trackball.cpp Example File

graphicsview/boxes/trackball.cpp
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#include "trackball.h" #include "scene.h" #include <cmath> //============================================================================// // TrackBall // //============================================================================// TrackBall::TrackBall(TrackMode mode) : m_angularVelocity(0) , m_paused(false) , m_pressed(false) , m_mode(mode) { m_axis = QVector3D(0, 1, 0); m_rotation = QQuaternion(); m_lastTime = QTime::currentTime(); } TrackBall::TrackBall(float angularVelocity, const QVector3D& axis, TrackMode mode) : m_axis(axis) , m_angularVelocity(angularVelocity) , m_paused(false) , m_pressed(false) , m_mode(mode) { m_rotation = QQuaternion(); m_lastTime = QTime::currentTime(); } void TrackBall::push(const QPointF& p, const QQuaternion &) { m_rotation = rotation(); m_pressed = true; m_lastTime = QTime::currentTime(); m_lastPos = p; m_angularVelocity = 0.0f; } void TrackBall::move(const QPointF& p, const QQuaternion &transformation) { if (!m_pressed) return; QTime currentTime = QTime::currentTime(); int msecs = m_lastTime.msecsTo(currentTime); if (msecs <= 20) return; switch (m_mode) { case Plane: { QLineF delta(m_lastPos, p); m_angularVelocity = 180*delta.length() / (PI*msecs); m_axis = QVector3D(-delta.dy(), delta.dx(), 0.0f).normalized(); m_axis = transformation.rotatedVector(m_axis); m_rotation = QQuaternion::fromAxisAndAngle(m_axis, 180 / PI * delta.length()) * m_rotation; } break; case Sphere: { QVector3D lastPos3D = QVector3D(m_lastPos.x(), m_lastPos.y(), 0.0f); float sqrZ = 1 - QVector3D::dotProduct(lastPos3D, lastPos3D); if (sqrZ > 0) lastPos3D.setZ(std::sqrt(sqrZ)); else lastPos3D.normalize(); QVector3D currentPos3D = QVector3D(p.x(), p.y(), 0.0f); sqrZ = 1 - QVector3D::dotProduct(currentPos3D, currentPos3D); if (sqrZ > 0) currentPos3D.setZ(std::sqrt(sqrZ)); else currentPos3D.normalize(); m_axis = QVector3D::crossProduct(lastPos3D, currentPos3D); float angle = 180 / PI * std::asin(std::sqrt(QVector3D::dotProduct(m_axis, m_axis))); m_angularVelocity = angle / msecs; m_axis.normalize(); m_axis = transformation.rotatedVector(m_axis); m_rotation = QQuaternion::fromAxisAndAngle(m_axis, angle) * m_rotation; } break; } m_lastPos = p; m_lastTime = currentTime; } void TrackBall::release(const QPointF& p, const QQuaternion &transformation) { // Calling move() caused the rotation to stop if the framerate was too low. move(p, transformation); m_pressed = false; } void TrackBall::start() { m_lastTime = QTime::currentTime(); m_paused = false; } void TrackBall::stop() { m_rotation = rotation(); m_paused = true; } QQuaternion TrackBall::rotation() const { if (m_paused || m_pressed) return m_rotation; QTime currentTime = QTime::currentTime(); float angle = m_angularVelocity * m_lastTime.msecsTo(currentTime); return QQuaternion::fromAxisAndAngle(m_axis, angle) * m_rotation; }