Implicit Resource management Design–Idea

An idea came into my mind today. Why not just make an implicit(automatic) resource management system instead of having some kind of an external resource management system.

Ever since the way I did it was having an external resource manager that I would then use to create the resource I want. Take a look at this sample code below.

Code Snippet 1
  1. void FunkyFunkFunk( void )
  2. {
  3.     Texture *pTexture = TextureManager::GetInstance()->CreateTexture( … );
  4.     
  5.     // Use texture
  6.     pTexture->DoSomething();
  7.     pTexture->DoMoreStuff();
  8.     pTexture->Render();
  9.  
  10.     // We're done with the texture. Remove texture from the manager
  11.     TextureManager::GetInstance()->DeleteTexture( pTexture );
  12. }

As you can see, we create a texture through a texture resource manager called TextureManager and once we’re done with the texture we go through the TextureManager again to remove that created resource.  It’s not really much of a big deal but what if we could just hide the resource management code stuff yet still having all the benefits and convenience of managing your resources? That’s where I thought and said, “Why not just place the manager inside the resource class instead and handle the resource management creation and deletion through the constructor and destructor of the resource respectively?”. hmmm….

 

- MrCodeSushi

A Simple Data Creation Framework

First of all, I wasn’t really sure if I wanted to write this post or not. The data creation framework I made is mostly hacked without proper/formal scripting architectural design. But if this article could help anyone out there in some ways in their programming tasks, even just a little bit, then this blog wouldn’t be a waste. With this in mind, this article will be very brief with very little explanation for its implementation.

This data creation framework I will present enables a data driven architectural design to deliver game data/assets to your game. Since this is a data creation framework, its main purpose is only to bring data; nothing more, nothing less. That means that although the script looks like a full blown scripting language, it is not. This is not like LUA or any other scripting languages that you can define procedural-scripting or gameplay code. This framework simply defines a set of data with an assigned values for the framework to easily read in the data.

If you take a look at the class definition[1], you’ll see lots of containers supporting each data type that the framework supports. Let’s say for example you have a sample script code that looks something like in Code listing 1.

Code Listing 1
  1.     
  2.     Vector3 vec3 = ( 1.0, 3.0, 2.578 );                            // 3D Vectors
  3.     

Code Listing 1: An example of declaring a Vector3 data with a defined value of (1.0, 3.0, 2.578)

vec3, as Vector3 as its data type, will be stored in the Vector3Array container.

So this framework is very simple and straightforward. It doesn’t do anything else other than declare data and this will do fine for the system I’m currently working towards on. The main methods that does the main string parsing and reading are in the GetLine, LoadFromFile, ReadSection, and ReadValue methods.

Here’s the implementation for the framework[1][2]. And a demo script on what the framework can do(Code Listing 2).

