[DirectX 8.1 C/C++ Programmer's Reference] Attenuation and Spotlight Terms (100%)

DirectX 8.1 (C++) > DirectX Graphics > Programmers Guide > Using Direct3D > Lights and Materials > Mathematics of Lighting

[DirectX October 2006 Documentation] Attenuation and Spotlight Factor (76.9791666666667%)

DirectX Graphics > Direct3D 9 > Programming Guide > Getting Started > Lights and Materials > Mathematics of Lighting