how does Light.Attenuation work?

Attenuation of a light is a mathematical function that determines how much light is transmitted to a given distance from its source.

Simply put, it describes how the light contribution next to the light is very bright, and how its very dim (or none at all) a long way from the light.

The D3D fixed-function lighting equations calculate based on the following formula:

       1 ------------(aD^2 + bD + c)

where
a = Attenuation0
b = Attenuation1
c = Attenuation2
D = Distance from the light source (D^2 is D*D)

you use it to create a quadtratic equation basically. Using clever values you can have a light that fades out very quickly towards the edge of its range, or one that fades extremely quickly but maintains a small contribution for a large distance.

hth
Jack

Microsoft should copy & paste your answer into the directX-SDK.

Thanks.

Quote:

Original post by otomo Microsoft should copy & paste your answer into the directX-SDK.

It's already there, in the "Attenuation and spotlight factor" page (type it in the index) [smile]

Quote:

Original post by Coder It's already there, in the "Attenuation and spotlight factor" page (type it in the index) [smile]

uups, not in my version. did i mention that i work with the sdk for managed DirectX?

Quote:

Original post by otomo Quote: Original post by Coder It's already there, in the "Attenuation and spotlight factor" page (type it in the index) [smile] uups, not in my version. did i mention that i work with the sdk for managed DirectX?

It seems that the C++ Documentation has much more information than the Managed Documentation, which for the most part only contains coding related articles.
You should make use of the C++ Documentation, eventhough coding with Managed.

Quote:

Original post by Pipo DeClown It seems that the C++ Documentation has much more information than the Managed Documentation, which for the most part only contains coding related articles. You should make use of the C++ Documentation, eventhough coding with Managed.

thanks for the advice. I began to suspect that, too. I just started downloading, and hope to get more and better information of how DirectX works, now. Thanks.