[Openal] EFX Clarifications

[Daniel PEACOCK]

Hi,

> > Well the problem is that the direct gain can be completely
> different when switching from one distance model to another.   In
> the simple case, of no distance model (AL_NONE) you would expect no
> air absorption either.
>
> So for no distance model, no air absorption is used.  That makes sense.
>
> What about for the linear and exponent models?
>
> I would have assumed they'd still use (distance -
> reference_distance), maybe clamped if the model requires it (this
> would include the inverse model too).

We do something a little bit different - but I don't think it will make
much difference if you use the same formula for each non-None distance
model.  Just make sure that for the non-clamped models (where distance can
be less than Reference Distance) that the Air Absorption calculation
doesn't actually amplify the signal ;)

Dan