Andrew Eikum : dsound: Fix rolloff factor calculation.

[Alexandre Julliard]

Module: wine
Branch: master
Commit: 1671a83f55bee46ee57cc0c8869e943d67f14ea5
URL:    http://source.winehq.org/git/wine.git/?a=commit;h=1671a83f55bee46ee57cc0c886...

Author: Andrew Eikum 
Date:   Wed Dec 28 14:02:54 2016 -0600

dsound: Fix rolloff factor calculation.

We should treat the rolloff factor as a factor of the distance of the
buffer. For example, a rolloff factor of 2 should treat the buffer as if
it were twice as far away from the listener as it is.

The previous calculation would instead double the decibels of
attenuation.

Signed-off-by: Andrew Eikum 
Signed-off-by: Alexandre Julliard

---

dlls/dsound/sound3d.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/dlls/dsound/sound3d.c b/dlls/dsound/sound3d.c
index b416cdc..4f07125 100644
--- a/dlls/dsound/sound3d.c
+++ b/dlls/dsound/sound3d.c
@@ -205,9 +205,11 @@ void DSOUND_Calc3DBuffer(IDirectSoundBufferImpl *dsb)

if (flDistance < dsb->ds3db_ds3db.flMinDistance)
    	flDistance = dsb->ds3db_ds3db.flMinDistance;
+
+	flDistance = dsb->ds3db_ds3db.flMinDistance + (flDistance - dsb->ds3db_ds3db.flMinDistance) * dsb->device->ds3dl.flRolloffFactor;
    
    /* attenuation proportional to the distance squared, converted to millibels as in lVolume*/
-	lVolume -= log10(flDistance/dsb->ds3db_ds3db.flMinDistance * flDistance/dsb->ds3db_ds3db.flMinDistance)*1000 * dsb->device->ds3dl.flRolloffFactor;
+	lVolume -= log10(flDistance/dsb->ds3db_ds3db.flMinDistance * flDistance/dsb->ds3db_ds3db.flMinDistance)*1000;
    TRACE("dist. att: Distance = %f, MinDistance = %f => adjusting volume %d to %f\n", flDistance, dsb->ds3db_ds3db.flMinDistance, dsb->ds3db_lVolume, lVolume);

/* conning */