1. 3D Development with Qt

2. Agenda
3D Concepts
OpenGL
Qt + OpenGL

5. We need an API

6.
Graphics rendering API

7. Current industry standard for 3D graphics
( Hi DirectX! )

8. MultiPlatform
MultiLanguage
Hardware Independent
Open Standard

9. More than 250 functions to produce
three­dimensional scenes
glColor, glVertex, glTranslate, glRotate ...

10. Geometric Primitives

12. Camera
Physical locations
Projection properties

13. Lighting
glEnable ( GL_LIGHTING )
Lighting simulates how objects reflect light
Material composition
Light’s color and position
Two sided
GLfloat mred[4]= {1,0,0,1};
glMaterialfv(GL_FRONT, GL_AMBIENT, mred);

14. Primitives are specified:
glBegin(primitiveType);
…
…
glEnd();
Example:
glBegin(GL_TRIANGLES);
glVertex3f( 0.0, 1.0, 0.0 );
glVertex3f( ­1.0, ­1.0, 0.0 );
glVertex3f( 1.0, ­1.0, 0.0 );
glEnd();

15. Color

16. The human eye has 3 types of light receptor
cells
glColor3f ( GLfloat red, GLfloat green, GLfloat blue );

17. glBegin(GL_TRIANGLES);
// red
glColor3f( 1.0, 0.0, 0.0 );
glVertex3f( 0.0, 1.0, 0.0 );
// green
glColor3f( 0.0, 1.0, 0.0 );
glVertex3f( ­1.0, ­1.0, 0.0 );
// blue
glColor3f( 0.0, 0.0, 1.0 );
glVertex3f( 1.0, ­1.0, 0.0 );
glEnd();

18. Shading
Smooth:
glShadeModel ( GL_SMOOTH );
Flat:
glShadeModel ( GL_FLAT );

19. // Smooth shading
glShadeModel(GL_SMOOTH);
glBegin(GL_TRIANGLE_STRIP);
glColor3( 0.0, 0.5, 0.0 );
glVertex3( ­1.0, ­0.5, ­5.0 );
glColor3( 1.0, 0.0, 0.0 );
glVertex3( 1.0, ­0.5, ­5.0 );
glColor3( 1.0, 0.0, 0.0 );
glVertex3( 0.0, 0.5, ­5.0 );
glColor3( 1.0, 0.0, 0.0 );
glVertex3( 1.5, 0.0, ­5.0 );
glColor3( 0.0, 0.0, 1.0 );
glVertex3( 2.0, ­1.5, ­5.0 );
glEnd();

20. // Flat shading
glShadeModel(GL_FLAT);
glBegin(GL_TRIANGLE_STRIP);
glColor3( 0.0, 0.5, 0.0 );
glVertex3( ­1.0, ­0.5, ­5.0 );
glColor3( 1.0, 0.0, 0.0 );
glVertex3( 1.0, ­0.5, ­5.0 );
glColor3( 1.0, 0.0, 0.0 );
glVertex3( 0.0, 0.5, ­5.0 );
glColor3( 1.0, 0.0, 0.0 );
glVertex3( 1.5, 0.0, ­5.0 );
glColor3( 0.0, 0.0, 1.0 );
glVertex3( 2.0, ­1.5, ­5.0 );
glEnd();

21.
glTexParameteri( GL_TEXTURE_2D,GL_TEXTURE_MIN_FILTER, GL_LINEAR );

23. +
Qt OpenGL module

24. #include <QGLWidget>
class GLWidget : public QGLWidget
{
Q_OBJECT
public:
GLWidget( QWidget *parent=0 );
~GLWidget();
...
protected:
void initializeGL();
void resizeGL( int width, int height );
void paintGL();
private:
...
};

25. void initializeGL();
void resizeGL( int width, int height );
void paintGL();

26. void GLWidget::initializeGL()
{
// Smooth shading
glShadeModel( GL_SMOOTH );
// Background color
glClearColor( 0.0f, 0.0f, 0.0f, 0.0f ); ­> qglClearColor( Qt::black );
// Depth buffer setup
glClearDepth( 1.0f );
// Enable depth testing
glEnable( GL_DEPTH_TEST );
// Set type of depth test
glDepthFunc( GL_LEQUAL );
}

27. void GLWidget::resizeGL( int width, int height )
{
if ( height == 0 )
height = 1;
// Reset current viewport
GlViewport( 0, 0, width, height );
// Select projection matrix
GlMatrixMode( GL_PROJECTION );
// Reset projection matrix
glLoadIdentity();
// Select modelview matrix
GlMatrixMode( GL_MODELVIEW );
// Reset modelview matrix
glLoadIdentity();

28. void GLWidget::paintGL()
{
glClear ( GL_COLOR_BUFFER_BIT );
// Reset the drawing perspective
glLoadIdentity();
// triangle
glBegin (GL_TRIANGLES);
GlColor3f ( 1.0, 0.0, 0.0 );
glVertex3f ( 5.0, 5.0, 0.0 );
glColor3f ( 0.0, 1.0, 0.0 );
glVertex3f ( 25.0, 5.0, 0.0 );
glColor3f ( 0.0, 0.0, 1.0 );
GlVertex3f ( 5.0, 25.0, 0.0 );
glEnd();
}

29. void GLWidget::drawtriangle()
{
glBegin ( GL_TRIANGLES );
glColor3f ( 1.0, 0.0, 0.0 );
glVertex3f ( 5.0, 5.0, 0.0 );
glColor3f ( 0.0, 1.0, 0.0 );
glVertex3f ( 25.0, 5.0, 0.0 );
glColor3f ( 0.0, 0.0, 1.0 );
glVertex3f ( 5.0, 25.0, 0.0 );
glEnd();
}
void GLWidget::paintGL()
{
glClear ( GL_COLOR_BUFFER_BIT );
// Reset the drawing perspective
glLoadIdentity();
drawTriangle();

30. Demo Animation

31. Demo Rotation

32. Thanks
Ronny Yabar Aizcorbe
ronnycontacto@gmail.com
ronnyml.wordpress.com