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 <aeikum@codeweavers.com> Signed-off-by: Alexandre Julliard <julliard@winehq.org>

dsound: Fix rolloff factor calculation.
1671a83f · Andrew Eikum · Alexandre Julliard · c0b30432 · 1671a83f
Commit 1671a83f authored Dec 28, 2016 by Andrew Eikum Committed by Alexandre Julliard Dec 29, 2016
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sound3d.c dlls/dsound/sound3d.c +3 -1

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--- 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 */