Plants vs. Zombies Online Battle

Introduction

This project adds the multiplayer battle to Plants vs. Zombies via reverse engineering, inline hook and dynamic-link library injection. Two online players can defend and attack as Plant and Zombie respectively.

Getting Started

Prerequisites

• Install Visual Studio 2022.
• Install CMake.
• Set the PATH environment variables.

Building

Set the location to the project folder and run:

mkdir -p build
cd build
cmake .. -G "Visual Studio 17 2022" -A Win32
cmake --build .

Two dynamic-link libraries plant.dll and zombie.dll will be generated in build/bin folder. Copy them to the game root folder.

IPv6

The default IP version is IPv4. Enable the following statement in libs/game/CMakeLists.txt if you want to build IPv6 libraries.

target_compile_definitions(game PRIVATE INET6=1)

Usage

The project only works with Plants vs. Zombies 1.0.0.1051 CHINESE version, provided in game folder.

The MD5 of PlantsVsZombies.exe is 37B729B4056131722A556E646AC915E9.

In order to activate online functions, plant.dll and zombie.dll must be injected into the game when it starts. You can directly use this simple injection tool: Dll-Injector.

Playing as Plant

If a player plays as the plant, the game will launch as a server.

Dll-Injector -f PlantsVsZombies.exe plant.dll

Or use Start-OnlineGame.ps1 directly. It needs to be copied to the game root folder.

Start-OnlineGame.ps1 -Role Plant

Start I, Zombie Endless level, the game will pause and wait for a client to connect.

Playing as Zombie

If a player plays as the zombie, the game will launch as a client.

Dll-Injector -f PlantsVsZombies.exe zombie.dll

Or use Start-OnlineGame.ps1.

Start-OnlineGame.ps1 -Role Zombie

Start I, Zombie Endless level, the game will try to connect to the server.

I, Zombie Endless

If the modification has been loaded successfully, I, Zombie Endless level will be converted into an online level. If your current progress does not have this level, you can copy game/userdata to C:\ProgramData\PopCap Games\PlantsVsZombies\userdata. Remember to back up your own save-files before copying.

In the Chinese version of the game, you can start this level as follows:

1. Select "解谜模式", which means "Puzzle" in English.

   

2. Select "我是僵尸无尽版", the final level. It is "I, Zombie Endless" in English.

   

3. The game will display a dialog box shown as below. Select "继续", the left button, meaning "Continue" in English.

   

   Before starting an online battle, the progress of this level must be empty. Otherwise the battlefields of two online players will be different. If that happens, you need to restart the game without the modification, enter this level again but select "新游戏", the right button, to reset the progress. It means "New Game".

Configurations

Copy online_config.ini to the game root folder. You can set the server's IP address and port number in it.

[Network]
ServerIP=127.0.0.1
Port=10000

Documents

The code comment style follows the Doxygen specification.

docs/Key Data and Functions.md describes key data and functions obtained by reverse engineering.

Class Diagram

classDiagram

namespace state {

    class Role {
        <<enumeration>>
        Plante
        Zombie
    }

    class Config {
        vector~int~ zombies
        vector~int~ plants
        string server_ip
        int port
    }

    class State
}

State --> Role
State --> Config
State --> TcpSocket

namespace network {

    class IpAddr {
        <<interface>>
        Version() int
    }

    class Ipv4Addr
    class Ipv6Addr

    class Socket {
        SetAddr(IpAddr)
        Bind()
        Close()
    }

    class TcpSocket {
        <<>>
        Connect(IpAddr)
        Send(data) size
        Recv(buffer) size
    }

    class Listener {
        Bind(IpAddr)
        Listen()
        Accept() TcpSocket
        Close()
    }

    class Packet {
        Recv(TcpSocket)$ Packet
        Send(TcpSocket)
        Write(data) size
        Read() data
    }
}

IpAddr <|.. Ipv4Addr
IpAddr <|.. Ipv6Addr
Socket --> IpAddr
Socket <|-- TcpSocket
Listener --> TcpSocket
Packet ..> TcpSocket

class Mod {
    <<interface>>
    Enable()
    Disable()
}

class ModLoader {
    Add(Mod)
    Load()
}

ModLoader o-- Mod

class RemoveDefaultPlants
Mod <|.. RemoveDefaultPlants

class SetSunAmount
Mod <|.. SetSunAmount

class Hook {
    <<interface>>
    #From() address
    #To() address
    #JumpRet() optional~address~
}

Mod <|-- Hook

class BeforeLoadLevel
Hook <|.. BeforeLoadLevel
BeforeLoadLevel ..> CreateZombie
BeforeLoadLevel ..> CreatePlant
BeforeLoadLevel ..> LevelEnd
BeforeLoadLevel ..> Listener
BeforeLoadLevel ..> State

class AfterLoadLevel
Hook <|.. AfterLoadLevel
AfterLoadLevel ..> RemoveDefaultPlants
AfterLoadLevel ..> InitSlots

class InitSlots
Hook <|.. InitSlots
InitSlots ..> State

class LevelEnd
Hook <|.. LevelEnd
LevelEnd ..> State
LevelEnd ..> Packet

class CreateZombie
Hook <|.. CreateZombie
CreateZombie ..> State
CreateZombie ..> Packet

class CreatePlant
Hook <|.. CreatePlant
CreatePlant ..> State
CreatePlant ..> Packet

class Startup {
    Run()
    Stop()
}

Startup --> ModLoader
Startup --> State

Issues & Bugs

• The game sometimes crashes when creating zombies.
• If the progress of I, Zombie Endless level is not empty, two players will have different battlefields.
• In order to simplify the code, the running menu and automatic pause are disabled.

License

Distributed under the MIT License. See LICENSE for more information.