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#include <QtGui/QImage>

#include "glwidget.h"

#include <math.h>

#ifndef GL_MULTISAMPLE

#define GL_MULTISAMPLE  0x809D

#endif

GLWidget::GLWidget(QWidget *parent)

    : QGLWidget(QGLFormat(QGL::SampleBuffers|QGL::AlphaChannel), parent)

{

    setWindowTitle(tr("OpenGL framebuffer objects"));

    makeCurrent();

    if (QGLFramebufferObject::hasOpenGLFramebufferBlit()) {

        QGLFramebufferObjectFormat format;

        format.setSamples(4);

        format.setAttachment(QGLFramebufferObject::CombinedDepthStencil);

        render_fbo = new QGLFramebufferObject(512, 512, format);

        texture_fbo = new QGLFramebufferObject(512, 512);

    } else {

        render_fbo = new QGLFramebufferObject(1024, 1024);

        texture_fbo = render_fbo;

    }

    rot_x = rot_y = rot_z = 0.0f;

    scale = 0.1f;

    anim = new QTimeLine(750, this);

    anim->setUpdateInterval(20);

    connect(anim, SIGNAL(valueChanged(qreal)), SLOT(animate(qreal)));

    connect(anim, SIGNAL(finished()), SLOT(animFinished()));

    svg_renderer = new QSvgRenderer(QLatin1String(":/res/bubbles.svg"), this);

    connect(svg_renderer, SIGNAL(repaintNeeded()), this, SLOT(draw()));

    logo = QImage(":/res/designer.png");

    logo = logo.convertToFormat(QImage::Format_ARGB32);

    tile_list = glGenLists(1);

    glNewList(tile_list, GL_COMPILE);

    glBegin(GL_QUADS);

    {

        glTexCoord2f(0.0f, 0.0f); glVertex3f(-1.0f, -1.0f,  1.0f);

        glTexCoord2f(1.0f, 0.0f); glVertex3f( 1.0f, -1.0f,  1.0f);

        glTexCoord2f(1.0f, 1.0f); glVertex3f( 1.0f,  1.0f,  1.0f);

        glTexCoord2f(0.0f, 1.0f); glVertex3f(-1.0f,  1.0f,  1.0f);

        glTexCoord2f(1.0f, 0.0f); glVertex3f(-1.0f, -1.0f, -1.0f);

        glTexCoord2f(1.0f, 1.0f); glVertex3f(-1.0f,  1.0f, -1.0f);

        glTexCoord2f(0.0f, 1.0f); glVertex3f( 1.0f,  1.0f, -1.0f);

        glTexCoord2f(0.0f, 0.0f); glVertex3f( 1.0f, -1.0f, -1.0f);

        glTexCoord2f(0.0f, 1.0f); glVertex3f(-1.0f,  1.0f, -1.0f);

        glTexCoord2f(0.0f, 0.0f); glVertex3f(-1.0f,  1.0f,  1.0f);

        glTexCoord2f(1.0f, 0.0f); glVertex3f( 1.0f,  1.0f,  1.0f);

        glTexCoord2f(1.0f, 1.0f); glVertex3f( 1.0f,  1.0f, -1.0f);

        glTexCoord2f(1.0f, 1.0f); glVertex3f(-1.0f, -1.0f, -1.0f);

        glTexCoord2f(0.0f, 1.0f); glVertex3f( 1.0f, -1.0f, -1.0f);

        glTexCoord2f(0.0f, 0.0f); glVertex3f( 1.0f, -1.0f,  1.0f);

        glTexCoord2f(1.0f, 0.0f); glVertex3f(-1.0f, -1.0f,  1.0f);

        glTexCoord2f(1.0f, 0.0f); glVertex3f( 1.0f, -1.0f, -1.0f);

        glTexCoord2f(1.0f, 1.0f); glVertex3f( 1.0f,  1.0f, -1.0f);

        glTexCoord2f(0.0f, 1.0f); glVertex3f( 1.0f,  1.0f,  1.0f);

        glTexCoord2f(0.0f, 0.0f); glVertex3f( 1.0f, -1.0f,  1.0f);

        glTexCoord2f(0.0f, 0.0f); glVertex3f(-1.0f, -1.0f, -1.0f);

        glTexCoord2f(1.0f, 0.0f); glVertex3f(-1.0f, -1.0f,  1.0f);

        glTexCoord2f(1.0f, 1.0f); glVertex3f(-1.0f,  1.0f,  1.0f);

        glTexCoord2f(0.0f, 1.0f); glVertex3f(-1.0f,  1.0f, -1.0f);

    }

    glEnd();

    glEndList();

    wave = new GLfloat[logo.width()*logo.height()];

    memset(wave, 0, logo.width()*logo.height());

    startTimer(30); // wave timer

}

GLWidget::~GLWidget()

{

    delete[] wave;

    glDeleteLists(tile_list, 1);

    delete texture_fbo;

    if (render_fbo != texture_fbo)

        delete render_fbo;

}

void GLWidget::paintEvent(QPaintEvent *)

{

    draw();

}

void GLWidget::draw()

{

    QPainter p(this); // used for text overlay

    // save the GL state set for QPainter

    saveGLState();

    // render the 'bubbles.svg' file into our framebuffer object

    QPainter fbo_painter(render_fbo);

    svg_renderer->render(&fbo_painter);

    fbo_painter.end();

    if (render_fbo != texture_fbo) {

        QRect rect(0, 0, render_fbo->width(), render_fbo->height());

        QGLFramebufferObject::blitFramebuffer(texture_fbo, rect,

                                              render_fbo, rect);