Code Listing 2
  1. // This is a sample script used to test Pulse Engine's PulseScript system.
  2. // Below shows some of the features already available.
  3.  
  4. // A comment. An empty space follows below.
  5.  
  6. /*                        MULTI-LINE COMMENT
  7.     This is a multi-line comment. Multi-line comments
  8.     can span multiple lines and PulseScript will strip
  9.     it all out until it hits the closing mult-line comment character.
  10. */
  11.  
  12. // Another comment
  13.  
  14. Section pass // Comment in the same line as the code.
  15. {
  16.  
  17.     String string = "PulseScript can take in strings!!!!";
  18.  
  19.     String multiLineSting = "PulseScript can also take in multi-line strings!!!!\\par                                 This is the second line of a multi-line string.\\par                                 Third line of the multi-line string. Another string in the third line. \\par                                 Fourth line of the multi-string. This is the end of a multi-line string.  ";
  20.     
  21.     // Supports boolean values
  22.     Bool bool1 = true;
  23.     
  24.     // Supports scalar types (i.e. int and float)
  25.     Float f = 3.987654321;
  26.     Int n1 = 5;
  27.     Int n2 = 10.9257; // This will automatically convert the value to int(floor, so the value will be 10).
  28.         
  29.     // Supports section comments
  30.     Bool /*Yup, this is a section comment*/ bool2 = false;
  31.     /*Another section comment*/ Bool bool2 = false;
  32.     Bool /* section comment */bool3 /*another section comment*/ = true/*yet another section comment*/; /*and another*/ // And another…
  33.     
  34.     // Supports vectors too!!!
  35.     Vector2 vec2 = ( 1.0, 3.0f /*appending 'f' is optional*/ ); // 2D Vectors
  36.     Vector3 vec3 = ( 1.0, 3.0, 2.578 );                            // 3D Vectors
  37.     Vector4 vec4 = ( 1.0, 3.0 , 2.578, 3.14159265 );            // 4D Vectors or Quaternions
  38.     /* If you haven't noticed I just pulled a pi there. lolz */
  39.     
  40.     /* Supports recursive sections (sections inside a section) */
  41.     Section Mesh
  42.     {
  43.         Section Material
  44.         {
  45.             String mergeMode    = "Blend";
  46.             String bumpMap        = "bump.tga";
  47.             String textureName    = "MeshTexture.tga";
  48.         };
  49.         
  50.         String meshName = "tiny.x"; // The infamouse DX character
  51.     };
  52.     
  53.     // Array of ints.
  54.     Int[5] indices1 = { 1, 2, 3, 4, 5 }; // We can explicitly define the size of an array
  55.     Int[9] indices2 = { 1, 2, 3,    \\par                         4, 5, 6,    \\par                         7, 8, 9,    \\tab \\ comma at the end is optional
  56.     };
  57.     // NOTE: Another important thing is that only arrays and strings can define values in multiple lines.
  58.     Float[3] floatArray = { 3.256, 1.23, 456.789 };    // Float arrays
  59.     
  60.     Vector2[2] vert2dArray1 = { (3.0, 2.0), (2.56, 1.23) };
  61.     Vector2[3] vert2dArray2 = { (3, 2.0), (2.56, 1.23),    \\par                                  (1.23, 4.56) };
  62.     /*
  63.      You can't do things like this though:
  64.         Vector3[2] bla = { ( 1.2, 2.2, \ // <— Incomplete
  65.             2.1 ), (1,2,3 )};
  66.     */
  67.     // TODO: We still need to implement these…
  68.     // Same variable name implicitly overrides the older one. Do something about this.
  69.     // Int[] indices3 = { 6,7,8,9,10 }; // We can probably do something like this in the future…
  70. };

Code Listing 2: Sample data creation script. Download it here[3]

 

Bibliography:

1. PulseScript.h, http://codaset.com/codesushi/pulse-tec/source/master/blob/Source/Engine/Include/PulseScript.h

2. PulseScript.cpp, http://codaset.com/codesushi/pulse-tec/source/master/blob/Source/Engine/Source/PulseScript.cpp

3. Sample PulseScript script code, http://codaset.com/codesushi/pulse-tec/source/master/blob/Source/Engine/Demo/SampleScript.ps

- MrCodeSushi

Game System Registry With Integrated Simple Unit Testing Framework

This system I will share today is roughly adopted from Guillaume Blanc’s Registrer(Registry) system[1]. This Registry system is designed to keep track all registered classes and objects in an easy, global, and manageable manner. This system can easily send events such as initialization, shutdown, unit testing, or anything else that you can imagine and each registered systems/objects can react to a specified event. If this sounds very familiar to you, chances are you’ve already heard this in your Design Patterns class. Yes, this is the dispatcher-listener design pattern. An object or a system (aka listener) registers to the Registry(aka dispatcher) and when the Registry signals a message, it sends a message to each and every registered listeners.

There are two types the Registry accepts. One is a class (static classes) and the second is an instantiated object. An interface class will play a big role on these two types in order for them to be accepted by the Registry. Code listing 1 shows the interface class.

