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** This file is part of the examples of the Qt Toolkit.
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#include "glwidget.h"
#include <QPainter>
#include <QPaintEngine>
#include <math.h>

#include "bubble.h"


const int bubbleNum = 8;

GLWidget::GLWidget(QWidget *parent)
    : QGLWidget(parent)
{
    qtLogo = true;
    frames = 0;
    setAttribute(Qt::WA_PaintOnScreen);
    setAttribute(Qt::WA_NoSystemBackground);
    setAutoBufferSwap(false);
    m_showBubbles = true;
#ifndef Q_WS_QWS
    setMinimumSize(300, 250);
#endif
}

GLWidget::~GLWidget()
{
}

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);
    program1.setAttributeArray(vertexAttr1, vertices.constData());
    program1.setAttributeArray(normalAttr1, normals.constData());
    glDrawArrays(GL_TRIANGLES, 0, vertices.size());
    program1.disableAttributeArray(normalAttr1);
    program1.disableAttributeArray(vertexAttr1);
}

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
    };
    program2.setAttributeArray(vertexAttr2, afVertices, 3);

    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
    };
    program2.setAttributeArray(texCoordAttr2, afTexCoord, 2);

    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
    };
    program2.setAttributeArray(normalAttr2, afNormals, 3);

    program2.setUniformValue(textureUniform2, 0);    // use texture unit 0

    glDrawArrays(GL_TRIANGLES, 0, 36);

    program2.disableAttributeArray(vertexAttr2);
    program2.disableAttributeArray(normalAttr2);
    program2.disableAttributeArray(texCoordAttr2);
}

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"));

    QGLShader *vshader1 = new QGLShader(QGLShader::VertexShader, this);
    const char *vsrc1 =
        "attribute highp vec4 vertex;\n"
        "attribute mediump vec3 normal;\n"
        "uniform mediump mat4 matrix;\n"
        "varying mediump vec4 color;\n"
        "void main(void)\n"
        "{\n"
        "    vec3 toLight = normalize(vec3(0.0, 0.3, 1.0));\n"
        "    float angle = max(dot(normal, toLight), 0.0);\n"
        "    vec3 col = vec3(0.40, 1.0, 0.0);\n"
        "    color = vec4(col * 0.2 + col * 0.8 * angle, 1.0);\n"
        "    color = clamp(color, 0.0, 1.0);\n"
        "    gl_Position = matrix * vertex;\n"
        "}\n";
    vshader1->compile(vsrc1);

    QGLShader *fshader1 = new QGLShader(QGLShader::FragmentShader, this);
    const char *fsrc1 =
        "varying mediump vec4 color;\n"
        "void main(void)\n"
        "{\n"
        "    gl_FragColor = color;\n"
        "}\n";
    fshader1->compile(fsrc1);

    program1.addShader(vshader1);
    program1.addShader(fshader1);
    program1.link();

    vertexAttr1 = program1.attributeLocation("vertex");
    normalAttr1 = program1.attributeLocation("normal");
    matrixUniform1 = program1.uniformLocation("matrix");

    QGLShader *vshader2 = new QGLShader(QGLShader::VertexShader);
    const char *vsrc2 =
        "attribute highp vec4 vertex;\n"
        "attribute highp vec4 texCoord;\n"
        "attribute mediump vec3 normal;\n"
        "uniform mediump mat4 matrix;\n"
        "varying highp vec4 texc;\n"
        "varying mediump float angle;\n"
        "void main(void)\n"
        "{\n"
        "    vec3 toLight = normalize(vec3(0.0, 0.3, 1.0));\n"
        "    angle = max(dot(normal, toLight), 0.0);\n"
        "    gl_Position = matrix * vertex;\n"
        "    texc = texCoord;\n"
        "}\n";
    vshader2->compile(vsrc2);

