Computes the lighting due to a single light and returns the shading as well as a value that is either 1 or 0 depending on whether the currently shaded spot is lit or not.

The function input allows you to change how the shading is computed, there is also an option to compute the illuminance, which is just the amount of light hitting a spot regardless of the surface normal.

• Colour Lambert shading for the selected light. This is the raw shading, not modified by any surface values. In that respect it is equivalent to a white surface with a diffuse value of 100%
• isLit 0 if the current spot is not lit by the light, 1 if it is.
• Radiosity The lighting due to radiosity. This output does not require a light to be selected.
• Caustics The lighting due to caustics. This output does not require a light to be selected.