From: Jason Main <jasonm AT hpbs1079 DOT fooultrabar DOT boi DOT hp DOT com>
Newsgroups: rec.games.programmer,comp.ai.games,comp.os.msdos.djgpp
Subject: Re: Smart stereo sound effects
Date: Mon, 22 Dec 1997 16:05:23 -0700
Organization: hp
Lines: 34
Message-ID: <349EF233.65C0@hpbs1079.fooultrabar.boi.hp.com>
References: <349AA5AA DOT 5372 AT oce DOT nl> <349DF2E5 DOT 2848 AT ns DOT sympatico DOT ca>
NNTP-Posting-Host: hpb14677.boi.hp.com
Mime-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Transfer-Encoding: 7bit
To: djgpp AT delorie DOT com
DJ-Gateway: from newsgroup comp.os.msdos.djgpp
Precedence: bulk

Klaas wrote:
> 
> > My problem is that a lot of events happen, some on the visible area of
> > the screen, some others not visible.
> > In case of an event how can I decide if I must play the according
> > soundeffect (depending on the position of the vehicle in relation to the
> > visible area)
> 
> My guess would be to see if the explosion is with the screen ie.
> if ObjX > ScreenLeft and ObjX < ScreenLeft + ScreenWidth and (Y
> tests...)
>         (play sound)
> 
> > How is the volume altered in relation to the distance and position of
> > the event.
> 
> well, most games just play the sound at a certain loudness if the event
> is on the screen, and very faintly otherwise (example: Z)  Though, I
> suppose teh volume could be scaled using pythagorean distance:
> 
> sqr((ObjX-CurX)^2 + (ObjY-CurY)^2) (where CurX/Y are player's position)
> then scale that value from your lowest desired volume to your highest,
> then
> to compute final volume, subtract it from highest desired volume.

It is much beter to use the inversed squared distance (IE vol = 1/
((y1-y2)^2 + (x1-x2)^2).   This is more acurate and faster as well
as it eliminates the sqrt.

> 
> > Is it possible to include surround soundeffects?
> Yes!   The one catch is that to do this over the midi channal you have to
have a wavetable card.   For the digital chanal its just a matter of mixing
a couple of pre filtered sources.