Qt Reference Documentation

# glwidget.cpp Example File

opengl/hellogl_es/glwidget.cpp

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     #include "glwidget.h"
     #include <QPainter>
     #include <math.h>

     #include "bubble.h"

     const int bubbleNum = 8;

     inline void CrossProduct(qreal &xOut, qreal &yOut, qreal &zOut, qreal x1, qreal y1, qreal z1, qreal x2, qreal y2, qreal z2)
     {
        xOut = y1 * z2 - z1 * y2;
        yOut = z1 * x2 - x1 * z2;
        zOut = x1 * y2 - y1 * x2;
     }

     inline void Normalize(qreal &x, qreal &y, qreal &z)
     {
         qreal l = sqrt(x*x + y*y + z*z);
         x = x / l;
         y = y / l;
         z = z / l;
     }

     GLWidget::GLWidget(QWidget *parent)
         : QGLWidget(parent)
     {
         qtLogo = true;
         createdVertices = 0;
         createdNormals = 0;
         m_vertexNumber = 0;
         frames = 0;
         setAttribute(Qt::WA_PaintOnScreen);
         setAttribute(Qt::WA_NoSystemBackground);
         setAutoBufferSwap(false);
         m_showBubbles = true;
     }

     GLWidget::~GLWidget()
     {
       if (createdVertices)
           delete[] createdVertices;
       if (createdNormals)
           delete[] createdNormals;
     }

     void GLWidget::setScaling(int scale) {

         if (scale > 50)
             m_fScale = 1 + qreal(scale -50) / 50 * 0.5;
         else if (scale < 50)
             m_fScale =  1- (qreal(50 - scale) / 50 * 1/2);
         else
           m_fScale = 1;
     }

     void GLWidget::setLogo() {
         qtLogo = true;
     }

     void GLWidget::setTexture() {
         qtLogo = false;
     }

     void GLWidget::showBubbles(bool bubbles)
     {
        m_showBubbles = bubbles;
     }

     void GLWidget::paintQtLogo()
     {
         glDisable(GL_TEXTURE_2D);
         glEnableClientState(GL_VERTEX_ARRAY);
         glVertexPointer(3,GL_FLOAT,0, createdVertices);
         glEnableClientState(GL_NORMAL_ARRAY);
         glNormalPointer(GL_FLOAT,0,createdNormals);
         glDrawArrays(GL_TRIANGLES, 0, m_vertexNumber / 3);
     }

     void GLWidget::paintTexturedCube()
     {
         glEnable(GL_TEXTURE_2D);
         glBindTexture(GL_TEXTURE_2D, m_uiTexture);
         GLfloat afVertices[] = {
             -0.5, 0.5, 0.5, 0.5,-0.5,0.5,-0.5,-0.5,0.5,
             0.5, -0.5, 0.5, -0.5,0.5,0.5,0.5,0.5,0.5,
             -0.5, -0.5, -0.5, 0.5,-0.5,-0.5,-0.5,0.5,-0.5,
             0.5, 0.5, -0.5, -0.5,0.5,-0.5,0.5,-0.5,-0.5,

             0.5, -0.5, -0.5, 0.5,-0.5,0.5,0.5,0.5,-0.5,
             0.5, 0.5, 0.5, 0.5,0.5,-0.5,0.5,-0.5,0.5,
             -0.5, 0.5, -0.5, -0.5,-0.5,0.5,-0.5,-0.5,-0.5,
             -0.5, -0.5, 0.5, -0.5,0.5,-0.5,-0.5,0.5,0.5,

             0.5, 0.5,  -0.5, -0.5, 0.5,  0.5,  -0.5,  0.5,  -0.5,
             -0.5,  0.5,  0.5,  0.5,  0.5,  -0.5, 0.5, 0.5,  0.5,
             -0.5,  -0.5, -0.5, -0.5, -0.5, 0.5,  0.5, -0.5, -0.5,
             0.5, -0.5, 0.5,  0.5,  -0.5, -0.5, -0.5,  -0.5, 0.5
         };
         glEnableClientState(GL_VERTEX_ARRAY);
         glVertexPointer(3,GL_FLOAT,0,afVertices);

         GLfloat afTexCoord[] = {
             0.0f,0.0f, 1.0f,1.0f, 1.0f,0.0f,
             1.0f,1.0f, 0.0f,0.0f, 0.0f,1.0f,
             1.0f,1.0f, 1.0f,0.0f, 0.0f,1.0f,
             0.0f,0.0f, 0.0f,1.0f, 1.0f,0.0f,

