A sketch-based interface within an animation engine provides an end-user with tools for creating emitter textures and oscillator textures. The end-user may create an emitter texture by sketching one or more patch elements and then sketching an emitter. The animation engine animates the sketch by generating a stream of patch elements that emanate from the emitter. The end-user may create an oscillator texture by sketching a patch that includes one or more patch elements, and then sketching a brush skeleton and an oscillation skeleton. The animation engine replicates the patch along the brush skeleton, and then interpolates the replicated patches between the brush skeleton and the oscillation skeleton, thereby causing those replicated patches to periodically oscillate between the two skeletons.