Colliding Mice Example | Qt Widgets 5.13.0

Qt 5.13 | Qt Widgets | Colliding Mice Example

Qt 5.13.0 Reference Documentation

# Colliding Mice Example

      /****************************************************************************
      **
      ** 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 "mouse.h"

      #include <QGraphicsScene>
      #include <QPainter>
      #include <QRandomGenerator>
      #include <QStyleOption>
      #include <qmath.h>

      const qreal Pi = M_PI;
      const qreal TwoPi = 2 * M_PI;

      static qreal normalizeAngle(qreal angle)
      {
          while (angle < 0)
              angle += TwoPi;
          while (angle > TwoPi)
              angle -= TwoPi;
          return angle;
      }

      Mouse::Mouse()
          : angle(0), speed(0), mouseEyeDirection(0),
            color(QRandomGenerator::global()->bounded(256), QRandomGenerator::global()->bounded(256), QRandomGenerator::global()->bounded(256))
      {
          setRotation(QRandomGenerator::global()->bounded(360 * 16));
      }

      QRectF Mouse::boundingRect() const
      {
          qreal adjust = 0.5;
          return QRectF(-18 - adjust, -22 - adjust,
                        36 + adjust, 60 + adjust);
      }

      QPainterPath Mouse::shape() const
      {
          QPainterPath path;
          path.addRect(-10, -20, 20, 40);
          return path;
      }

      void Mouse::paint(QPainter *painter, const QStyleOptionGraphicsItem *, QWidget *)
      {
          // Body
          painter->setBrush(color);
          painter->drawEllipse(-10, -20, 20, 40);

          // Eyes
          painter->setBrush(Qt::white);
          painter->drawEllipse(-10, -17, 8, 8);
          painter->drawEllipse(2, -17, 8, 8);

          // Nose
          painter->setBrush(Qt::black);
          painter->drawEllipse(QRectF(-2, -22, 4, 4));

          // Pupils
          painter->drawEllipse(QRectF(-8.0 + mouseEyeDirection, -17, 4, 4));
          painter->drawEllipse(QRectF(4.0 + mouseEyeDirection, -17, 4, 4));

          // Ears
          painter->setBrush(scene()->collidingItems(this).isEmpty() ? Qt::darkYellow : Qt::red);
          painter->drawEllipse(-17, -12, 16, 16);
          painter->drawEllipse(1, -12, 16, 16);

          // Tail
          QPainterPath path(QPointF(0, 20));
          path.cubicTo(-5, 22, -5, 22, 0, 25);
          path.cubicTo(5, 27, 5, 32, 0, 30);
          path.cubicTo(-5, 32, -5, 42, 0, 35);
          painter->setBrush(Qt::NoBrush);
          painter->drawPath(path);
      }

      void Mouse::advance(int step)
      {
          if (!step)
              return;
          // Don't move too far away
          QLineF lineToCenter(QPointF(0, 0), mapFromScene(0, 0));
          if (lineToCenter.length() > 150) {
              qreal angleToCenter = std::atan2(lineToCenter.dy(), lineToCenter.dx());
              angleToCenter = normalizeAngle((Pi - angleToCenter) + Pi / 2);

              if (angleToCenter < Pi && angleToCenter > Pi / 4) {
                  // Rotate left
                  angle += (angle < -Pi / 2) ? 0.25 : -0.25;
              } else if (angleToCenter >= Pi && angleToCenter < (Pi + Pi / 2 + Pi / 4)) {
                  // Rotate right
                  angle += (angle < Pi / 2) ? 0.25 : -0.25;
              }
          } else if (::sin(angle) < 0) {
              angle += 0.25;
          } else if (::sin(angle) > 0) {
              angle -= 0.25;
          }

          // Try not to crash with any other mice
          const QList<QGraphicsItem *> dangerMice = scene()->items(QPolygonF()
                                 << mapToScene(0, 0)
                                 << mapToScene(-30, -50)
                                 << mapToScene(30, -50));

          for (const QGraphicsItem *item : dangerMice) {
              if (item == this)
                  continue;

              QLineF lineToMouse(QPointF(0, 0), mapFromItem(item, 0, 0));
              qreal angleToMouse = std::atan2(lineToMouse.dy(), lineToMouse.dx());
              angleToMouse = normalizeAngle((Pi - angleToMouse) + Pi / 2);

              if (angleToMouse >= 0 && angleToMouse < Pi / 2) {
                  // Rotate right
                  angle += 0.5;
              } else if (angleToMouse <= TwoPi && angleToMouse > (TwoPi - Pi / 2)) {
                  // Rotate left
                  angle -= 0.5;
              }
          }

          // Add some random movement
          if (dangerMice.size() > 1 && QRandomGenerator::global()->bounded(10) == 0) {
              if (QRandomGenerator::global()->bounded(1))
                  angle += QRandomGenerator::global()->bounded(1 / 500.0);
              else
                  angle -= QRandomGenerator::global()->bounded(1 / 500.0);
          }

          speed += (-50 + QRandomGenerator::global()->bounded(100)) / 100.0;

          qreal dx = ::sin(angle) * 10;
          mouseEyeDirection = (qAbs(dx / 5) < 1) ? 0 : dx / 5;

          setRotation(rotation() + dx);
          setPos(mapToParent(0, -(3 + sin(speed) * 3)));
      }