Add port audio/libnoise:
libnoise is a portable C++ library that is used to generate coherent
noise, a type of smoothly-changing noise. libnoise can generate
Perlin noise, ridged multifractal noise, and other types of
Coherent noise is often used by graphics programmers to generate
natural-looking textures, planetary terrain, and other things. The
mountain scene shown above was rendered in Terragen with a terrain
file generated by libnoise. You can also view some other examples of
what libnoise can do.
In libnoise, coherent-noise generators are encapsulated in classes
called noise modules. There are many different types of noise
modules. Some noise modules can combine or modify the outputs of
other noise modules in various ways; you can join these modules
together to generate very complex coherent noise.