** Specular reflectance. **

** R = SPECULAR(Nx,Ny,Nz,S,V) returns the reflectance of a surface with **

** normal vector components [Nx,Ny,Nz]. S and V specify the direction **

** to the light source and to the viewer, respectively. They can be **

** three vectors [x,y,z] or two vectors [Az, El] with azimuth and **

** elevation. **

** **

** **

** The specular highlight is strongest when the normal vector is in the **

** direction of (S+V)/2 where S is the source direction, and V is the **

** view direction. **

** **

** **

** The surface spread exponent can be specified by including a sixth **

** argument as in specular(Nx,Ny,Nz,S,V,spread). **

** **

** **

** See also DIFFUSE , SURFNORM , SURFL . **

** **