Book Image

OpenGL Game Development By Example

By : Stephen Madsen, Robert Madsen
Book Image

OpenGL Game Development By Example

By: Stephen Madsen, Robert Madsen

Overview of this book

OpenGL is one of the most popular rendering SDKs used to develop games. OpenGL has been used to create everything from 3D masterpieces running on desktop computers to 2D puzzles running on mobile devices. You will learn to apply both 2D and 3D technologies to bring your game idea to life. There is a lot more to making a game than just drawing pictures and that is where this book is unique! It provides a complete tutorial on designing and coding games from the setup of the development environment to final credits screen, through the creation of a 2D and 3D game. The book starts off by showing you how to set up a development environment using Visual Studio, and create a code framework for your game. It then walks you through creation of two games–a 2D platform game called Roboracer 2D and a 3D first-person space shooter game–using OpenGL to render both 2D and 3D graphics using a 2D coordinate system. You'll create sprite classes, render sprites and animation, and navigate and control the characters. You will also learn how to implement input, use audio, and code basic collision and physics systems. From setting up the development environment to creating the final credits screen, the book will take you through the complete journey of creating a game engine that you can extend to create your own games.
Table of Contents (19 chapters)
OpenGL Game Development By Example
Credits
About the Authors
About the Reviewers
www.PacktPub.com
Preface
Index

The state of the game


Remember when we coded the pause button back in Chapter 4, Control Freak? We had to add some code that told the game whether it was active or paused. In fact, we defined the following enums:

enum GameState
{
  GS_Running,
  GS_Paused
};

These enums defined two game states: GS_Running, and GS_Paused. We then set the default game state to GS_Running in the StartGame function:

void StartGame()
{
  inputManager = new Input(hWnd);
  LoadTextures();
  m_gameState = GS_Running;
  
  srand(time(NULL));
  pickupSpawnThreshold = 5.0f;
  pickupSpawnTimer = 0.0f;
}

As long as the game state is set to GS_Running, then the game continues to cycle through the game loop, processing updates, and rendering the scene. However, when you click the pause button, the game state is set to GS_Paused. When the game is paused, we no longer update the game objects (that is, the robot, pickups, and enemies), but we do continue to render the scene and process the UI (user interface) so that buttons...