Composite Map Blend Modes Math - not directly Vray related

[Robert1977]

Dear users,

I write a kind of generic fx-shader that mimics most of the VrayMaterial for use in interactive scenarios.
Currently I code the several blend modes for the 3dsmax standard composite map, and I got all of them except one:

Spotlight Blend.

In the documentation it says:

"Same as Spotlight but also adds ambient illumination to B".

So Spotlight itself is this:
"like multiply, bit with twice the brightness"
result = 2 * image1 * image2

So the code I tried for spotlight blend is this:
result = 2 * image1 * (image2 + 0.5)

But the result is a bit too bright. It seems not to be as simple. Does anybody have the code for spotlight blend? I trade some other blend modes if somebody wants to know .

Thanks and best regards
Robert

[vlado]

The source of the Composite map is included in the 3ds Max SDK in the samples\materials\composite.cpp file.

Best regards,
Vlado

[Robert1977]

Thanks, this has saved my life.

Cheers

Robert