             1.0f,1.0f, 1.0f,0.0f, 0.0f,1.0f,
             0.0f,0.0f, 0.0f,1.0f, 1.0f,0.0f,
             0.0f,0.0f, 1.0f,1.0f, 1.0f,0.0f,
             1.0f,1.0f, 0.0f,0.0f, 0.0f,1.0f,

             0.0f,1.0f, 1.0f,0.0f, 1.0f,1.0f,
             1.0f,0.0f, 0.0f,1.0f, 0.0f,0.0f,
             1.0f,0.0f, 1.0f,1.0f, 0.0f,0.0f,
             0.0f,1.0f, 0.0f,0.0f, 1.0f,1.0f
         };
         glEnableClientState(GL_TEXTURE_COORD_ARRAY);
         glTexCoordPointer(2,GL_FLOAT,0,afTexCoord);

         GLfloat afNormals[] = {

             0,0,-1, 0,0,-1, 0,0,-1,
             0,0,-1, 0,0,-1, 0,0,-1,
             0,0,1, 0,0,1, 0,0,1,
             0,0,1, 0,0,1, 0,0,1,

             -1,0,0, -1,0,0, -1,0,0,
             -1,0,0, -1,0,0, -1,0,0,
             1,0,0, 1,0,0, 1,0,0,
             1,0,0, 1,0,0, 1,0,0,

             0,-1,0, 0,-1,0, 0,-1,0,
             0,-1,0, 0,-1,0, 0,-1,0,
             0,1,0, 0,1,0, 0,1,0,
             0,1,0, 0,1,0, 0,1,0
         };
         glEnableClientState(GL_NORMAL_ARRAY);
         glNormalPointer(GL_FLOAT,0,afNormals);

         glDrawArrays(GL_TRIANGLES, 0, 36);
     }

     void GLWidget::initializeGL ()
     {
         glClearColor(0.1f, 0.1f, 0.2f, 1.0f);

         glEnable(GL_TEXTURE_2D);
         glGenTextures(1, &m_uiTexture);
         m_uiTexture = bindTexture(QImage(":/qt.png"));

         glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR );
         glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR );
         glEnable(GL_LIGHTING);
         glEnable(GL_LIGHT0);

         GLfloat aLightPosition[] = {0.0f,0.3f,1.0f,0.0f};

         glLightfv(GL_LIGHT0, GL_SPOT_DIRECTION, aLightPosition);
         m_fAngle = 0;
         m_fScale = 1;
         createGeometry();
         createBubbles(bubbleNum - bubbles.count());
     }

     void GLWidget::paintGL()
     {
         createBubbles(bubbleNum - bubbles.count());

         QPainter painter;
         painter.begin(this);

         glMatrixMode(GL_PROJECTION);
         glPushMatrix();
         glLoadIdentity();

         glMatrixMode(GL_MODELVIEW);
         glPushMatrix();
         glMatrixMode(GL_TEXTURE);
         glPushMatrix();

         //Since OpenGL ES does not support glPush/PopAttrib(GL_ALL_ATTRIB_BITS)
         //we have to take care of the states ourselves

         glClearColor(0.1f, 0.1f, 0.2f, 1.0f);
         glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
         glEnable(GL_TEXTURE_2D);

         glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR );
         glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR );
         glEnable(GL_LIGHTING);
         glEnable(GL_LIGHT0);

         glShadeModel(GL_FLAT);
         glFrontFace(GL_CW);
         glCullFace(GL_FRONT);
         glEnable(GL_CULL_FACE);
         glEnable(GL_DEPTH_TEST);

         glMatrixMode(GL_MODELVIEW);
         glLoadIdentity();

         glRotatef(m_fAngle, 0.0f, 1.0f, 0.0f);
         glRotatef(m_fAngle, 1.0f, 0.0f, 0.0f);
         glRotatef(m_fAngle, 0.0f, 0.0f, 1.0f);
         glScalef(m_fScale, m_fScale,m_fScale);
         glTranslatef(0.0f,-0.2f,0.0f);

         GLfloat matDiff[] = {0.40f, 1.0f, 0.0f, 1.0f};
         glMaterialfv(GL_FRONT_AND_BACK, GL_DIFFUSE, matDiff);

         if (qtLogo)
             paintQtLogo();
         else
             paintTexturedCube();

         glMatrixMode(GL_MODELVIEW);
         glPopMatrix();
         glMatrixMode(GL_PROJECTION);
         glPopMatrix();
         glMatrixMode(GL_TEXTURE);
         glPopMatrix();

         glDisable(GL_LIGHTING);
         glDisable(GL_LIGHT0);

         glDisable(GL_DEPTH_TEST);
         glDisable(GL_CULL_FACE);

         if (m_showBubbles)
             foreach (Bubble *bubble, bubbles) {
                 bubble->drawBubble(&painter);
         }

