@Override
    public void tick(float delta) {
        if (mouseTracker.isDragging()) {
            //float dtheta = (float) dx/width;
            float dtheta = 0;
            float dz = 0;
            float unitStep = (float) Math.PI * delta / 8;//4 seconds to 90 - sloow!

            if (mouseTracker.getDeltaX() > 20)
                dtheta = -unitStep;

            if (mouseTracker.getDeltaX() < -20)
                dtheta = unitStep;

            if (mouseTracker.getDeltaY() > 20)
                dz = delta / 4;

            if (mouseTracker.getDeltaY() < -20)
                dz = -delta / 4;

            app.cameraMan.rotateEyeAboutFocus(-dtheta);
            app.cameraMan.translateZ(-dz);
        }

        repaint();
    }