stickman.cpp Example File
animation/stickman/stickman.cpp

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 #include "stickman.h"
 #include "node.h"

 #include <QPainter>
 #include <QTimer>

 #define _USE_MATH_DEFINES
 #include <math.h>

 #ifndef M_PI
 #define M_PI 3.14159265358979323846
 #endif

 static const qreal Coords[NodeCount * 2] = {
     0.0, -150.0, // head, #0

     0.0, -100.0, // body pentagon, top->bottom, left->right, #1 - 5
     -50.0, -50.0,
     50.0, -50.0,
     -25.0, 50.0,
     25.0, 50.0,

     -100.0, 0.0, // right arm, #6 - 7
     -125.0, 50.0,

     100.0, 0.0, // left arm, #8 - 9
     125.0, 50.0,

     -35.0, 75.0, // lower body, #10 - 11
     35.0, 75.0,

     -25.0, 200.0, // right leg, #12 - 13
     -30.0, 300.0,

     25.0, 200.0, // left leg, #14 - 15
     30.0, 300.0

 };

 static const int Bones[BoneCount * 2] = {
     0, 1, // neck

     1, 2, // body
     1, 3,
     1, 4,
     1, 5,
     2, 3,
     2, 4,
     2, 5,
     3, 4,
     3, 5,
     4, 5,

     2, 6, // right arm
     6, 7,

     3, 8, // left arm
     8, 9,

     4, 10, // lower body
     4, 11,
     5, 10,
     5, 11,
     10, 11,

     10, 12, // right leg
     12, 13,

     11, 14, // left leg
     14, 15

 };

 StickMan::StickMan()
 {
     m_sticks = true;
     m_isDead = false;
     m_pixmap = QPixmap("images/head.png");
     m_penColor = Qt::white;
     m_fillColor = Qt::black;

     // Set up start position of limbs
     for (int i=0; i<NodeCount; ++i) {
         m_nodes[i] = new Node(QPointF(Coords[i * 2], Coords[i * 2 + 1]), this);
         connect(m_nodes[i], SIGNAL(positionChanged()), this, SLOT(childPositionChanged()));
     }

     for (int i=0; i<BoneCount; ++i) {
         int n1 = Bones[i * 2];
         int n2 = Bones[i * 2 + 1];

         Node *node1 = m_nodes[n1];
         Node *node2 = m_nodes[n2];

         QPointF dist = node1->pos() - node2->pos();
         m_perfectBoneLengths[i] = sqrt(pow(dist.x(),2) + pow(dist.y(),2));
     }

     startTimer(10);
 }

 StickMan::~StickMan()
 {
 }

 void StickMan::childPositionChanged()
 {
     prepareGeometryChange();
 }

 void StickMan::setDrawSticks(bool on)
 {
     m_sticks = on;
     for (int i=0;i<nodeCount();++i) {
         Node *node = m_nodes[i];
         node->setVisible(on);
     }
 }

 QRectF StickMan::boundingRect() const
 {
     // account for head radius=50.0 plus pen which is 5.0
     return childrenBoundingRect().adjusted(-55.0, -55.0, 55.0, 55.0);
 }

 int StickMan::nodeCount() const
 {
     return NodeCount;
 }

 Node *StickMan::node(int idx) const
 {
     if (idx >= 0 && idx < NodeCount)
         return m_nodes[idx];
     else
         return 0;
 }

 void StickMan::timerEvent(QTimerEvent *)
 {
     update();
 }

 void StickMan::stabilize()
 {
     static const qreal threshold = 0.001;

     for (int i=0; i<BoneCount; ++i) {
         int n1 = Bones[i * 2];
         int n2 = Bones[i * 2 + 1];

         Node *node1 = m_nodes[n1];
         Node *node2 = m_nodes[n2];

         QPointF pos1 = node1->pos();
         QPointF pos2 = node2->pos();

         QPointF dist = pos1 - pos2;
         qreal length = sqrt(pow(dist.x(),2) + pow(dist.y(),2));
         qreal diff = (length - m_perfectBoneLengths[i]) / length;

