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In this tutorial you will learn how to modify existing and create new CVars (Console Variables).

These  variables can be used to control many configurable behaviors in CRYENGINE, and can also be used in your game.

This tutorial is targeted at programmers, most of the contents deals with code.

Creating New CVars

In your code IDE, open up the Code\GameSDK\GameDll\GameCVars.h file, this file declares all the game-specific CVars.

Locate the SCVars struct, and inside the struct declare a new variable:

struct SCVars
	int g_tutorialVar; //add this line
	//... pre-existing code ...
 You can also add a variable of float type, if you need to store fractional numbers

The variable you added will be used to store the current value of the variable.

Now, the CVar needs to be registered in the engine, so it's value can be changed through the console

Open up the Code\GameSDK\GameDll\GameCVars.cpp file, and locate the InitCVars function:

void SCVars::InitCVars(IConsole *pConsole)
	m_releaseConstants.Init( pConsole );
	REGISTER_CVAR(g_tutorialVar, 42, VF_NULL, "This CVar was added using the tutorial on CVars"); //add this line
    //... pre-existing code ...

In the above example, we specify the default value 42 for the variable, and we add some help text that can be shown to other users.

You can initialize the variable to any value that is valid for the variable's type as declared in the header file.

Don't forget to also un-register the variable when your game is unloaded, in the same .cpp file locate the ReleaseCVars function:

void SCVars::ReleaseCVars()
	IConsole* pConsole = gEnv->pConsole;
	pConsole->UnregisterVariable("g_tutorialVar", true); //add this line
	//... pre-existing code ...

After you finish making code changes, make sure to compile your changes!

Using the CVar

You can now write some code that uses the value of the CVar.

In your game-code you can now access the value through the g_pGameCVars pointer

int myTutorialVar = g_pGameCVars->g_tutorialVar;

Ofcourse, since the variable is now a CVar, you can also bring up the console and access the value there.

Open up the console and type the following to set the value of the variable to 1337:

g_tutorialVar = 1337

It's also possible to change the CVar value from one of the .cfg files to change the default value.

Whenever the value of a CVar is assigned to, the previous value is discarded. Therefore, the last assignment is the one that will be visible.

Therefore, it's important to know the order of initialization for a CVar. From first to last, the order is:

  • The value specified in the GameCVars.cpp file when REGISTER_CVAR is used.
  • The value specified in system.cfg.
  • The value specified in the user's user.cfg.
  • Any value assigned at game runtime.

To change the default value of an existing CVar without having to compile, you can add a line to system.cfg to override the default.