Qt is a cross-platform application development framework for building graphical user interfaces. It includes libraries for core functionality, GUI components, and XML handling. The main tools that come with Qt are the Meta Object Compiler (moc) for C++ extensions, Qt Designer for visually creating GUIs, Qt Linguist for internationalization, qmake for automating builds, and Qt Creator as an integrated development environment. Qt uses a scene graph with group, property, and shape nodes to render 3D graphics with Coin3D and the SoQt library providing a bridge to 2D Qt interfaces. Example code sets up a root node containing a cube shape, creates an examiner viewer to display the scene graph, and runs the main

1. INTRODUCTION To
Qt

2. What is Qt?
❏ Cross-platform application development
framework.
❏ Used to create graphical user interfaces.
❏ It can be used with several different
programming languages.
❏ “t” in Qt refers to toolkit which defines Qt
much better. Therefore, it can effectively be
defined as a set of tools.

3. Qt TOOLS
❏ The main component is a set of libraries, written
natively in C++. These libraries include: the core library
providing the most important stuff, the GUI library
providing the GUI components, the XML library.
❏ Meta Object Compiler(moc) used to handle Qt’s C++
extensions.This extends C++ a little bit, adding nice
features like the signals/slots mechanism
❏ The GUI designer tool and the UIC. Qt Designer is a
graphical tool to create GUIs visually and save them to
XML files, and the UIC is a command-line tool to
translate those XML files to C++ code.

4. ❏ Qt Linguist, tool to internationalize
applications.Qt Linguist is a graphical tool for
translator to edit those XML files and provide
translations.
❏ The qmake tool, used to automate build
process, so you don't have to run MOC, C++
compiler, UIC and other things manually.
❏ The Qt Creator, a graphical IDE to integrate
all the stuff described above into a single
environment.

5. qmake helps to create .pro file

6. Creating a Qt project

7. File and
t New

8. Select

10. Files generated

11. Examples

16. Similarly a 2D graphic
such as a circle,ellipse
can be built

17. The code uses QPainter on QMainWindow. Circle
drawing is done during gui decoration process , it is
not drawn as an animation.Drawing empty circle on
QMainWindow involves subclassing of
QMainWindow and overriding
paintEvent(QPaintEvent*) method.

19. using Coin3D and SoQt
3-D Graphics in Qt

20. ❏ Coin3D is a high level 3D graphics toolkit for
developing cross-platform 3D visualizations.
❏ It uses scene graph data structures to render
3D graphics.
❏ Based on the de facto standard Open
Inventor, Coin3D is a set of libraries for
creating 3D graphics applications.

21. Coin3D
Few Steps to install

22. 1. Download Coin-3.1.3.tar.gz fom
https://bitbucket.org/Coin3D/coin/downloads.
2. Next unzip the file using the following commands:
o cd /tmp
o gzip -cd Coin-3.1.3.tar.gz | tar xvf -
o mkdir coin-build
3. Run configure from the build directory:cd coin-build
4. ../Coin-3.1.3/configure
5. Build the Coin library:
6. make
7. Install the Coin library:
8. make install

23. Just install:libsoqt40-dev
SoQt is a library which provides bridge
between Coin3D visualistion and Qt
2D Graphical Interface.

24. Linking
Add in the pro file:
LIBS += -lCoin3D -lSoQt

25. Open Inventor
Open Inventor is a “scenegraph“ graphics API:
All visible objects are stored in a scenegraph

26. Capabilities of Open Inventor
❏ Easy construction of 3D scenes
❏ User interaction
❏ Animation

27. Scenegraph Anatomy
There are three kinds of nodes:
Group nodes: allow construction of trees
Property nodes: change the color / location /
... of the next object
Shapes: visible objects.

28. Common node types
❏ Group nodes
SoGroup: SoSeparator..
❏ Property nodes
Transform: SoTransform, SoRotation, ...
Appearance: SoMaterial….
❏ Shape nodes
SoShape SoCone, SoCube,

29. Scene objects
class name prefix: So (scene object)
❏ derived from SoNode
❏ can be inserted directly into the scenegraph
Example:
root->addChild(new SoSphere)

30. #
<Inventor/Qt/viewers/SoQtExaminerViewer.h>
#include <Inventor/nodes/SoSeparator.h>
#include <Inventor/nodes/SoCube.h>
int main(int argc, char ** argv)
{
QWidget * mainwin = SoQt::init(argc, argv,
argv[0]);
SoSeparator * root = new SoSeparator;
root->ref();

31. root->addChild(cube);
SoQtExaminerViewer * eviewer = new
SoQtExaminerViewer(mainwin);
eviewer->setSceneGraph(root);
eviewer->show();
SoQt::show(mainwin);
SoQt::mainLoop();
root->unref();
delete eviewer;
return 0;}

33. #include <Inventor/Qt/SoQt.h>: The SoQt class takes
care of Qt initialisation.
# include<Inventor/Qt/viewers/SoQtExaminerViewer.h>
It is the general purpose viewer to view the 3D object
generated.
#include <Inventor/nodes/SoSeparator.h>
It is subclass of SoGroup class.
#include <Inventor/nodes/SoCube.h>
This is the node for cube shape. It comes under the
category of shape nodes.

34. ❏ QWidget * mainwin = SoQt::init(argc, argv, argv[0]);
SoQt ::init with a string creates a QApplication and its
main window, and returns its window handle.
❏ SoSeparator * root = new SoSeparator;
root->ref();
The root node of the scene graph is created here.
❏ SoCube *cube = new SoCube;
root->addChild(cube);
A cube is added to the scene as a child to the root node.

35. ❏ SoQtExaminerViewer(mainwin);
eviewer->setSceneGraph(root);
eviewer->show();
The ExaminerViewer class of the viewer is used for
display of objects.
❏ SoQt::show(mainwin);
This pops up the main window.
❏ SoQt::mainLoop();
Cleans up all static data allocated by the SoQt library on
initialization.

36. Thank You