Methods and apparatus for procedural directional texture generation. A procedural directional texture generation method may, for example, be used to design hair or hairstyles. The method may obtain one or more strokes, one or more optional masks, and one or more optional user maps. One or more interpolated orientation maps may be generated from the input. The orientation maps, possibly along with one or more optional user maps, may be used to compute synthetic low-frequency lighting. A noise map may be generated at one or more frequencies and used, along with the interpolated maps, to generate high-frequency lighting. Alternatively, a flow-guided texture synthesis method may be used to generate high-frequency lighting. The low- and high-frequency lighting may then be combined to generate a desired frequency spectrum. Color may be added to the full structure, or alternatively color may be added at an earlier step.