pub(crate) fn make_integrator(
    integrator_name: &String,
    filter_width: Float,
    xres: i32,
    yres: i32,
    fov: Float,
    clipsta: Float,
    animated_cam_to_world: AnimatedTransform,
    pixelsamples: i32,
    integrator_params: ParamSet
) -> Option<Box<Integrator>>