Guide to Developing Video Games

7/29/2019 Guide to Developing Video Games

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Video Games

VGD 2012-2013

Francis Joseph Seria


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Goals

To understand the fundamental modules running in agame

To understand the fundamental structure of all videogames


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Objectives

Identify and implement the fundamental structure of allvideo games in C++

Identify and implement the different modules in a videogame


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Core Values

Creativity Free your mind

Curiosity Your thirst for knowledge can never be quenched

Patience Everything will turn out just right


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As a Software

Video Games are fundamentally, software.Development of Video Games follow SoftwareEngineering Practices and Methods.

Unlike Business applications, a Video Game shouldcontinue with or without User Input.

A major difference between Video Games and othersoftware is that development teams include more than

just programmers. They include artists, level designers,writers, etc. similar to movie production.


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Video Games

Video Games always require a computer to receiveplayer input, perform logic and return feedback to theplayer.

Thus, card games and board games are not consideredVideo Games (even if they have Video Game versions).


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Modules & Managers

Elements of a Video Game


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Sample Modules


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Sample Modules

A Video Game is comprised of different systems workingtogether

Each system is further divided into subsystems. For example: Game Logic may consist of Physics and AI Graphics may include 2D and 3D Resources may handle images, meshes, audio sources, etc.

Each module may have a Manager that would handle allthe subsystems and their interactions between other systems

Most of the modules correspond to specific hardware types


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Specialized Modules

There are devices which have specialized hardware forspecific modules. For example: Physics Modules (Physics Processing Units) Post Rendering Effects (Digital Signal Processor) Network Module Logging (Debugging)


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Game Manager

The Game Manager is the core of a Video Game.Ideally, it is the entry and exit point of the program. Thegame manager initializes the other modules in the game.

All objects in the scene that are either visible, has logic orboth is managed by the Game Manager. These objectsare commonly called Game Objects.

Game Objects are anything that is visible or has logic The Game Manager handles the Game Loop


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Time Manager

The Time Manager (or Timer) keeps track of the amountof time between iterations of the game loop

Usually measured in milliseconds Other information that the Timer may keep track of: Time elapsed since the Video Game started Time elapsed between video output (to determine or

control frames per second)


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Input Manager

The Input Manager (or simply Input) records the states of allavailable input devices to be used

Input devices may differ per platform as listed: For Desktop/Laptops; keyboard, joystick, mouse, webcam,

microphone, etc.

For Consoles/Handhelds; game pad buttons, joystick, IR, deviceorientation or motion, multi-touchscreen, camera, microphone,etc.

Other information the Input may record: Duration of an input state (ex: charging of a weapon) Events or Change of state of an input (ex: on press, on release) Order of consecutive events (ex: combo, double click)


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Output Manager

The Output Manager (or simply Output) handlesfeedback to the player

Output is usually split into Audio and Video subsystems The Audio subsystem control the playing of music and

sound effects

The Video subsystem manages the visual feedback tothe player, which may be in 2D, 3D or both


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The Game Loop

Fundamental Structure for all Video Games


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The Game Loop


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The Game Loop

As mentioned before, Video Games should continueprocessing whether the user has entered any input or not

Thus, we cannot use blocking input functions such asscanf() orcin to receive input. Instead, we save thestates of all input devices to be used later on

Then, we update the logic of the game and return anoutput before we repeat the cycle

Each cycle in the game loop is called a frame, similar tothe frames of a movie. After all, a video game is aninteractive movie J


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The Game Loop

bool isPlaying = true;

if (!Init()) return -1;

// Enter the game loop

while (isPlaying) {

Input();

Update();Output();

}

CleanUp();


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Init() and CleanUp()

Init() is used for initializing the video game, initializing themodules and loading resources

CleanUp() is used for releasing resources and shuttingdown the other modules

Note: The constructor and destructor may be used instead of Init()

and CleanUp()

These 2 functions are not part of the game loop


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Input()

Input() calls the Input Manager to recheck all the statesfrom the input devices


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Update()

Update() contains thelogic of the Video Game

Objects react to playerinput or collisions

Collision Tests, Physics andAI are also executed in the

Update

May not exactly be in theorder as shown


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Output()

Output() gives the playerfeedback

Output devices differ perplatform but they generally

involve both Video and

Audio

Rather than displayingdirectly to the screen, weput the output in a buffer


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Exiting the Game Loop

The Game Loop, and eventually the game itself, exitswhen the condition (

isPlaying) becomes false

Guide to Developing Video Games

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