trackball.cpp Example File
demos/boxes/trackball.cpp
#include "trackball.h"
TrackBall::TrackBall(TrackMode mode)
: m_angularVelocity(0)
, m_paused(false)
, m_pressed(false)
, m_mode(mode)
{
m_axis = gfx::Vector3f::vector(0, 1, 0);
m_rotation = gfx::Quaternionf::quaternion(1.0f, 0.0f, 0.0f, 0.0f);
m_lastTime = QTime::currentTime();
}
TrackBall::TrackBall(float angularVelocity, const gfx::Vector3f& axis, TrackMode mode)
: m_axis(axis)
, m_angularVelocity(angularVelocity)
, m_paused(false)
, m_pressed(false)
, m_mode(mode)
{
m_rotation = gfx::Quaternionf::quaternion(1.0f, 0.0f, 0.0f, 0.0f);
m_lastTime = QTime::currentTime();
}
void TrackBall::push(const QPointF& p, const gfx::Quaternionf &)
{
m_rotation = rotation();
m_pressed = true;
m_lastTime = QTime::currentTime();
m_lastPos = p;
m_angularVelocity = 0.0f;
}
void TrackBall::move(const QPointF& p, const gfx::Quaternionf &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 = delta.length() / msecs;
m_axis = gfx::Vector3f::vector(delta.dy(), -delta.dx(), 0.0f).normalized();
m_axis = transformation.transform(m_axis);
m_rotation *= gfx::Quaternionf::rotation(delta.length(), m_axis);
}
break;
case Sphere:
{
gfx::Vector3f lastPos3D = gfx::Vector3f::vector(m_lastPos.x(), m_lastPos.y(), 0);
float sqrZ = 1 - lastPos3D.sqrNorm();
if (sqrZ > 0)
lastPos3D[2] = sqrt(sqrZ);
else
lastPos3D.normalize();
gfx::Vector3f currentPos3D = gfx::Vector3f::vector(p.x(), p.y(), 0);
sqrZ = 1 - currentPos3D.sqrNorm();
if (sqrZ > 0)
currentPos3D[2] = sqrt(sqrZ);
else
currentPos3D.normalize();
m_axis = gfx::Vector3f::cross(currentPos3D, lastPos3D);
float angle = asin(sqrt(m_axis.sqrNorm()));
m_angularVelocity = angle / msecs;
m_axis.normalize();
m_axis = transformation.transform(m_axis);
m_rotation *= gfx::Quaternionf::rotation(angle, m_axis);
}
break;
}
m_lastPos = p;
m_lastTime = currentTime;
}
void TrackBall::release(const QPointF& p, const gfx::Quaternionf &transformation)
{
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;
}
gfx::Quaternionf TrackBall::rotation() const
{
if (m_paused || m_pressed)
return m_rotation;
QTime currentTime = QTime::currentTime();
float angle = m_angularVelocity * m_lastTime.msecsTo(currentTime);
return m_rotation * gfx::Quaternionf::rotation(angle, m_axis);
}