The Area Parameters are located in an area light’s Control Window (see Use the control window).
Controls how quickly light intensity decreases with distance. The Decay setting has no effect at distances less than 1 unit.
The Decay parameter works differently for volume lights (see Decay). Valid settings are 0, 1, 2 or 3. The default setting is 1.
| 0 | no decay; light reaches everything |
| 1 | light intensity decreases directly (linearly) with distance (slower than real world light) |
| 2 | light intensity decreases proportionally with the square of distance (the same as real world light) |
| 3 | light intensity decreases proportionally with the cube of distance (faster than real world light) |
