glwidget.cpp Example File

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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;
 }