _NAME: The name of the cvar.

  • _INIT: The initial value to assign to the cvar.

  • _CALLBACK: An optional callback function invoked when a cvar changes value.

    Note:
    These macros do not guarantee that this callback will be run on a specific thread. The implementor of the callback handler is responsible for ensuring thread safety.
  • _FLAGS: One or more AZ::Console::FunctorFlags that are used to mutate behavior. Use the logical AND (&&) and OR (||) operators to combine flags. If you do not have any flags to set, use FunctorFlags::None.

  • _DESC: String that provides a short description of the cvar for display.

To declare a new cvar in your code, include the IConsole.h header. Then use one of the cvar macros (such as AZ_CVAR) to declare your new console variable in your own code (.cpp) files.

Note:
AZ_CVAR and AZ_CVAR_EXTERNABLE variables can be declared only in C++ code (.cpp) files. AZ_CVAR_EXTERNED variables, however, can be declared in either C++ code (.cpp) or header (.h) files.

Here are some examples.

AZ_CVAR(int32_t, cl_GameServiceRefreshTimeMs, 1000, nullptr, FunctorFlags::None, "Controls the auto-refresh delay for all gameService data, time in milliseconds");
AZ_CVAR(bool,    cl_QuitOnHubDisconnect,     false, nullptr, FunctorFlags::None, "If enabled, the client executable will terminate on disconnect");
void OnConsoleResUpdate(const int32_t& a_NewWidth)
{
    // Run update for new value
}

AZ_CVAR(int32_t, sv_ConsoleWidth, 160, OnConsoleResUpdate, FunctorFlags::ReadOnly, "The width of the server console window");
AZ_CVAR_EXTERNABLE(uint16_t, net_ServerRateMs, 33, nullptr, FunctorFlags::ReadOnly, "Server tick rate to use for network relevent simulations");

Optionally, use the following name prefixes to help organize groups of cvars:

  • sv_: For server only cvars
  • cl_: For client only cvars
  • bg_ : “Both games” for common cvars (client and server)

These prefixes are useful to quickly limit the scope of autocomplete, and to see groups of associated cvars in the console. You can use your own prefixes as well.

To make an existing console variable external (extern), use the AZ_CVAR_EXTERNED macro:

AZ_CVAR_EXTERNED(_TYPE, _NAME)

Make sure that the **_TYPE **and _NAME parameters match those of the previously defined cvar.

Console functors (cfuncs)

Console functions allow you to register a command with the console that’s not associated with a specific type or value. In O3DE, they’re purely a mechanism to allow a method to be invoked directly from the O3DE in-game console.

There are two types of cfuncs: one to invoke class member methods (AZ_CONSOLEFUNC), and one to invoke static methods (AZ_CONSOLEFREEFUNC).

To declare a class member method cfunc, use the AZ_CFUNC macro from IConsole.h:

AZ_CONSOLEFUNC(_CLASS, _FUNCTION, _INSTANCE, _FLAGS, _DESC)

Parameters:

  • _CLASS: The class that contains the method (function) for invocation.

  • _FUNCTION: The method to invoke as a callback.

    Note:
    These macros do not guarantee that this callback will be run on a specific thread. The implementor of the callback handler is responsible for ensuring thread safety.
  • _INSTANCE: The instance of the class on which this method gets invoked (usually set to this for the current instance).

  • _FLAGS: One or more AZ::Console::FunctorFlags that are used to mutate behavior. Use the logical AND (&&) and OR (||) operators to combine flags. If you do not have any flags to set, use FunctorFlags::None.

  • _DESC: String that provides a short description of the cfunc for display.

Some examples of cfunc declarations:

class Example
{
public:
    Example() { AZ_CONSOLEFUNC(Example, Method, this, FunctorFlags::DontReplicate, "Executes the Method method on this Example instance, invoke in the console using Example.Method"); }
    void Method(const StringSet&) {}
};

To declare a cfunc for a static method (or other non-member function), use the AZ_CONSOLEFREEFUNC macro:

AZ_CONSOLEFREEFUNC(_FUNCTION, _FLAGS, _DESC)

Parameters:

  • _FUNCTION: The static method to invoke as a callback.

    Note:
    These macros do not guarantee that this callback will be run on a specific thread. The implementor of the callback handler is responsible for ensuring thread safety.
  • _FLAGS: One or more AZ::Console::FunctorFlags that are used to mutate behavior. Use the logical AND (&&) and OR (||) operators to combine flags. If you do not have any flags to set, use FunctorFlags::None.

  • _DESC: String that provides a short description of the cfunc for display.

Example:

void ForceEnableMetrics(const StringSet&) {}
    AZ_CONSOLEFREEFREEFUNC(ForceEnableMetrics, FunctorFlags::Null, "If called, force enable metrics");

Optional flags

AZ::Console provides a set of flags that can be passed to cvar and cfunc declarations and indicate how they should be handled:

enum class FunctorFlags
{
    Null           = 0        // Empty flags
,   DontReplicate  = (1 << 0) // Should not be replicated (CURRENTLY UNUSED)
,   ServerOnly     = (1 << 1) // Should never replicate to clients (CURRENTLY UNUSED)
,   ReadOnly       = (1 << 2) // Should not be invoked at runtime
,   IsCheat        = (1 << 4) // Should not be shown in the console for autocomplete
,   IsDeprecated   = (1 << 5) // Command is deprecated, show a warning when invoked
,   NeedsReload    = (1 << 6) // Level should be reloaded after executing this command
,   AllowClientSet = (1 << 7) // Allow clients to modify this cvar even in release (this alters the cvar for all connected servers and clients, be VERY careful enabling this flag) (CURRENTLY UNUSED)
};

Adding support for new console variable types

To add support for a new cvar type, override the two template methods that convert the custom type to a space-delimited string from a vector of space-delimited string inputs.

As an example, an override that converts AZ::Vector3 to a string and back to a value is declared like this:

namespace AZ
{
    // CVar compatibility
    namespace ConsoleTypeHelpers
    {
        template <>
        AZStd::string ValueToString<AZ::Vector3>(const AZ::Vector3& a_Value);

        template <>
        bool StringSetToValue<AZ::Vector3>(AZ::Vector3& a_OutValue, const StringSet& a_Arguments);
    }
}

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