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Context: Knowledge about hot, massive stars is usually inferred fromquantitative spectroscopy. To analyse non-spherical phenomena, the existing 1Dcodes must be extended to higher dimensions, and corresponding tools need to bedeveloped. Aims: We present a 3D radiative transfer code that is capable ofcalculating continuum and line scattering problems in the winds of hot stars.By considering spherically symmetric test models, we discuss potential errorsources, and indicate advantages and disadvantages by comparing differentsolution methods. Further, we analyse the UV resonance line formation in thewinds of rapidly rotating O stars. Methods: We consider both a (simplified)continuum model including scattering and thermal sources, and a UV resonanceline transition approximated by a two-level-atom. We applied theshort-characteristics (SC) method, using linear or monotonic B\'ezierinterpolations, to solve the equation of radiative transfer on a non-uniformCartesian grid. To calculate scattering dominated problems, our solution methodis supplemented by an accelerated $\Lambda$-iteration scheme. Results: For thespherical test models, the mean relative error of the source function is on the$5-20\,\%$ level, depending on the applied interpolation technique and thecomplexity of the considered model. All calculated line profiles are inexcellent agreement with corresponding 1D solutions. The predicted lineprofiles from fast rotating stars show a distinct behaviour as a function ofrotational speed and inclination. This behaviour is tightly coupled to the windstructure and the description of gravity darkening and stellar surfacedistortion. Conclusions: Our SC methods are ready to be used for quantitativeanalyses of UV resonance line profiles. When calculating optically thickcontinua, both SC methods give reliable results, in contrast to the alternativefinite-volume method.

A 3D short-characteristics method for continuum and line scattering problems in the winds of hot stars