Hazel game engine (122) C# separates game and core library code

If there are errors in the code, terminology, etc. in the text, please correct me

foreword

• of this program

  Use the C# game code as a new workspace project and reference the C# core library project

  • 1 C# core library project

  • 1 C# script project

    The script inside calls the function of the C# core library to realize the script function

  Like Unity development, Unity has its own set of dll, we need to write script using UnityEngine;, call the Unity library dll to achieve the corresponding effect

• How to achieve

  Use premake5 to make quickly

• implementation details

  • When the C# game code and the core library code are separated, the C++ loading dll changes from one to two

  • Get the Mono class of the C# dll

    It should be distinguished that it is the Mono class that obtains the C# core library assembly

    Or get the Mono class of the C# application set

Project structure related

new workspace new script project

• new workspace file path

  Under the GameEngine-Editor editor project

  

• Premake of the new Sandbox script project

  local UnifyRootDir = "../../../.."
  
  workspace "Sandbox"
  	architecture "x86_64"
  	startproject "Sandbox"
  	configurations{
        
        
  		"Debug",
  		"Release",
  		"Dist"
  	}
  	flags{
        
        
  		"MultiProcessorCompile"
  	}
  
  outputdir = "%{cfg.buildcfg}-%{cfg.system}-%{cfg.architecture}"
  
  project "Sandbox"
  	kind "SharedLib"
  	language "C#"
  	dotnetframework "4.7.2"
  
  	targetdir ("Binaries")
  	objdir ("Intermediates")
  
  	files{
        
        
  		"Source/**.cs",
  		"Properies/**.cs"
  	}
  	links{
        
        
  		"GameEngine-ScriptCore"
  	}
  	filter "configurations:Debug"
  		optimize "Off"
  		symbols "Default"
  
  	filter "configurations:Release"
  		optimize "On"
  		symbols "Default"
  
  	filter "configurations:Dist"
  		optimize "Full"
  		symbols "Off"
  
  group "Unify"
  	include (UnifyRootDir .. "/GameEngine-ScriptCore")
  group ""
  

New Sandbox script project structure

• The Sandbox project references the GameEngine-ScriptCore project
• The Sandbox project contains the Player.cs game logic script code moved from the GameEngine-ScriptCore project

New Sanbox script project generates dll

• build directory set by premake

  targetdir ("Binaries")
  objdir ("Intermediates")
  

• Since the Sandbox project references the GameEngine-ScriptCore project

  So the generation will not only generate Sandbox.dll but also GameEngine-ScriptCore.dll

project code changes

The changes made to the project code are to load two dlls and reflect different classes according to different dlls

ScriptEngine.h

//ScriptClass(const std::string& classNamespace, const std::string& className);
ScriptClass(const std::string& classNamespace, const std::string& className, bool isCore = false);
static void LoadAppAssembly(const std::filesystem::path& filepath);
//static void LoadAssemblyClasses(MonoAssembly* assembly);
static void LoadAssemblyClasses();

ScriptEngine.cpp

struct ScriptEngineData {
    
    
    MonoAssembly* CoreAssembly = nullptr;
    MonoImage* CoreAssemblyImage = nullptr;
	// 新增，因加载脚本dll，需保存这两个
    MonoAssembly* AppAssembly = nullptr;
    MonoImage* AppAssemblyImage = nullptr;
};
LoadAssembly("Resources/Scripts/Hazel-ScriptCore.dll");
LoadAppAssembly("SandboxProject/Assets/Scripts/Binaries/Sandbox.dll");
s_Data->EntityClass = ScriptClass("Hazel", "Entity", true);

void ScriptEngine::LoadAssemblyClasses()
{
    
    
    // Entity类在核心库
    MonoClass* entityClass = mono_class_from_name(s_Data->CoreAssemblyImage, "Hazel", "Entity");
    // 从游戏逻辑脚本库里加载脚本类
    const char* nameSpace = mono_metadata_string_heap(s_Data->AppAssemblyImage, cols[MONO_TYPEDEF_NAMESPACE]);
    const char* name = mono_metadata_string_heap(s_Data->AppAssemblyImage, cols[MONO_TYPEDEF_NAME]);
	MonoClass* monoClass = mono_class_from_name(s_Data->AppAssemblyImage, nameSpace, name);
}
void ScriptEngine::LoadAppAssembly(const std::filesystem::path& filepath)
{
    
    
    // Move this maybe
    s_Data->AppAssembly = Utils::LoadMonoAssembly(filepath);
    auto assemb = s_Data->AppAssembly;
    s_Data->AppAssemblyImage = mono_assembly_get_image(s_Data->AppAssembly);
    auto assembi = s_Data->AppAssemblyImage;
    // Utils::PrintAssemblyTypes(s_Data->AppAssembly);
}
ScriptClass::ScriptClass(const std::string& classNamespace, const std::string& className, bool isCore)
    : m_ClassNamespace(classNamespace), m_ClassName(className)
{
    
    
    /*
    得到C# dll的Mono类
    应该**区分**是获取C#核心库程序集的 Mono类
    还是获取C#应用程序集的 Mono类
    */
   m_MonoClass = mono_class_from_name(s_Data->CoreAssemblyImage, classNamespace.c_str(), className.c_str());
   m_MonoClass = mono_class_from_name(isCore ? s_Data->CoreAssemblyImage : s_Data->AppAssemblyImage, classNamespace.c_str(), className.c_str());
}

Encountered bugs

• GameEngine-ScriptCore.dll could not be loaded

  GameEngine-ScriptCore.dll is generated in the GameEngine-Editor\SandboxProject\Assets\Scripts\Binaries folder

  Instead of in the GameEngine-Editor\Resources\Scripts folder

  • reason

    The new Sandbox project contains a reference to the GameEngine-ScriptCore project

    The generated file path written by Sandbox's premake is

    targetdir ("Binaries")
    objdir ("Intermediates")
    

    And the premake of GameEngine-ScriptCore writes

    targetdir ("%{wks.location}/GameEngine-Editor/Resources/Scripts")
    objdir ("%{wks.location}/GameEngine-Editor/Resources/Scripts/Intermediates")
    

    Pay attention to the code %{wks.location}, it gets the location of **.sln**

    • Originally the GameEngineLightWeight workspace contained it

      %{wks.location} = GameEngineLightWeight

      So the generated directory is:

      GameEngineLightWeight\GameEngine-Editor\Resources\Scripts

    • But the new Sandbox also has its own new workspace , and also contains this GameEngine-ScriptCore project

      %{wks.location} = GameEngineLightWeight\GameEngine-Editor\SandboxProject\Assets\Scripts

      So this build directory becomes:

      GameEngineLightWeight\GameEngine-Editor\SandboxProject\Assets\Scripts\GameEngine-Editor\Resources\Scripts

  • The path is generated as follows

    

    The generated path is different from the path where the code loads the dll, so an error will be reported

  • How to solve

    Modify the build path in the premake of the GameEngine-ScriptCore project

    -- 获取的是.sln所在的位置
    --targetdir ("%{wks.location}/GameEngine-Editor/Resources/Scripts")
    --objdir ("%{wks.location}/GameEngine-Editor/Resources/Scripts/Intermediates")
    targetdir ("../GameEngine-Editor/Resources/Scripts")
    objdir ("../GameEngine-Editor/Resources/Scripts/Intermediates")
    

    %{wks.location} replaced by .../

  • regenerate path