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 – making the diagram more colorful


The diagram serves its purpose, but it looks a bit dull. Add some shine to it by defining three new color properties in the canvas object–color, topColor, bottomColor–and setting their default values to black, red, and blue, respectively.

Since points and arg should not really be public properties that anyone can change behind our backs, we'll correct it now. Declare a child element of the canvas of QtObject and set its ID to priv. Move declarations of points and arg inside that object. Move the onArgChanged handler there, as well:

QtObject {
  id: priv
  property var points: []
  property real arg: -Math.PI

  onArgChanged: {
    points.push(func(arg))
    points = points.slice(-canvas.width)
    canvas.requestPaint()
  }
}

Then, search through the whole code and prefix all occurrences of arg and points outside the newly declared object with priv, so that each of their invocations lead to the priv object.

Then, let's make use of the three colors...