Fbx and Light Attenuation

It’s been a long time since I posted, and I have alot of new code to update. One of the most useful that I figured out a couple of days ago was how Maya and FBX store attenuation for lighting.

A lot of examples out there use the DecayStart as the attenuation value, but I’ve found that the value given doesn’t give a one for one mapping my code when compared with Maya, and in the case of quadratic attenuation, black.

In Maya you only have a dropdown box that allows you to select the attenuation type (constant, linear or quadratic), but no way to choose the value. So how can you know what those values are? They are always 1.o is what I found out, the scaling of the attenuation is controlled by the intensity property which gets multiplied by the colour.

 

From what I can tell, DecayStart is exactly what it says on the tin, its the start point for when the attenuation should begin to decay. Like DirectX’s range for light components.