Code Listing 1
class IRegistryObject : private NonCopyable
{
public:
    // Initialize object priority
    IRegistryObject( ERegistryPrimaryPriority::Type primaryPriority, ERegistrySecondaryPriority::Type secondaryPriority, BOOL bRegisterObject = TRUE );
    virtual ~IRegistryObject ( void );

protected:
    friend Registry;

    // Registry object operation handling
    virtual BOOL DoRegistryOperation( ERegistryOperation::Type op ) = 0;
    // Less than registry object comparison
    static BOOL IsLessPriority( const IRegistryObject *plhs, const IRegistryObject *prhs );

private:

    ERegistryPrimaryPriority::Type m_primaryPriority;
    ERegistrySecondaryPriority::Type m_secondaryPriority;
};

As you can see in Code Listing 1, the abstract base class needs the derived classes to define DoRegistryOperation(). DoRegistryOperation() method is the entry point for all the events sent by the Registry.

You may also have noticed that the constructor accepts two parameters named ERegistryPrimaryPriority and ERegistrySecondaryPriority. These enums defines the priority of the Registry Object from lowest to highest priority. These priorities are very important as they control the order of the registered objects to call. What you can do is probably set very important systems or classes having the highest priority without dependencies. Less important systems or systems that requires dependencies would obviously need to be set in a lower priority than the dependency it requires.

For registering an instantiated object, one would simply inherit the class with IRegistryObject then calling IRegistryObject’s constructor to automatically register it in the Registry.

For classes, it takes a little bit more of explaining to do. The problem with this is that, there are no actual objects to register in the Registry. So what we would do is create a class that encapsulates or connect the class in question in some way. Thus, we devised a macro to do exactly like that. Take a look at Code Listing 2.

Code Listing 2
#define PSX_START_REGISTRY_OBJECT( _class_, primaryPriority, secondaryPriority )    \\par     class RegistryObject##_class_ : public IRegistryObject    \\par     {    \\par     public:    \\par         RegistryObject##_class_##( void ) : IRegistryObject( primaryPriority, secondaryPriority ) { } \\par         virtual BOOL DoRegistryOperation( ERegistryOperation::Type op );    \\par     };    \\par     static RegistryObject##_class_ gRegistryObject##_class_##;    \\par     \\par     BOOL RegistryObject##_class_##::DoRegistryOperation( ERegistryOperation::Type op )    \\par     {    \\par         switch( op ) \\par         {

#define PSX_END_REGISTRY_OBJECT( )    \\par         default:    \\par         break; \\par         }    \\par         return TRUE;    \\par     }

#define PSX_REGISTRY_ON_INITIALIZE()    break; case ERegistryOperation::INITIALIZE:
#define PSX_REGISTRY_ON_SHUTDOWN()        break; case ERegistryOperation::SHUTDOWN:
#define PSX_REGISTRY_ON_TEST()            break; case ERegistryOperation::TEST:

Quite scary, no? Well, don’t be. These are just predefined preprocessors that basically replaces everything in code that finds the same name as the defined name. What these macro does is that it declares a new class, derived from IRegistryObject , and defines the DoRegistryOperation() method. The DoRegistryOperation() is actually empty and you’ll be the one to write code into it let be initialization, shutdown, or test code using the PSX_REGISTRY_ON…() macro declarations. Code Listing 3 shows a sample on how the macros are used.

Code Listing 3
PSX_START_REGISTRY_OBJECT( String, ERegistryPrimaryPriority::Normal, ERegistrySecondaryPriority::Normal )
    PSX_REGISTRY_ON_TEST()
    {
        String str1 = "Hello World.";
        PSX_Assert( str1.GetLength() == 12, "Length should be 12." );

        SIZE_T index = str1.FindFirstOf( "l" );
        PSX_Assert( index == 2, "Index should be 2." );

        index = str1.FindFirstNotOf( "H" );
        PSX_Assert( index == 1, "index should be 1." );

        String str2 = str1.SubString( index );
        PSX_Assert( PSX_StrCmp( str2.GetCString(), PSX_String("ello World.") ) == 0, "Substring method failed." );

        return TRUE;
    }
PSX_END_REGISTRY_OBJECT();

Code Listing 3 shows registering a String class to the Registry and defining a Unit Test code for code testing.[2] Please study Code Listing 2 and Code Listing 3 to fully grasp and understand what it is trying to do.

