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#include "lighting.h"

#include <QtGui>

#ifndef M_PI

#define M_PI 3.14159265358979323846

#endif

Lighting::Lighting(QWidget *parent): QGraphicsView(parent), angle(0.0)

{

    setScene(&m_scene);

    setupScene();

    QTimer *timer = new QTimer(this);

    connect(timer, SIGNAL(timeout()), SLOT(animate()));

    timer->setInterval(30);

    timer->start();

    setRenderHint(QPainter::Antialiasing, true);

    setFrameStyle(QFrame::NoFrame);

}

void Lighting::setupScene()

{

    m_scene.setSceneRect(-300, -200, 600, 460);

    QLinearGradient linearGrad(QPointF(-100, -100), QPointF(100, 100));

    linearGrad.setColorAt(0, QColor(255, 255, 255));

    linearGrad.setColorAt(1, QColor(192, 192, 255));

    setBackgroundBrush(linearGrad);

    QRadialGradient radialGrad(30, 30, 30);

    radialGrad.setColorAt(0, Qt::yellow);

    radialGrad.setColorAt(0.2, Qt::yellow);

    radialGrad.setColorAt(1, Qt::transparent);

    QPixmap pixmap(60, 60);

    pixmap.fill(Qt::transparent);

    QPainter painter(&pixmap);

    painter.setPen(Qt::NoPen);

    painter.setBrush(radialGrad);

    painter.drawEllipse(0, 0, 60, 60);

    painter.end();

    m_lightSource = m_scene.addPixmap(pixmap);

    m_lightSource->setZValue(2);

    for (int i = -2; i < 3; ++i)

        for (int j = -2; j < 3; ++j) {

            QAbstractGraphicsShapeItem *item;

            if ((i + j) & 1)

                item = new QGraphicsEllipseItem(0, 0, 50, 50);

            else

                item = new QGraphicsRectItem(0, 0, 50, 50);

            item->setPen(QPen(Qt::black, 1));

            item->setBrush(QBrush(Qt::white));

            QGraphicsDropShadowEffect *effect = new QGraphicsDropShadowEffect;

            effect->setBlurRadius(8);

            item->setGraphicsEffect(effect);

            item->setZValue(1);

            item->setPos(i * 80, j * 80);

            m_scene.addItem(item);

            m_items << item;

        }

}

void Lighting::animate()

{

    angle += (M_PI / 30);

    qreal xs = 200 * sin(angle) - 40 + 25;

    qreal ys = 200 * cos(angle) - 40 + 25;

    m_lightSource->setPos(xs, ys);

    for (int i = 0; i < m_items.size(); ++i) {

        QGraphicsItem *item = m_items.at(i);

        Q_ASSERT(item);

        QGraphicsDropShadowEffect *effect = static_cast<QGraphicsDropShadowEffect *>(item->graphicsEffect());

        Q_ASSERT(effect);

        QPointF delta(item->x() - xs, item->y() - ys);

        effect->setOffset(delta.toPoint() / 30);

        qreal dx = delta.x();

        qreal dy = delta.y();

        qreal dd = sqrt(dx * dx + dy * dy);

        QColor color = effect->color();

        color.setAlphaF(qBound(0.4, 1 - dd / 200.0, 0.7));

        effect->setColor(color);

    }

    m_scene.update();

}