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 – rotating an item


As an example, let's rotate itemB and itemC by 45 degrees counter-clockwise. For itemB, the function call would look like this:

itemB->setRotation(-45);

The setRotation() function accepts qreal as the argument value, so you can set very precise values. The function interprets the number as degrees for a clockwise rotation around the z coordinate. If you set a negative value, a counter-clockwise rotation is performed. Even if it does not make much sense, you can rotate an item by 450 degrees, which would result in a rotation of 90 degrees. Here is what the two items would look like after the rotation by 45 degrees counter-clockwise:

What just happened?

As you can see, the rotation has its center in the item's origin point. Now you could run into the problem that you want to rotate the rectangle of itemC around its center point. In such a situation, you can use setTransformOriginPoint(). For the described problem, the relevant code would look like this:

QGraphicsRectItem...