1. A method of controlling example-based directional texture painting by a computing device, the method comprising: receiving, by the computing device, a source direction field of a source texture to be applied to a set of pixels to be synthesized; receiving, by the computing device, at least one input painting a target direction field in a user interface to be applied to the set of pixels; synthesizing, by the computing device, the set of pixels using the source texture and the source direction field such that the target direction field of the synthesized set of pixels corresponds to the source direction field; receiving, by the computing device, at least one subsequent input painting an update to the target direction field; and updating, by the computing device, the synthesized set of pixels using the updated target direction field.