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 – creating a regular polygon item


Let's learn about the scene-graph by delivering an item class for rendering convex regular polygons. We will draw the polygon using the OpenGL drawing mode called "triangle fan." It draws a set of triangles that all have a common vertex. Subsequent triangles are defined by the shared vertex, the vertex from the previous triangle, and the next vertex specified. Have a look at the diagram to see how to draw a hexagon as a triangle fan using 8 vertices as control points:

The same method applies for any regular polygon. The first vertex defined is always the shared vertex occupying the center of the shape. The remaining points are positioned on the circumference of a bounding circle of the shape at equal angular distances. The angle is easily calculated by dividing the full angle by the number of sides. For a hexagon, this yields 60 degrees.

Let's get down to business and the subclass QQuickItem. We will give it a very simple interface:

class RegularPolygon...