Cinder glNext: Mapping mousewheel/scroll to Cinder's CameraPersp zoom

mayacam_zoom

//      CameraPersp         mCameraPersp;
//      float               newEyeZ; //holds our current eye Z point
//
void mouseWheel(MouseEvent event)
{
    float mouseDelta = event.getWheelIncrement() *5.f;
    float newCOI = powf( 2.71828183f, -mouseDelta / 500.0f ) * mCameraPersp.getCenterOfInterest();
    vec3 oldTarget = mCameraPersp.getCenterOfInterestPoint();
    vec3 newEye = oldTarget - mCameraPersp.getViewDirection() * newCOI;
    newEyeZ = newEye.z;
    mCameraPersp.setEyePoint( newEye );
    mCameraPersp.setCenterOfInterest( newCOI );
}