This operator is only available in Surface VOP networks. It contains other VOP operators, and executes the code for the contained operators once for every light that affects the surface being shaded.

This operator should only be used by advanced users with a good understanding of shading and rendering. For most purposes, the Lighting Model operator will provide all the functionality necessary to generate convincing and realistic materials. Within the illuminance loop, the Global Variables operator will change slightly. Two additional outputs will be available: the Color of the current light (Cl) and the direction from the point on the surface being shaded to the light (L). As is always the case within an illuminance loop, the values of these global variables are reset for each iteration through the code.

Any value that you wish to modify inside the illuminance loop must be provided as an input. The outputs of the Illuminance Loop operator will contain the modified versions of the inputs once the loop exits. The actual values wired into the Illuminance Loop inputs are never modified, and so can be connected to other operators in the network; but remember that the values from these operators will always be the values unmodified by the Illuminance Loop operator.

LIGHT_AMBIENT  = 0x01
LIGHT_DIFFUSE  = 0x02
LIGHT_SPECULAR = 0x04