Book Image

Game Programming Using Qt: Beginner's Guide

By : Lorenz Haas, Witold Wysota, Witold Wysota, Lorenz Haas
Book Image

Game Programming Using Qt: Beginner's Guide

By: Lorenz Haas, Witold Wysota, Witold Wysota, Lorenz Haas

Overview of this book

Qt is the leading cross-platform toolkit for all significant desktop, mobile, and embedded platforms and is becoming more popular by the day, especially on mobile and embedded devices. Despite its simplicity, it's a powerful tool that perfectly fits game developers’ needs. Using Qt and Qt Quick, it is easy to build fun games or shiny user interfaces. You only need to create your game once and deploy it on all major platforms like iOS, Android, and WinRT without changing a single source file. The book begins with a brief introduction to creating an application and preparing a working environment for both desktop and mobile platforms. It then dives deeper into the basics of creating graphical interfaces and Qt core concepts of data processing and display before you try creating a game. As you progress through the chapters, you’ll learn to enrich your games by implementing network connectivity and employing scripting. We then delve into Qt Quick, OpenGL, and various other tools to add game logic, design animation, add game physics, and build astonishing UI for the games. Towards the final chapters, you’ll learn to exploit mobile device features such as accelerators and sensors to build engaging user experiences. If you are planning to learn about Qt and its associated toolsets to build apps and games, this book is a must have.
Table of Contents (18 chapters)
Game Programming Using Qt
Credits
About the Authors
About the Reviewers
www.PacktPub.com
Preface
Index

Optimization


Let us now take a look at some of the optimizations we can perform to speed up the scene.

A binary space partition tree

The scene constantly keeps record of the position of the item in its internal binary space partition tree. Thus, on every move of an item, the scene has to update the tree, an operation that can become quite time-and memory-consuming. This is especially true of scenes with a large number of animated items. On the other hand, the tree enables you to find an item (for example, with items() or itemAt()) incredibly fast even if you have thousands of items.

So when you do not need any positional information about the items—this also includes collision detection—you can disable the index function by calling setItemIndexMethod(QGraphicsScene::NoIndex). Be aware, however, that a call to items() or itemAt() results in a loop through all items in order to do the collision detection, which can cause performance problems for scenes with many items. If you cannot relinquish...