lighting.cpp Example File

/****************************************************************************
**
** Copyright (C) 2016 The Qt Company Ltd.
** Contact: https://www.qt.io/licensing/
**
** This file is part of the examples of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:BSD$
** Commercial License Usage
** Licensees holding valid commercial Qt licenses may use this file in
** accordance with the commercial license agreement provided with the
** Software or, alternatively, in accordance with the terms contained in
** a written agreement between you and The Qt Company. For licensing terms
** and conditions see https://www.qt.io/terms-conditions. For further
** information use the contact form at https://www.qt.io/contact-us.
**
** BSD License Usage
** Alternatively, you may use this file under the terms of the BSD license
** as follows:
**
** "Redistribution and use in source and binary forms, with or without
** modification, are permitted provided that the following conditions are
** met:
**   * Redistributions of source code must retain the above copyright
**     notice, this list of conditions and the following disclaimer.
**   * Redistributions in binary form must reproduce the above copyright
**     notice, this list of conditions and the following disclaimer in
**     the documentation and/or other materials provided with the
**     distribution.
**   * Neither the name of The Qt Company Ltd nor the names of its
**     contributors may be used to endorse or promote products derived
**     from this software without specific prior written permission.
**
**
** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
** A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
** OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
** LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
** DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
** OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE."
**
** $QT_END_LICENSE$
**
****************************************************************************/
#include "lighting.h"
#include <QtWidgets>
#include <QtCore/qmath.h>
#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 * qSin(angle) - 40 + 25;
    qreal ys = 200 * qCos(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 = qSqrt(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();
}
void Lighting::resizeEvent(QResizeEvent * /* event */)
{
}