    QGLShader *fshader2 = new QGLShader(QGLShader::FragmentShader);
    const char *fsrc2 =
        "varying highp vec4 texc;\n"
        "uniform sampler2D tex;\n"
        "varying mediump float angle;\n"
        "void main(void)\n"
        "{\n"
        "    highp vec3 color = texture2D(tex, texc.st).rgb;\n"
        "    color = color * 0.2 + color * 0.8 * angle;\n"
        "    gl_FragColor = vec4(clamp(color, 0.0, 1.0), 1.0);\n"
        "}\n";
    fshader2->compile(fsrc2);

    program2.addShader(vshader2);
    program2.addShader(fshader2);
    program2.link();

    vertexAttr2 = program2.attributeLocation("vertex");
    normalAttr2 = program2.attributeLocation("normal");
    texCoordAttr2 = program2.attributeLocation("texCoord");
    matrixUniform2 = program2.uniformLocation("matrix");
    textureUniform2 = program2.uniformLocation("tex");

    glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR );
    glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR );

    m_fAngle = 0;
    m_fScale = 1;
    createGeometry();
    createBubbles(bubbleNum - bubbles.count());
}

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

    QPainter painter;
    painter.begin(this);

    painter.paintEngine()->syncState();

    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 );

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

    QMatrix4x4 modelview;
    modelview.rotate(m_fAngle, 0.0f, 1.0f, 0.0f);
    modelview.rotate(m_fAngle, 1.0f, 0.0f, 0.0f);
    modelview.rotate(m_fAngle, 0.0f, 0.0f, 1.0f);
    modelview.scale(m_fScale);
    modelview.translate(0.0f, -0.2f, 0.0f);

    if (qtLogo) {
        program1.enable();
        program1.setUniformValue(matrixUniform1, modelview);
        paintQtLogo();
        program1.disable();
    } else {
        program2.enable();
        program1.setUniformValue(matrixUniform2, modelview);
        paintTexturedCube();
        program2.disable();
    }

    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);
    }

    for (int i = 0;i < vertices.size();i++)
        vertices[i] *= 2.0f;
}

void GLWidget::quad(qreal x1, qreal y1, qreal x2, qreal y2, qreal x3, qreal y3, qreal x4, qreal y4)
{
    vertices << QVector3D(x1, y1, -0.05f);
    vertices << QVector3D(x2, y2, -0.05f);
    vertices << QVector3D(x4, y4, -0.05f);

    vertices << QVector3D(x3, y3, -0.05f);
    vertices << QVector3D(x4, y4, -0.05f);
    vertices << QVector3D(x2, y2, -0.05f);

    QVector3D n = QVector3D::normal
        (QVector3D(x2 - x1, y2 - y1, 0.0f), QVector3D(x4 - x1, y4 - y1, 0.0f));

    normals << n;
    normals << n;
    normals << n;

    normals << n;
    normals << n;
    normals << n;

    vertices << QVector3D(x4, y4, 0.05f);
    vertices << QVector3D(x2, y2, 0.05f);
    vertices << QVector3D(x1, y1, 0.05f);

    vertices << QVector3D(x2, y2, 0.05f);
    vertices << QVector3D(x4, y4, 0.05f);
    vertices << QVector3D(x3, y3, 0.05f);

    n = QVector3D::normal
        (QVector3D(x2 - x4, y2 - y4, 0.0f), QVector3D(x1 - x4, y1 - y4, 0.0f));

    normals << n;
    normals << n;
    normals << n;

    normals << n;
    normals << n;
    normals << n;
}

void GLWidget::extrude(qreal x1, qreal y1, qreal x2, qreal y2)
{
    vertices << QVector3D(x1, y1, +0.05f);
    vertices << QVector3D(x2, y2, +0.05f);
    vertices << QVector3D(x1, y1, -0.05f);

    vertices << QVector3D(x2, y2, -0.05f);
    vertices << QVector3D(x1, y1, -0.05f);
    vertices << QVector3D(x2, y2, +0.05f);

    QVector3D n = QVector3D::normal
        (QVector3D(x2 - x1, y2 - y1, 0.0f), QVector3D(0.0f, 0.0f, -0.1f));

    normals << n;
    normals << n;
    normals << n;

    normals << n;
    normals << n;
    normals << n;
}