Development/es

Este artículo pretende introducirte en el desarollo de DDNet, Al tratarse de un juego de código abierto, depende de las personas que contribuyen a él en su tiempo libre.

Tu entorno de desarrollo

Es extremadamente recomendable configurar algún entorno de Linux para empezar a programar en DDNet por las siguientes razones (a partir de ahora):

• La mayoría de los colaboradores de DDNet utilizan Linux para contribuir.
• Gestión de paquetes más simple, puedes instalar fácilmente todas las librerías necesarias y empezar a contribuir.
• Este artículo aún no tiene versión para Windows y se centra en Linux.

Primero que todo, DDNet está codificado usando el lenguaje de programación C++, necesitarás estar bastante familiarizado con él, pero también puedes saber lo básico y aprender más con él.

Algunos recursos útiles para aprender C++:

• learncpp.com
• cppreference.com
• El motor de búsqueda que prefiera

El código fuente de DDNet se gestiona mediante Git, un sistema de control de versiones, una herramienta esencial para colaborar con múltiples desarrolladores.

Si aún no tiene git en su distribución Linux, asegúrese de instalarlo, por ejemplo, en la mayoría de las distribuciones basadas en debian/ubuntu se instala con el siguiente comando en la terminal: sudo apt install git.

Obtener el código fuente

El código fuente se encuentra en Github, puedes obtener el código fuente clonándolo sin necesidad de una cuenta, pero si alguna vez quieres poner tus cambios en el código fuente oficial necesitarás una.

Si no estás familiarizado con git/github puedes aprender lo básico aquí: Hola Mundo - Github

Instalación de dependencias

Si utiliza Linux, puede instalar todas las dependencias necesarias leyendo el archivo README en la página de DDNet en github: https://github.com/ddnet/ddnet#dependencies-on-linux--macos

Para Arch Linux:

sudo pacman -S --needed base-devel cmake curl freetype2 git glew gmock libnotify opusfile python sdl2 sqlite wavpack

Compilación de DDNet

Usamos CMake para controlar el proceso de compilación, si tienes todas las dependencias instaladas, es tan fácil como seguir estos comandos (asegúrate de estar en la carpeta de DDNet):

mkdir build
cd build
cmake ..
make -j$(nproc)

Información general

Here are some general bits of information:

• Currently, the source code is compiled with the C++17 standard, but you will see that many parts of the code are more C-like since only mostly new code uses C++17 stuff.
• std::string is rarely used, char arrays plus using system.h methods for handling them are the norm.
• Most I/O code, formatting and printing is done using system.h provided methods.

The source code layout

Now that you can build DDNet you can begin editing it.

The src/base directory

Since DDNet is a cross-platform game, an abstraction layer over that is needed to make development easier, this directory contains many useful functions to handle that.

The src/engine directory

Here lies the game engine, it handles most stuff that is not gameplay related, such as graphics, sound, network, etc.

The src/game directory

All gameplay related code is here, separated into client and server.

Server side

This game uses its own Entity Component System, the main class to which all other entities derive from is CEntity located in src/game/server/entity.h.

These entities are managed by the game world located here src/game/server/gameworld.h

Some important entities are:

• CCharacter: Represents a tee that is alive, it is instantiated when a tee spawns and deleted when it dies. For information about the player kept between deaths, see CPlayer.

Client side

The client side is made up of components, these are classes that inherit CComponent: These components can implement the virtual methods such as OnInit, OnMessage, etc. to provide their functionality.

Networking

The network protocol is mostly generated by python scripts that output C++ code, for example, datasrc/network.py defines all network packets.

Code conventions

The ongoing discussion on code conventions is located here: ddnet#2945

Currently, the following applies:

Indentation style

Allman style is used.

This style puts the brace associated with a control statement on the next line, indented to the same level as the control statement. Statements within the braces are indented to the next level.

while(x == y)
{
    Something();
    SomethingElse();
}
</div>

<div lang="en" dir="ltr" class="mw-content-ltr">
Finalthing();

Classes and Structs

Must be prefixed by C (for legacy reasons this is ignored for structs in some places, such as in graphics code) or I for interfaces.

Example:

class CCharacter : public CEntity
{
    // ...
}

Enums and constants

Should be screaming snake case, for example: MAX_PLAYERS

enum
{
	FAKETUNE_FREEZE = 1,
	FAKETUNE_SOLO = 2,
	FAKETUNE_NOJUMP = 4,
	FAKETUNE_NOCOLL = 8,
	FAKETUNE_NOHOOK = 16,
	FAKETUNE_JETPACK = 32,
	FAKETUNE_NOHAMMER = 64,
};

Variable naming

• The names of variables contain 3 parts: qualifier, prefix and name.
• Variable names should start with uppercase unless they are 1 char long without any prefix or qualifier, for example: i, x, y.
• Variables can have more than 1 qualifier (or zero) and more than 1 prefix (or zero).

These are laid out like this: [qualifiers]_[prefixes][Name]

Qualifiers

• m for member variables: m_MyVariable.
• s for static variables: s_MyStaticVariable.
• g for global variables with external linkage: gs_MyGlobalStaticVar.

Prefixes

• p for pointers: pMyPointer, m_pCharacter, ppMyPointerToPointer.
• a for arrays: aMyArray, aBuf.
• fn for functions: pfnMyCallback, m_papfnMyPointerToArrayOfCallbacks.

Common snippets

Here is a list of code that you may frequently see across the codebase:

Formatting text

char aBuf[128];
str_format(aBuf, sizeof(aBuf), "number: %d", 2);

Iterating over all players

for(int i = 0; i < MAX_CLIENTS; i++)
{
    // Server-side
    CPlayer *pPlayer = GameServer()->m_apPlayers[i];
}

Printing to the game console

Console()->Print(IConsole::OUTPUT_LEVEL_STANDARD, "wikiprint", "Hello from the ddnet wiki!");

Debug printing

int i = 2;
dbg_msg("wikiprint", "Hello from the ddnet wiki: %d", i);

External resources

• An intro to the DDraceNetwork game source code by Ryozuki
• Code conventions in DDraceNetwork by Ryozuki
• Implementing a chat command in DDraceNetwork by Ryozuki
• Auto generated docs
• Technical documentation of Teeworlds file formats and network protocol
• The Anatomy of a One Tick Unfreeze
• Teeworlds programming YouTube tutorial by ChillerDragon