/**
* @brief Compute the trackball's translation, using stored initial and final position vectors.
*/
void computeTranslationVector (void)
{
Eigen::Vector2f translationFactor = finalTranslationPosition - initialTranslationPosition;
translationVector += quaternion.inverse() * Eigen::Vector3f(translationFactor[0],translationFactor[1], 0.0);
}
