Выдержка из оригинальной справки. (NDL Gamebryo 1.1)
NiSpotLight is an object that represents a spotlight in a scene. Spotlights have a specific location and direction in space, as well as a distance attenuation function and an angle attenuation function. Location and distance attenuation are inherited from the NiPointLight class. The light direction is handled in the same way as it is in NiDirectionalLight--it shines down the model-space positive X-axis of the light.
Angular Attenuation Equation
Unless the angular attenuation exponent is something other than 1.0, Gamebryo uses linear attenuation from the spot direction to the edge of the light cone. If the angular attenuation exponent is not 1.0, its effects are renderer-dependent.
Spotlights are a subclass of point lights and illuminate objects with light rays that emanate from the light's location, but only in directions that fall within a desired angle from a specified direction (forming a cone of light). The light location (model-space origin), direction (model-space X vector) and angle (in degrees) are all used to define a spotlight. The spot light exponent is not currently supported: All spotlights have a linear attenuation from the spot direction to the edge of the cone. This light type is represented by the NiSpotLight in Gamebryo.
