Game Design and Programming

Objectives Classify the games How games are design How games are implemented What are the main components of a game engine

Designing Games 3D mathematics for games may be hard but designing games is even harder Having a fun game is a challenging issue If the game is not well-design, the fancy 3D graphics will not do any help Coming up with a game idea is usually not difficult:  The level of Details, final implementation, and the look make the difference between professional and novice games

Types of games The first step for designing a game is to the genre of your game:  Action and Adventure  Fighting games  Sport games  Strategy/war games  Pure puzzle and board games  Mechanical simulations Flying, boating, racing, etc.  Ecosystem simulations Artificial system of some kind such as ant colony, city, etc.

Action & Adventure Strategy/War Sports Puzzles

Simulation: Racing Fighting Ecosystem simulation

Brainstorming Once the type of the game is specified, you must come up with a fun game Brainstorm and through ideas. Existing games, reading science fiction books, and watching 3D movies can trigger your creativity. Keep it simple: don’t bite off more than what you can chew!

Design document and Storyboard Once the ideas are set in your mind, you need to get them on paper A design document outlines the details of the game:  Who are the main characters?  What is the main idea of the game?  How to win the game?  What are the levels of the game?  What are the cool features in the game? Making a storyboard is often the best to start and understand the game

Is it Fun? Reality check:  Will the game be fun?  Will people enjoy it?  Are the “cool features” cool enough to attract people? Be objective and see the game from others’ eyes Remember that the cool features and the attention to details make the game fun

The big picture!

The components of a game A game is a real-time application that includes:  Interactivity: mouse, keyboard, joystick  Visual: the frames drawn into the display  Audio: any sound or music playing during playing A video game is:  A continuous loop that performs logic and draws an image on the screen, usually at a rate of 30 frames per second (fps) or more.  This is similar to how a movie is displayed, except that you are creating the movie as you play.

Components of a game (2) The main game loop! while (!gameover) { get input process input simulate physics and AI redraw } Simple!

The components of a game (3) Initialization  perform the usual operations Memory allocation Graphics device creation and initialization Resource acquisition Loading data from disk. Game Loop  This is the main loop of the game.  It is where the actions of the game begin and continue until the user exists the main game loop.

The components of a game (4) Interactivity  retrieves player inputs  Process the inputs or buffer them for later use in Artificial Intelligence (AI) and game logic AI and Game Logic  The majority of the game code is in here  The artificial intelligence, the physics, and the logic of the game are executed  the results are used to draw the next frame on the screen

The components of a game (4) Rendering  the results of the player’s input and the execution of game AI and logic are used to generate the next frame of animation for the game.  This frame is usually drawn on an off-screen (back) buffer area  A swapping of the front and the back buffer is performed to display the frame.

The components of a game (5) Display synchronization  To avoid a variable frame rate, you must set the frame rate to a fixed value  Use timing/waiting functions to hold the frame rate to a fixed value Cleaning up  When the user exits the game, we have to make sure to release the resources and clean up the system: Delete any pointers Close any files, databases, or connections Return to the window mode if full-screen mode is used

How to control the main loop? The game main loop is usually a finite state machine (FSM) that contains a number of states and the transitions between these states

Show us the code! // implementation of main game loop while (gameState!=GAME_EXIT) { // what state is game loop in switch (gameState) { case GAME_INIT: // the game is initializing // allocate all memory and load the resources initialize(); // move to menu state gameState = GAME_MENU; break; case GAME_MENU: // the game is in the menu mode // call the main menu function and let it switch states gameState = getMenuChoice(); // You can force a RUN state here if you want. break; case GAME_STARTING: // the game is about to run // this state is optional, but usually used to set things up right // before the game is run you might do a little more house keeping here setupForRun(); // switch to run state gameState = GAME_RUN; break;

Show us the code! (2) case GAME_RUN: // the game is now running // this section contains the entire game logic loop // clear the display clearDisplay(); // get the inputs and interact with the user getInput(); // perform logic and AI doLogicAI(); // display the next frame of animation renderFrame(); // synchronize the display wait(); // the only way that state can be changed is through user interaction in the input // section or by maybe losing the game. break; case GAME_RESTART: // the game is restarting // this section is a cleanup state used to put things in order before running again fixUp(); // switch states back to the menu gameState = GAME_MENU; break;

Show us the code! (3) case GAME_EXIT: // the game is exiting // if the game is in this state, then cleanup everything releaseCleanUp(); // set the error word to whatever error = 0; break; default: break; } // end switch } // end while // return error code to operating system return(error);

What is a game engine? Provides the core functionality of the game Allows for reusable software platform and rapid development of games Think of the engine of a car! A game engine usually includes:  A 2D/3D rendering engine  A physics/Collision detection engine  AI  Sound  Processing inputs  Networking Example, Crystal space is an open source game engine

Summary Do you know this? Of course!

For Later Algorithms, data structures, and programming tricks for games Physics and mathematics for games Artificial intelligence:  Determinism  Randomness