  A numerical code for solving various Lyman alpha (Lya) radiative transfer
(RT) problems is presented. The code is suitable for an arbitrary,
three-dimensional distribution of Lya emissivity, gas temperature, density, and
velocity field. Capable of handling Lya RT in an adaptively refined grid-based
structure, it enables detailed investigation of the effects of clumpiness of
the interstellar (or intergalactic) medium. The code is tested against various
geometrically and physically idealized configurations for which analytical
solutions exist, and subsequently applied to three "Lyman-break galaxies",
extracted from high-resolution cosmological simulations at redshift z = 3.6.
Proper treatment of the Lya scattering reveals a diversity of surface
brightness (SB) and line profiles. Specifically, for a given galaxy the maximum
observed SB can vary by an order of magnitude, and the total flux by a factor
of 3 - 6, depending on the viewing angle. This may provide an explanation for
differences in observed properties of high-redshift galaxies, and in particular
a possible physical link between Lyman-break galaxies and regular Lya emitters.
