### Lighting

By default the colors assigned to pm3d objects are not dependent on orientation or viewing angle. This state corresponds to set pm3d nolighting. The command set pm3d lighting selects a simple lighting model consisting of a single fixed source of illumination contributing 50% of the overall lighting. The strength of this light relative to the ambient illumination can be adjusted by set pm3d lighting primary 4#4fraction5#5. Inclusion of specular highlighting can be adjusted by setting a fractional contribution:

        set pm3d lighting primary 0.50 specular 0.0   # no highlights
        set pm3d lighting primary 0.50 specular 0.6   # strong highlights