    }

    // draw into the GL widget

    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

    glMatrixMode(GL_PROJECTION);

    glLoadIdentity();

    glFrustum(-1, 1, -1, 1, 10, 100);

    glTranslatef(0.0f, 0.0f, -15.0f);

    glMatrixMode(GL_MODELVIEW);

    glLoadIdentity();

    glViewport(0, 0, width(), height());

    glEnable(GL_BLEND);

    glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);

    glBindTexture(GL_TEXTURE_2D, texture_fbo->texture());

    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);

    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);

    glEnable(GL_TEXTURE_2D);

    glEnable(GL_MULTISAMPLE);

    glEnable(GL_CULL_FACE);

    // draw background

    glPushMatrix();

    glScalef(1.7f, 1.7f, 1.7f);

    glColor4f(1.0f, 1.0f, 1.0f, 1.0f);

    glCallList(tile_list);

    glPopMatrix();

    const int w = logo.width();

    const int h = logo.height();

    glRotatef(rot_x, 1.0f, 0.0f, 0.0f);

    glRotatef(rot_y, 0.0f, 1.0f, 0.0f);

    glRotatef(rot_z, 0.0f, 0.0f, 1.0f);

    glScalef(scale/w, scale/w, scale/w);

    glDepthFunc(GL_LESS);

    glEnable(GL_DEPTH_TEST);

    // draw the Qt icon

    glTranslatef(-w+1, -h+1, 0.0f);

    for (int y=h-1; y>=0; --y) {

        uint *p = (uint*) logo.scanLine(y);

        uint *end = p + w;

        int  x = 0;

        while (p < end) {

            glColor4ub(qRed(*p), qGreen(*p), qBlue(*p), uchar(qAlpha(*p)*.9));

            glTranslatef(0.0f, 0.0f, wave[y*w+x]);

            if (qAlpha(*p) > 128)

                glCallList(tile_list);

            glTranslatef(0.0f, 0.0f, -wave[y*w+x]);

            glTranslatef(2.0f, 0.0f, 0.0f);

            ++x;

            ++p;

        }

        glTranslatef(-w*2.0f, 2.0f, 0.0f);

    }

    // restore the GL state that QPainter expects

    restoreGLState();

    // draw the overlayed text using QPainter

    p.setPen(QColor(197, 197, 197, 157));

    p.setBrush(QColor(197, 197, 197, 127));

    p.drawRect(QRect(0, 0, width(), 50));

    p.setPen(Qt::black);

    p.setBrush(Qt::NoBrush);

    const QString str1(tr("A simple OpenGL framebuffer object example."));

    const QString str2(tr("Use the mouse wheel to zoom, press buttons and move mouse to rotate, double-click to flip."));

    QFontMetrics fm(p.font());

    p.drawText(width()/2 - fm.width(str1)/2, 20, str1);

    p.drawText(width()/2 - fm.width(str2)/2, 20 + fm.lineSpacing(), str2);

}

void GLWidget::mousePressEvent(QMouseEvent *e)

{

    anchor = e->pos();

}

void GLWidget::mouseMoveEvent(QMouseEvent *e)

{

    QPoint diff = e->pos() - anchor;

    if (e->buttons() & Qt::LeftButton) {

        rot_x += diff.y()/5.0f;

        rot_y += diff.x()/5.0f;

    } else if (e->buttons() & Qt::RightButton) {

        rot_z += diff.x()/5.0f;

    }

    anchor = e->pos();

    draw();

}

void GLWidget::wheelEvent(QWheelEvent *e)

{

    e->delta() > 0 ? scale += scale*0.1f : scale -= scale*0.1f;

    draw();

}

void GLWidget::mouseDoubleClickEvent(QMouseEvent *)

{

    anim->start();

}

void GLWidget::animate(qreal val)

{

    rot_y = val * 180;

    draw();

}

void GLWidget::animFinished()

{

    if (anim->direction() == QTimeLine::Forward)

        anim->setDirection(QTimeLine::Backward);

    else

        anim->setDirection(QTimeLine::Forward);

}

void GLWidget::saveGLState()

{

    glPushAttrib(GL_ALL_ATTRIB_BITS);

    glMatrixMode(GL_PROJECTION);

    glPushMatrix();

    glMatrixMode(GL_MODELVIEW);

    glPushMatrix();

}

void GLWidget::restoreGLState()

{

    glMatrixMode(GL_PROJECTION);

    glPopMatrix();

    glMatrixMode(GL_MODELVIEW);

    glPopMatrix();

    glPopAttrib();

}

#define PI 3.14159

void GLWidget::timerEvent(QTimerEvent *)

{

    if (QApplication::mouseButtons() != 0)

        return;

    static bool scale_in = true;

    if (scale_in && scale > 35.0f)

        scale_in = false;

    else if (!scale_in && scale < .5f)

        scale_in = true;

    scale = scale_in ? scale + scale*0.01f : scale-scale*0.01f;

    rot_z += 0.3f;

    rot_x += 0.1f;

    int dx, dy; // disturbance point

    float s, v, W, t;

    int i, j;

    static float wt[128][128];

    const int width = logo.width();

    const int AMP = 5;

    dx = dy = width >> 1;

    W = .3f;

    v = -4; // wave speed

    for (i = 0; i < width; ++i) {

	for ( j = 0; j < width; ++j) {

	    s = sqrt((double) ((j - dx) * (j - dx) + (i - dy) * (i - dy)));

	    wt[i][j] += 0.1f;

	    t = s / v;

            if (s != 0)

                wave[i*width + j] = AMP * sin(2 * PI * W * (wt[i][j] + t)) / (0.2*(s + 2));

            else

                wave[i*width + j] = AMP * sin(2 * PI * W * (wt[i][j] + t));

	}

    }

}