Cube House

Files:

• sensors/cubehouse/camera.cpp
• sensors/cubehouse/camera.h
• sensors/cubehouse/cube.h
• sensors/cubehouse/light.cpp
• sensors/cubehouse/light.h
• sensors/cubehouse/lightmodel.cpp
• sensors/cubehouse/lightmodel.h
• sensors/cubehouse/material.cpp
• sensors/cubehouse/material.h
• sensors/cubehouse/painter.cpp
• sensors/cubehouse/painter.h
• sensors/cubehouse/painter_fixed.cpp
• sensors/cubehouse/painter_shader.cpp
• sensors/cubehouse/teapot.h
• sensors/cubehouse/view.cpp
• sensors/cubehouse/view.h
• sensors/cubehouse/main.cpp
• sensors/cubehouse/cubehouse.pro
• sensors/cubehouse/cubehouse.qrc

The Cube House example demonstrates the use of the accelerometer to drive a camera to create a pseudo-3D effect. It also demonstrates the use of a filter to smooth out the accelerometer values.

The accelerometer is created and the filter is added.

     sensor = new QAccelerometer(this);
     connect(sensor, SIGNAL(readingChanged()), this, SLOT(accelerometerTimeout()));
     sensor->addFilter(new smoothedaccelerometerfilter(this));
     sensor->start();

When new values are available, the view is recalculated.

 void View::accelerometerTimeout()
 {
     QVector3D g = gravity();
     mainCamera->setMotionAdjustment(g);
     roomCamera->setMotionAdjustment(g);
     update();
 }

 #define ACCEL_TO_G(v) (v / 9.80665)

 QVector3D View::gravity() const
 {
     qreal x = ACCEL_TO_G(sensor->reading()->x()) * sensitivity;
     qreal y = ACCEL_TO_G(sensor->reading()->y()) * sensitivity;
     qreal z = ACCEL_TO_G(sensor->reading()->z());

     return QVector3D(x, y, z);
 }

The filter is defined like this.

 class smoothedaccelerometerfilter : public QObject, public QAccelerometerFilter
 {
     qreal prevX;
     qreal prevY;
     qreal prevZ;
     bool havePrev;

 public:
     smoothedaccelerometerfilter(QObject *parent = 0)
         : QObject(parent)
         , QAccelerometerFilter()
         , prevX(0)
         , prevY(0)
         , prevZ(0)
         , havePrev(false)
     {
     }

     bool filter(QAccelerometerReading *reading)
     {
         // Smooth out the reported values.  Large changes are applied as-is,
         // and small jitters smooth to the rest position.
         if (havePrev) {
             qreal xdiff = reading->x() - prevX;
             qreal ydiff = reading->y() - prevY;
             qreal zdiff = reading->z() - prevZ;
 #define threshold 0.196133f
             if (qAbs(xdiff) < threshold && qAbs(ydiff) < threshold && qAbs(zdiff) < threshold) {
                 reading->setX(prevX + xdiff * 0.1f);
                 reading->setY(prevY + ydiff * 0.1f);
                 reading->setZ(prevZ + zdiff * 0.1f);
             }
         }
         prevX = reading->x();
         prevY = reading->y();
         prevZ = reading->z();
         havePrev = true;
         return true;
     }
 };