  We present a simple model for galaxy attenuation by distilling SKIRT
radiative transfer calculations for ~100,000 EAGLE galaxies at redshifts z=2-0.
Our model adapts the two component screen model of Charlot & Fall (2000),
parametrising the optical depth and slope of the ISM screen using the average
dust surface density, $\Sigma_{\rm dust}$. We recover relatively tight
relations between these parameters for the EAGLE sample, but also provide the
scatter in these parameter owing to the morphological variation and orientation
of galaxies. We also find that these relations are nearly independent of
redshift in the EAGLE model. By pairing our model with an empirical
prescription for birth clouds below the resolution scale of the simulation, we
reproduce the observed relation between attenuation slope and optical depth for
the first time in a cosmological simulation. We demonstrate that this result is
remarkably independent of the attenuation properties assumed for birth cloud
screen, merely requiring a boosted attenuation for infant stars. We present
this model with a view to interpreting observations, as well as processing
semi-analytic models and other hydrodynamic simulations.