         QString framesPerSecond;
         framesPerSecond.setNum(frames /(time.elapsed() / 1000.0), 'f', 2);

         painter.setPen(Qt::white);

         painter.drawText(20, 40, framesPerSecond + " fps");

         painter.end();

         swapBuffers();

         QMutableListIterator<Bubble*> iter(bubbles);

         while (iter.hasNext()) {
             Bubble *bubble = iter.next();
             bubble->move(rect());
         }
         if (!(frames % 100)) {
             time.start();
             frames = 0;
         }
         m_fAngle += 1.0f;
         frames ++;
     }

     void GLWidget::createBubbles(int number)
     {
         for (int i = 0; i < number; ++i) {
             QPointF position(width()*(0.1 + (0.8*qrand()/(RAND_MAX+1.0))),
                             height()*(0.1 + (0.8*qrand()/(RAND_MAX+1.0))));
             qreal radius = qMin(width(), height())*(0.0175 + 0.0875*qrand()/(RAND_MAX+1.0));
             QPointF velocity(width()*0.0175*(-0.5 + qrand()/(RAND_MAX+1.0)),
                             height()*0.0175*(-0.5 + qrand()/(RAND_MAX+1.0)));

             bubbles.append(new Bubble(position, radius, velocity));
         }
     }

     void GLWidget::createGeometry()
     {
         vertices.clear();
         normals.clear();

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

         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 qreal Pi = 3.14159f;
         const int NumSectors = 100;

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

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

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

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

         m_vertexNumber = vertices.size();
         createdVertices = new GLfloat[m_vertexNumber];
         createdNormals = new GLfloat[m_vertexNumber];
         for (int i = 0;i < m_vertexNumber;i++) {
           createdVertices[i] = vertices.at(i) * 2;
           createdNormals[i] = normals.at(i);
         }
         vertices.clear();
         normals.clear();
     }

     void GLWidget::quad(qreal x1, qreal y1, qreal x2, qreal y2, qreal x3, qreal y3, qreal x4, qreal y4)
     {
         qreal nx, ny, nz;

         vertices << x1 << y1 << -0.05f;
         vertices << x2 << y2 << -0.05f;
         vertices << x4 << y4 << -0.05f;

         vertices << x3 << y3 << -0.05f;
         vertices << x4 << y4 << -0.05f;
         vertices << x2 << y2 << -0.05f;

         CrossProduct(nx, ny, nz, x2 - x1, y2 - y1, 0, x4 - x1, y4 - y1, 0);
         Normalize(nx, ny, nz);

         normals << nx << ny << nz;
         normals << nx << ny << nz;
         normals << nx << ny << nz;

         normals << nx << ny << nz;
         normals << nx << ny << nz;
         normals << nx << ny << nz;

         vertices << x4 << y4 << 0.05f;
         vertices << x2 << y2 << 0.05f;
         vertices << x1 << y1 << 0.05f;

         vertices << x2 << y2 << 0.05f;
         vertices << x4 << y4 << 0.05f;
         vertices << x3 << y3 << 0.05f;

         CrossProduct(nx, ny, nz, x2 - x4, y2 - y4, 0, x1 - x4, y1 - y4, 0);
         Normalize(nx, ny, nz);

         normals << nx << ny << nz;
         normals << nx << ny << nz;
         normals << nx << ny << nz;

         normals << nx << ny << nz;
         normals << nx << ny << nz;
         normals << nx << ny << nz;
     }

     void GLWidget::extrude(qreal x1, qreal y1, qreal x2, qreal y2)
     {
         qreal nx, ny, nz;

         vertices << x1 << y1 << +0.05f;
         vertices << x2 << y2 << +0.05f;
         vertices << x1 << y1 << -0.05f;

         vertices << x2 << y2 << -0.05f;
         vertices << x1 << y1 << -0.05f;
         vertices << x2 << y2 << +0.05f;

         CrossProduct(nx, ny, nz, x2 - x1, y2 - y1, 0.0f, 0.0f, 0.0f, -0.1f);
         Normalize(nx, ny, nz);

         normals << nx << ny << nz;
         normals << nx << ny << nz;
         normals << nx << ny << nz;

         normals << nx << ny << nz;
         normals << nx << ny << nz;
         normals << nx << ny << nz;
     }