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View Full Version : Problem using OpenGL from Qt Application



sujan.dasmahapatra
20th October 2009, 14:10
Dear Friends

I am trying create an OpenGL graphics from within my QT application. I am getting the openGL window but I am unable see any graphicsItem on it.See below the code snippet

class GraphicsView : public QGLWidget
{
Q_OBJECT
public:
GraphicsView();
~GraphicsView();
protected:
void initializeGL();
void paintGL();
private:
QColor trolltechGreen;
QColor trolltechPurple;

GLuint object;
GLuint makeobject();
void quad(GLdouble x1, GLdouble y1, GLdouble x2, GLdouble y2,
GLdouble x3, GLdouble y3, GLdouble x4, GLdouble y4);
void extrude(GLdouble x1, GLdouble y1, GLdouble x2, GLdouble y2);
};

GraphicsView::GraphicsView()
{
object = 0;
trolltechGreen = QColor::fromCmykF(0.40, 0.0, 1.0, 0.0);
trolltechPurple = QColor::fromCmykF(0.39, 0.39, 0.0, 0.0);

}
GraphicsView::~GraphicsView()
{
}

void GraphicsView::initialize()
{
qglClearColor(trolltechPurple.dark());
object = makeObject();
glShadeModel(GL_FLAT);
glEnable(GL_DEPTH_TEST);
glEnable(GL_CULL_FACE);


}

void GraphicsView::paintGL()
{
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glLoadIdentity();
glTranslated(0.0, 0.0, -10.0);
glRotated(xRot / 16.0, 1.0, 0.0, 0.0);
glRotated(yRot / 16.0, 0.0, 1.0, 0.0);
glRotated(zRot / 16.0, 0.0, 0.0, 1.0);
glCallList(object);

}

GLuint GraphicsView::makeobject()
{
GLuint list = glGenLists(1);
glNewList(list, GL_COMPILE);

glBegin(GL_QUADS);

GLdouble x1 = +0.06;
GLdouble y1 = -0.14;
GLdouble x2 = +0.14;
GLdouble y2 = -0.06;
GLdouble x3 = +0.08;
GLdouble y3 = +0.00;
GLdouble x4 = +0.30;
GLdouble y4 = +0.22;

quad(x1, y1, x2, y2, y2, x2, y1, x1);
quad(x3, y3, x4, y4, y4, x4, y3, x3);

extrude(x1, y1, x2, y2);
extrude(x2, y2, y2, x2);
extrude(y2, x2, y1, x1);
extrude(y1, x1, x1, y1);
extrude(x3, y3, x4, y4);
extrude(x4, y4, y4, x4);
extrude(y4, x4, y3, x3);

const double Pi = 3.14159265358979323846;
const int NumSectors = 200;

for (int i = 0; i < NumSectors; ++i) {
double angle1 = (i * 2 * Pi) / NumSectors;
GLdouble x5 = 0.30 * sin(angle1);
GLdouble y5 = 0.30 * cos(angle1);
GLdouble x6 = 0.20 * sin(angle1);
GLdouble y6 = 0.20 * cos(angle1);

double angle2 = ((i + 1) * 2 * Pi) / NumSectors;
GLdouble x7 = 0.20 * sin(angle2);
GLdouble y7 = 0.20 * cos(angle2);
GLdouble x8 = 0.30 * sin(angle2);
GLdouble y8 = 0.30 * cos(angle2);

quad(x5, y5, x6, y6, x7, y7, x8, y8);

extrude(x6, y6, x7, y7);
extrude(x8, y8, x5, y5);
}

glEnd();

glEndList();
return list;


}

void GraphicsView::quad(GLdouble x1, GLdouble y1, GLdouble x2, GLdouble y2,
GLdouble x3, GLdouble y3, GLdouble x4, GLdouble y4)
{
qglColor(trolltechGreen);

glVertex3d(x1, y1, -0.05);
glVertex3d(x2, y2, -0.05);
glVertex3d(x3, y3, -0.05);
glVertex3d(x4, y4, -0.05);

glVertex3d(x4, y4, +0.05);
glVertex3d(x3, y3, +0.05);
glVertex3d(x2, y2, +0.05);
glVertex3d(x1, y1, +0.05);
}

void GraphicsView::extrude(GLdouble x1, GLdouble y1, GLdouble x2, GLdouble y2)
{
qglColor(trolltechGreen.dark(250 + int(100 * x1)));

glVertex3d(x1, y1, +0.05);
glVertex3d(x2, y2, +0.05);
glVertex3d(x2, y2, -0.05);
glVertex3d(x1, y1, -0.05);
}

/////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
// Now I am creating the instance of this openGL window in the mainwindow which is further called in the main.
// My OpenGL black color background window is coming but there's no item that I am creating using makeobject()
MainWindow::startMesh()
{
GraphicsView *view = new GraphicsView(this);
view->show();
}

///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
//////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
Can someone tell me whats going wrong in this !!! Any help would be appreciated
Thanks !

Caius Aérobus
20th October 2009, 14:18
I don't know if you have specific needs but consider using QGLViewer library, most of the functionnalities you can need with OpenGL in Qt should be there.