In this paper, we define complex solids by real functions. Just from r
elatively small formulae we produce highly detailed complex objects an
d are able to manipulate and transform them producing more complex one
s. We show how complex static and time-dependent objects can be create
d with the use of so-called R-functions. Then, we consider just one lo
ng-standing problem, hair modelling, and show how our functionally bas
ed model can be applied there. In modelling hair, we represent it with
solid noise and subsequently unify it with the solid being made hairy
. The hair and the solid are defined by real functions and the resulta
nt hairy solid is in turn functionally defined and can be an argument
for other operations. We are able to control length, thickness and cur
liness of hair and to obtain different hairstyles varying defining fun
ctions and applying set-theoretic operations to solid hair.