         QPointF p = dist * (0.5 * diff);
         if (p.x() > threshold && p.y() > threshold) {
             pos1 -= p;
             pos2 += p;

             node1->setPos(pos1);
             node2->setPos(pos2);
         }
     }
 }

 QPointF StickMan::posFor(int idx) const
 {
     return m_nodes[idx]->pos();
 }

 //#include <QTime>
 void StickMan::paint(QPainter *painter, const QStyleOptionGraphicsItem *, QWidget *)
 {
   /*  static int frames = 0;
     static QTime time;
     if (frames++ % 100 == 0) {
         frames = 1;
         time.restart();
     }

     if (time.elapsed() > 0) {
         painter->setPen(Qt::white);
         painter->drawText(0, 0, QString::number(frames / (time.elapsed() / 1000.0)));
     }*/

     stabilize();
     if (m_sticks) {
         painter->setPen(Qt::white);
         for (int i=0; i<BoneCount; ++i) {
             int n1 = Bones[i * 2];
             int n2 = Bones[i * 2 + 1];

             Node *node1 = m_nodes[n1];
             Node *node2 = m_nodes[n2];

             painter->drawLine(node1->pos(), node2->pos());
         }
     } else {
         // first bone is neck and will be used for head

         QPainterPath path;
         path.moveTo(posFor(0));
         path.lineTo(posFor(1));

         // right arm
         path.lineTo(posFor(2));
         path.lineTo(posFor(6));
         path.lineTo(posFor(7));

         // left arm
         path.moveTo(posFor(3));
         path.lineTo(posFor(8));
         path.lineTo(posFor(9));

         // body
         path.moveTo(posFor(2));
         path.lineTo(posFor(4));
         path.lineTo(posFor(10));
         path.lineTo(posFor(11));
         path.lineTo(posFor(5));
         path.lineTo(posFor(3));
         path.lineTo(posFor(1));

         // right leg
         path.moveTo(posFor(10));
         path.lineTo(posFor(12));
         path.lineTo(posFor(13));

         // left leg
         path.moveTo(posFor(11));
         path.lineTo(posFor(14));
         path.lineTo(posFor(15));

         painter->setPen(QPen(m_penColor, 5.0, Qt::SolidLine, Qt::RoundCap));
         painter->drawPath(path);

         {
             int n1 = Bones[0];
             int n2 = Bones[1];
             Node *node1 = m_nodes[n1];
             Node *node2 = m_nodes[n2];

             QPointF dist = node2->pos() - node1->pos();

             qreal sinAngle = dist.x() / sqrt(pow(dist.x(), 2) + pow(dist.y(), 2));
             qreal angle = asin(sinAngle) * 180.0 / M_PI;

             QPointF headPos = node1->pos();
             painter->translate(headPos);
             painter->rotate(-angle);

             painter->setBrush(m_fillColor);
             painter->drawEllipse(QPointF(0,0), 50.0, 50.0);

             painter->setBrush(m_penColor);
             painter->setPen(QPen(m_penColor, 2.5, Qt::SolidLine, Qt::RoundCap));

             // eyes
             if (m_isDead) {
                 painter->drawLine(-30.0, -30.0, -20.0, -20.0);
                 painter->drawLine(-20.0, -30.0, -30.0, -20.0);

                 painter->drawLine(20.0, -30.0, 30.0, -20.0);
                 painter->drawLine(30.0, -30.0, 20.0, -20.0);
             } else {
                 painter->drawChord(QRectF(-30.0, -30.0, 25.0, 70.0), 30.0*16, 120.0*16);
                 painter->drawChord(QRectF(5.0, -30.0, 25.0, 70.0), 30.0*16, 120.0*16);
             }

             // mouth
             if (m_isDead) {
                 painter->drawLine(-28.0, 2.0, 29.0, 2.0);
             } else {
                 painter->setBrush(QColor(128, 0, 64 ));
                 painter->drawChord(QRectF(-28.0, 2.0-55.0/2.0, 57.0, 55.0), 0.0, -180.0*16);
             }

             // pupils
             if (!m_isDead) {
                 painter->setPen(QPen(m_fillColor, 1.0, Qt::SolidLine, Qt::RoundCap));
                 painter->setBrush(m_fillColor);
                 painter->drawEllipse(QPointF(-12.0, -25.0), 5.0, 5.0);
                 painter->drawEllipse(QPointF(22.0, -25.0), 5.0, 5.0);
             }
         }
     }
 }