shadow_bound Subroutine

    subroutine shadow_bound(self, center, radius)
        class(ShadowCones), intent(in) :: self
        real(wp), intent(out) :: center(3), radius          !! the bounding sphere, frame coordinates (scene units)
        real(wp) :: lo, hi, r
        integer :: k
        center = 0.0_wp
        radius = 0.0_wp
        lo = huge(1.0_wp)
        hi = -huge(1.0_wp)
        r = 0.0_wp
        do k = 1, n_regions
            if (.not. self%region(k)%drawn) cycle
            lo = min(lo, self%region(k)%z0)
            hi = max(hi, self%region(k)%z1)
            r = max(r, self%region(k)%r0, self%region(k)%r1)
        end do
        if (hi < lo) return
        center(3) = 0.5_wp * (lo + hi)
        radius = hypot(0.5_wp * (hi - lo), r)
    end subroutine shadow_bound