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 – implementing the ability to scale the scene


Let's do the scaling first. We add the item to a scene and put that scene on a custom view we have subclassed from QGraphicsView. In our customized view, we only need to reimplement wheelEvent() as we want to scale the view by using the mouse's scroll wheel.

void MyView::wheelEvent(QWheelEvent *event) {
  const qreal factor = 1.1;
  if (event->angleDelta().y() > 0)
    scale(factor, factor);
  else
    scale(1/factor, 1/factor);
}

What just happened?

The factor parameter for the zooming can be freely defined. You can also create a getter and setter method for it. For us, 1.1 will do the work. With event->angleDelta(), you get the distance of the mouse's wheel rotation as a QPoint pointer. Since we only care about vertical scrolling, just the y axis is relevant for us. In our example, we also do not care about how far the wheel was turned because, normally, every step is delivered separately to wheelEvent(). But if you...