[Openal] Filter

[Luis]

Hi Andy.
Just checking, are you reassigning the filter to the source after modifying
its parameters? You must do this or the new parameters won't affect the
source at all.

Hope that helps

On 10/4/07, Andy Patrick <Andy.Patrick at rebellion-derby.com> wrote:
>
>  Hello all,
>
> We're looking at playing around with the per-voice filter in the Effects
> Extension, in preparation for occlusion etc. We'd also like to change the
> filter over distance using a method that offers more control than the
> in-built distance filter in OpenAL, which I seem to remember reading about
> but can't now find a reference to!
>
> I understand that the low pass filter cut-off (-3dB point) is fixed at
> 4KHz, and the slope is fixed at -6dB/octave. What I don't understand is how
> the available parameters - AL_LOWPASS_GAIN and AL_LOWPASS_GAINHF - relate to
> that. I assumed that GAIN would modify the gain to the left of the cut-off
> point, and GAINHF would modify the gain to the right of the cut-off point.
> However, my attempts at varying GAINHF from 0 to 1 by distance doesn't seem
> to change the sound very much, and based on this assumption setting both
> GAIN and GAINHF to 0 would silence the sound, which it doesn't.
>
> Could someone please explain what the intent of these settings is, and
> briefly suggest how I might be able to implement the effects I'm after? I'm
> using OpenAL 1.1 on the Windows platform, primarily.
>
> Many thanks
>
> Andy P
>
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>


-- 
Luis
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