Fixed object rotations in the boxes demo.

When Math3D was introduced, the boxes demo was changed to use the
classes in the new module, but the change caused some bugs with the
object rotations. This commit should fix them.

Reviewed-by: Samuel

1 files changed, 7 insertions, 7 deletions

diff --git a/demos/boxes/trackball.cpp b/demos/boxes/trackball.cpp
index 9898441..60de6af 100644
--- a/demos/boxes/trackball.cpp
+++ b/demos/boxes/trackball.cpp
@@ -92,9 +92,9 @@ void TrackBall::move(const QPointF& p, const QQuaternion &transformation)
         {
             QLineF delta(m_lastPos, p);
             m_angularVelocity = 180*delta.length() / (PI*msecs);
-            m_axis = QVector3D(delta.dy(), -delta.dx(), 0.0f).normalized();
+            m_axis = QVector3D(-delta.dy(), delta.dx(), 0.0f).normalized();
             m_axis = transformation.rotateVector(m_axis);
-            m_rotation *= QQuaternion::fromAxisAndAngle(m_axis, delta.length());
+            m_rotation = QQuaternion::fromAxisAndAngle(m_axis, 180 / PI * delta.length()) * m_rotation;
         }
         break;
     case Sphere:
@@ -113,13 +113,13 @@ void TrackBall::move(const QPointF& p, const QQuaternion &transformation)
             else
                 currentPos3D.normalize();
 
-            m_axis = QVector3D::crossProduct(currentPos3D, lastPos3D);
-            float angle = asin(sqrt(QVector3D::dotProduct(m_axis, m_axis)));
+            m_axis = QVector3D::crossProduct(lastPos3D, currentPos3D);
+            float angle = 180 / PI * asin(sqrt(QVector3D::dotProduct(m_axis, m_axis)));
 
-            m_angularVelocity = 180*angle / (PI*msecs);
+            m_angularVelocity = angle / msecs;
             m_axis.normalize();
             m_axis = transformation.rotateVector(m_axis);
-            m_rotation *= QQuaternion::fromAxisAndAngle(m_axis, angle);
+            m_rotation = QQuaternion::fromAxisAndAngle(m_axis, angle) * m_rotation;
         }
         break;
     }
@@ -155,6 +155,6 @@ QQuaternion TrackBall::rotation() const
 
     QTime currentTime = QTime::currentTime();
     float angle = m_angularVelocity * m_lastTime.msecsTo(currentTime);
-    return m_rotation * QQuaternion::fromAxisAndAngle(m_axis, angle);
+    return QQuaternion::fromAxisAndAngle(m_axis, angle) * m_rotation;
 }