Creating a plugin with RedLib

This guide will show you how you can write a plugin with beautiful code thanks to RedLib and RED4ext.SDK. If you haven't, you should learn the fundamentals of writing a plugin (see Creating a Plugin).

Requirements

You must install RED4ext.SDK in your project like any other plugin (see Creating a plugin). You need to install RedLib. See the README to configure your CMake project.

Setup plugin to register types

Now you can change the entry-point of your plugin like this:

/// File: src\\main.cpp

#include <RED4ext/RED4ext.hpp>
// You must include RedLib. Note that it introduces an alias
// such as namespace RED4ext can be replaced by Red.
#include <RedLib.hpp>

RED4EXT_C_EXPORT bool RED4EXT_CALL Main(RED4ext::PluginHandle aHandle,
                                        RED4ext::EMainReason aReason,
                                        const RED4ext::Sdk* aSdk) {
  switch (aReason)  {
  case RED4ext::EMainReason::Load: {
    // It will automatically register types declared below.
    Red::TypeInfoRegistrar::RegisterDiscovered();
    break;
  }
  case RED4ext::EMainReason::Unload: {
    break;
  }
  }
  return true;
}

// ...

Declare new classes

We are going to create a zoo, and name our mod... Zoo. Now lets create a generic Animal class:

/// File: src\\Animal.hpp

#include <RED4ext/Scripting/Natives/Generated/Vector4.hpp>
#include <RedLib.hpp>

class Animal : public Red::IScriptable {
public:
  //Animal() = default;

  virtual bool CanFly() const {
    return false;
  }
  virtual bool CanWalk() const {
    return false;
  }

  virtual bool is_carnivore() const {
    return false;
  }
  virtual bool is_herbivore() const {
    return false;
  }

  Red::Vector4 position{};

  RTTI_IMPL_TYPEINFO(Animal);
  RTTI_IMPL_ALLOCATOR();
}

RTTI_DEFINE_CLASS(Animal, {
  // You only need to add an alias when declaring scripts 
  // with 'module' and 'import' keywords.
  RTTI_ALIAS("Zoo.Animal");

  RTTI_ABSTRACT();

  RTTI_METHOD(CanFly);
  RTTI_METHOD(CanWalk);

  // You can use another name to declare instead.
  RTTI_METHOD(is_carnivore, "IsCarnivore");
  RTTI_METHOD(is_herbivore, "IsHerbivore");
  
  RTTI_GETTER(position);
});

Now lets add a Wolf to our zoo:

/// File: src\\Wolf.hpp

#include <RedLib.hpp>

#include "Animal.hpp"

class Wolf : public Animal {
public:
  //Wolf() = default;

  bool CanWalk() const override {
    return true;
  }

  bool IsCarnivore() const override {
    return true;
  }

  bool CanHunt() const {
    return true;
  }

  RTTI_IMPL_TYPEINFO(Wolf);
  RTTI_IMPL_ALLOCATOR();
};

RTTI_DEFINE_CLASS(Wolf, {
  RTTI_ALIAS("Zoo.Wolf");

  RTTI_PARENT(Animal);

  // Redeclare methods you override.
  RTTI_METHOD(CanWalk);
  RTTI_METHOD(is_carnivore, "IsCarnivore");

  RTTI_METHOD(CanHunt);
});

If you tried to declare a class with only RED4ext.SDK so far, it sure looks better now with RedLib! Now compile your project and install your plugin in the game's directory:

<Cyberpunk 2077>\red4ext\plugins\Zoo\Zoo.dll

We also need to declare native types so we can use them in scripts:

/// File: scripts\\Zoo.reds

// Again, declaring native types within a module
// is not required.
module Zoo

public abstract native class Animal extends IScriptable {
  public native func CanFly() -> Bool;
  public native func CanWalk()-> Bool;

  public native func IsCarnivore() -> Bool;
  public native func IsHerbivore() -> Bool;

  public native func GetPosition() -> Vector4;
}

public native class Wolf extends Animal {
  // You don't need to redeclare methods of the parent,
  // even when you override them.

  // But you have to declare new methods.
  public native func CanHunt() -> Bool;
}

Lets create our zoo somewhere when the game starts:

/// File: scripts\\ZooTest.reds

import Zoo.*

public class ZooSystem extends ScriptableSystem {
  private let m_animals: array<ref<Animal>>;

  private func OnAttach() {
    // Create a pack of wolves.
    ArrayPush(this.m_animals, new Wolf());
    ArrayPush(this.m_animals, new Wolf());
    ArrayPush(this.m_animals, new Wolf());
    ArrayPush(this.m_animals, new Wolf());

    for animal in this.m_animals {
      LogChannel(n"Info", s"Class name: s\(animal.GetClassName())");
      LogChannel(n"Info", "");
      LogChannel(n"Info", s"Can fly? s\(animal.CanFly())");
      LogChannel(n"Info", s"Can walk? s\(animal.CanWalk())");
      LogChannel(n"Info", s"Is carnivore? s\(animal.IsCarnivore())");
      LogChannel(n"Info", s"Is herbivore? s\(animal.IsHerbivore())");
      let wolf = animal as Wolf;

      LogChannel(n"Info", "");
      LogChannel(n"Info", s"Can hunt? \(wolf.CanHunt())");
      LogChannel(n"Info", "");
    }
  }

  private func OnDetach() {
    ArrayClear(this.m_animals);
  }

}

Install scripts in your game's directory:

<Cyberpunk 2077>\r6\scripts\Zoo\Zoo.reds

<Cyberpunk 2077>\r6\scripts\ZooTest.reds

Run the game, you should see some outputs in the Game Log when using CET.

Conclusion

This is a simple introduction to RedLib and how it can make your life easier when writing plugin with RED4ext.SDK. You should definitively go to the GitHub repository and read through the entire README to learn about all the features it provides.

Happy coding!