  Cen X-3 is a compact high mass X-ray binary likely powered by Roche lobe
overflow. We present a phase-resolved X-ray spectral and timing analysis of two
pointed XMM-Newton observations. The first one took place during a normal state
of the source, when it has a luminosity $L_{\rm X}\sim 10^{36}$ erg s$^{-1}$.
This observation covered orbital phases $\phi= 0.00-0.37$, i.e. the egress from
the eclipse. The egress lightcurve is highly structured, showing distinctive
intervals. We argue that different intervals correspond to the emergence of
different emitting structures. The lightcurve analysis enables us to estimate
the size of such structures around the compact star, the most conspicuous of
which has a size $\sim 0.3R_{*}$, of the order of the Roche lobe radius. During
the egress, the equivalent width of Fe emission lines, from highly ionized
species, decreases as the X-ray continuum grows. On the other hand, the
equivalent width of the Fe K$\alpha$ line, from near neutral Fe, strengthens.
This line is likely formed due to the X-ray illumination of the accretion
stream. The second observation was taken when the source was 10 times X-ray
brighter and covered the orbital phases $\phi= 0.36-0.80$. The X-ray lightcurve
in the high state shows dips. These dips are not caused by absorption but can
be due to instabilities in the accretion stream. The typical dip duration, of
about 1000~s, is much longer than the timescale attributed to the accretion of
the clumpy stellar wind of the massive donor star, but is similar to the
viscous timescale at the inner radius of the accretion disk.
