Qt 5.7 | Qt Data Visualization | Rotations Example | scatterdatamodifier.cpp Example File

Qt 5.7.1 Reference Documentation

# scatterdatamodifier.cpp Example File

rotations/scatterdatamodifier.cpp

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      #include "scatterdatamodifier.h"
      #include <QtDataVisualization/qscatterdataproxy.h>
      #include <QtDataVisualization/qvalue3daxis.h>
      #include <QtDataVisualization/q3dscene.h>
      #include <QtDataVisualization/q3dcamera.h>
      #include <QtDataVisualization/qscatter3dseries.h>
      #include <QtDataVisualization/q3dtheme.h>
      #include <QtDataVisualization/QCustom3DItem>
      #include <QtCore/qmath.h>

      using namespace QtDataVisualization;

      static const float verticalRange = 8.0f;
      static const float horizontalRange = verticalRange;
      static const float ellipse_a = horizontalRange / 3.0f;
      static const float ellipse_b = verticalRange;
      static const float doublePi = float(M_PI) * 2.0f;
      static const float radiansToDegrees = 360.0f / doublePi;
      static const float animationFrames = 30.0f;

      ScatterDataModifier::ScatterDataModifier(Q3DScatter *scatter)
          : m_graph(scatter),
            m_fieldLines(12),
            m_arrowsPerLine(16),
            m_magneticField(new QScatter3DSeries),
            m_sun(new QCustom3DItem),
            m_magneticFieldArray(0),
            m_angleOffset(0.0f),
            m_angleStep(doublePi / m_arrowsPerLine / animationFrames)
      {
          m_graph->setShadowQuality(QAbstract3DGraph::ShadowQualityNone);
          m_graph->scene()->activeCamera()->setCameraPreset(Q3DCamera::CameraPresetFront);

          // Magnetic field lines use custom narrow arrow
          m_magneticField->setItemSize(0.2f);
          m_magneticField->setMesh(QAbstract3DSeries::MeshUserDefined);
          m_magneticField->setUserDefinedMesh(QStringLiteral(":/mesh/narrowarrow.obj"));
          QLinearGradient fieldGradient(0, 0, 16, 1024);
          fieldGradient.setColorAt(0.0, Qt::black);
          fieldGradient.setColorAt(1.0, Qt::white);
          m_magneticField->setBaseGradient(fieldGradient);
          m_magneticField->setColorStyle(Q3DTheme::ColorStyleRangeGradient);

          // For 'sun' we use a custom large sphere
          m_sun->setScaling(QVector3D(0.07f, 0.07f, 0.07f));
          m_sun->setMeshFile(QStringLiteral(":/mesh/largesphere.obj"));
          QImage sunColor = QImage(2, 2, QImage::Format_RGB32);
          sunColor.fill(QColor(0xff, 0xbb, 0x00));
          m_sun->setTextureImage(sunColor);

          m_graph->addSeries(m_magneticField);
          m_graph->addCustomItem(m_sun);

          // Configure the axes according to the data
          m_graph->axisX()->setRange(-horizontalRange, horizontalRange);
          m_graph->axisY()->setRange(-verticalRange, verticalRange);
          m_graph->axisZ()->setRange(-horizontalRange, horizontalRange);
          m_graph->axisX()->setSegmentCount(int(horizontalRange));
          m_graph->axisZ()->setSegmentCount(int(horizontalRange));

          QObject::connect(&m_rotationTimer, &QTimer::timeout, this,
                           &ScatterDataModifier::triggerRotation);

          toggleRotation();
          generateData();
      }

      ScatterDataModifier::~ScatterDataModifier()
      {
          delete m_graph;
      }

      void ScatterDataModifier::generateData()
      {
          // Reusing existing array is computationally cheaper than always generating new array, even if
          // all data items change in the array, if the array size doesn't change.
          if (!m_magneticFieldArray)
              m_magneticFieldArray = new QScatterDataArray;

          int arraySize = m_fieldLines * m_arrowsPerLine;
          if (arraySize != m_magneticFieldArray->size())
              m_magneticFieldArray->resize(arraySize);

          QScatterDataItem *ptrToDataArray = &m_magneticFieldArray->first();

          for (float i = 0; i < m_fieldLines; i++) {
              float horizontalAngle = (doublePi * i) / m_fieldLines;
              float xCenter = ellipse_a * qCos(horizontalAngle);
              float zCenter = ellipse_a * qSin(horizontalAngle);

              // Rotate - arrow always tangential to origin
              QQuaternion yRotation = QQuaternion::fromAxisAndAngle(0.0f, 1.0f, 0.0f, horizontalAngle * radiansToDegrees);

              for (float j = 0; j < m_arrowsPerLine; j++) {
                  // Calculate point on ellipse centered on origin and parallel to x-axis
                  float verticalAngle = ((doublePi * j) / m_arrowsPerLine) + m_angleOffset;
                  float xUnrotated = ellipse_a * qCos(verticalAngle);
                  float y = ellipse_b * qSin(verticalAngle);

                  // Rotate the ellipse around y-axis
                  float xRotated = xUnrotated * qCos(horizontalAngle);
                  float zRotated = xUnrotated * qSin(horizontalAngle);

                  // Add offset
                  float x = xCenter + xRotated;
                  float z = zCenter + zRotated;

                  QQuaternion zRotation = QQuaternion::fromAxisAndAngle(0.0f, 0.0f, 1.0f, verticalAngle * radiansToDegrees);
                  QQuaternion totalRotation = yRotation * zRotation;

                  ptrToDataArray->setPosition(QVector3D(x, y, z));
                  ptrToDataArray->setRotation(totalRotation);
                  ptrToDataArray++;
              }
          }

          if (m_graph->selectedSeries() == m_magneticField)
              m_graph->clearSelection();

          m_magneticField->dataProxy()->resetArray(m_magneticFieldArray);
      }

      void ScatterDataModifier::setFieldLines(int lines)
      {
          m_fieldLines = lines;
          generateData();
      }

      void ScatterDataModifier::setArrowsPerLine(int arrows)
      {
          m_angleOffset = 0.0f;
          m_angleStep = doublePi / m_arrowsPerLine / animationFrames;
          m_arrowsPerLine = arrows;
          generateData();
      }

      void ScatterDataModifier::triggerRotation()
      {
          m_angleOffset += m_angleStep;
          generateData();
      }

      void ScatterDataModifier::toggleSun()
      {
          m_sun->setVisible(!m_sun->isVisible());
      }

      void ScatterDataModifier::toggleRotation()
      {
          if (m_rotationTimer.isActive())
              m_rotationTimer.stop();
          else
              m_rotationTimer.start(15);
      }