And lastly, I present to you the Registry class shown in Code Listing 4.

Code Listing 4
class Registry
{
public:

    static BOOL ExecuteOperation( ERegistryOperation::Type op );

private:

    static void RegisterObject( IRegistryObject *pObj );

    static void UnregisterObject( IRegistryObject *pObj );

private:

    friend IRegistryObject;
    friend RegisterClassRAII;
    friend class TestRAII;

    // Custom compare trait for sorting registry objects based on their priority
    template < typename T >
    class RegistryObjectLessThan
    {
    public:
        BOOL operator () ( const T &lhs, const T &rhs ) const
        {
            return IRegistryObject::IsLessPriority( lhs, rhs );
        }
    };

    typedef SortedLList< IRegistryObject *, RegistryObjectLessThan<IRegistryObject *> > ObjectList;

    static ObjectList *m_pObjectList;

};

There’s nothing much really to discuss here. Registry objects simply register themselves by calling Registry::RegisterObject and they will be registered in the Registry. UnregisterObject removes them from the Registry.

Last Thoughts and Further Improvements

You may have noticed that the Registry class uses a SortedList (SortedLList). It is basically a sorted linked-list. That being said, it won’t be a good idea to register lots and lots of instantiated objects. This system is designed to handle application/game systems at best. Such systems would be a memory manager, Sound System, Input System, Grpahics System, etc… If you want to make it handle a great amount of instantiated objects then you may have to change a more capable container such as a vector, hash-table or a map for example.

Implementation

Full implementation of the Registry system/class can be found here[3].

Bibliography

  1. Guillaume Blanc, Article source code, Registrer, Cross platform rendering thread, ShaderX7, 2009
  2. Pulse::String class, http://codaset.com/codesushi/pulse-tec/source/master/blob/Source/Engine/Include/String.h, http://codaset.com/codesushi/pulse-tec/source/master/blob/Source/Engine/Source/String.cpp
  3. Pulse::Registry class, http://codaset.com/codesushi/pulse-tec/source/master/blob/Source/Engine/Include/Registry.h, http://codaset.com/codesushi/pulse-tec/source/master/blob/Source/Engine/Source/Registry.cpp

Don’t forget a good dose of Mr. Louis Armstrong song!

What a Wonderful WOrld–Louis Armstrong

 

– MrCodeSushi

Your Own custom abstract IOStream interface

This is more of an obvious avoidable problem than a necessary work/solution. But I needed this on how I was working on my own little “engine”. A couple of months ago, I was working on a Virtual File System. I later discovered that std::fstream has a 4GB limit. So I resorted to using the Stream I/O instead which can handle greater than the 4GB limit. The problem with this is that it isn’t structured in an Object-Oriented way. Yes we want everything to be Object-Oriented. That being said, I ended up wrapping the Stream I/O into a neat simple to use class[1][2].

Now I’m working on a new system which requires a generic way to input and output streams. What I mean is that I want my system to not care where the system is reading in or writing out data. Let it be reading in from an input peripheral, reading from a file, writing to a console or writing to a file. So I designed a very simple abstract I/O stream class. It is broken down into two classes, IStream and OStream, which is derived from a base Stream class[3].

These abstract classes are definitely far from complete. But it seems to serve well for my purpose. So I can at least say that this is a good start.

If you take a look at the implementations provided, you’ll notice that only the FileIO class is currently derived from it right now. I still have to add a bunch of derived classes to encapsulate cin, cout, and a bunch of others that I can think of which is currently in my TODO list that I have to do sometime in the future(no pun intended).

Links:

1. FileIO.h – http://codaset.com/codesushi/pulse-tec/source/master/blob/Source/Engine/Include/FileIO.h

2. FileIO.cpp – http://codaset.com/codesushi/pulse-tec/source/master/blob/Source/Engine/Source/FileIO.cpp

3. Steam.h – Stream, OStream, IStream – http://codaset.com/codesushi/pulse-tec/source/master/blob/Source/Engine/Include/Stream.h

Dashing Song to Listen to:

Andrews Sisters–I’ve Got A Guy In Kalamazoo