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

Time for action – taking the zoom level into account


As a last detail, I would like to mention that you can draw an item differently depending on its scale. To do that, the level of detail can be used. You use the passed pointer to QStyleOptionGraphicsItem of the item's paint function and call levelOfDetailFromTransform() with the painter's world transformation. We change the paint function of the ScaleItem item to the following:

const qreal detail = option->levelOfDetailFromTransform(painter->worldTransform());
const QColor fillColor = (detail >= 5) ? Qt::yellow : Qt::red;

What just happened?

The detail parameter now contains the maximum width of unity square, which was mapped to the painter coordinate system via the painter's world transformation matrix. Based on that value, we set the fill color of the border rectangles to yellow or red. The expression detail >= 5 will become true if the rectangle is displayed at least five times as large as in a normal state. The level of...