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

The cross-platform programming


Qt is an application programming framework that is used to develop cross-platform applications. What this means is that software written for one platform can be ported and executed on another platform with little or no effort. This is obtained by limiting the application source code to a set of calls to routines and libraries available to all the supported platforms, and by delegating all tasks that may differ between platforms (such as drawing on the screen and accessing system data or hardware) to Qt. This effectively creates a layered environment (as shown in the following figure), where Qt hides all platform-dependent aspects from the application code:

Of course, at times we need to use some functionality that Qt doesn't provide. In such situations, it is important to use conditional compilation like the one used in the following code:

#ifdef Q_OS_WIN32
// Windows specific code
#elif defined(Q_OS_LINUX) || defined(Q_OS_MAC)
// Mac and Linux specific code
#endif

Tip

Downloading the example code

You can download the example code files from your account at http://www.packtpub.com for all the Packt Publishing books you have purchased. If you purchased this book elsewhere, you can visit http://www.packtpub.com/support and register there to have the files e-mailed directly to you.

What just happened?

Before the code is compiled, it is first fed to a preprocessor that may change the final text that is going to be sent to a compiler. When it encounters a #ifdef directive, it checks for the existence of a label that will follow (such as Q_OS_WIN32), and only includes a block of code in compilation if the label is defined. Qt makes sure to provide proper definitions for each system and compiler so that we can use them in such situations.

Tip

You can find a list of all such macros in the Qt reference manual under the term "QtGlobal".

Qt Platform Abstraction

Qt itself is separated into two layers. One is the core Qt functionality that is implemented in a standard C++ language, which is essentially platform-independent. The other is a set of small plugins that implement a so-called Qt Platform Abstraction (QPA) that contains all the platform-specific code related to creating windows, drawing on surfaces, using fonts, and so on. Therefore, porting Qt to a new platform in practice boils down to implementing the QPA plugin for it, provided the platform uses one of the supported standard C++ compilers. Because of this, providing basic support for a new platform is work that can possibly be done in a matter of hours.

Supported platforms

The framework is available for a number of platforms, ranging from classical desktop environments through embedded systems to mobile phones. The following table lists down all the platforms and compiler families that Qt supports at the time of writing. It is possible that when you are reading this, a couple more rows could have been added to this table:

Platform

QPA plugins

Supported compilers

Linux

XCB (X11) and Wayland

GCC, LLVM (clang), and ICC

Windows XP, Vista, 7, 8, and 10

Windows

MinGW, MSVC, and ICC

Mac OS X

Cocoa

LLVM (clang) and GCC

Linux Embedded

DirectFB, EGLFS, KMS, and Wayland

GCC

Windows Embedded

Windows

MSVC

Android

Android

GCC

iOS

iOS

LLVM (clang) and GCC

Unix

XCB (X11)

GCC

RTOS (QNX, VxWorks, and INTEGRITY)

qnx

qcc, dcc, and GCC

BlackBerry 10

qnx

qcc

Windows 8 (WinRT)

winrt

MSVC

Maemo, MeeGo, and Sailfish OS

XCB (X11)

GCC

Google Native Client (unsupported)

pepper

GCC