Phase Functions

In the framework, phase functions are embedded in so-called scattering functions. Scattering functions are based on a density function and a phase function, whereas the phase function defines the amount of light that is in-scattered into the viewing direction at a point $X$ and the density function defines the albedo at this point $X$. Different phase functions can be used: isotropic scattering, Lambert scattering, Henyey-Greenstein scattering, Mie scattering, .... The simple interface to phase functions is $getColor(X)$. Because in our framework phase functions act the same way as transfer functions (returning a color) they also can be combined the same way, using $GeneralTransfer$ and $MappedTransfer$ functions.