On Mon, Jul 23, 2018 at 10:51:49PM +0300, Ruslan Kabatsayev wrote:
Just curious, which cases does this fix? The ones when fabs(cos)>1 due to rounding errors? Or is acos broken for arguments near but not exceeding ±1?
Pretty sure it's rounding errors that result in fabs(cos)>1. That causes acos to return NAN, and bad things happen to audio volumes. I'd be surprised if acos is broken like the 2nd case you mention. Andrew
On 23/07/2018, Andrew Eikum <aeikum(a)codeweavers.com> wrote:
Signed-off-by: Andrew Eikum <aeikum(a)codeweavers.com> ---
v2: Remove old calculation, thanks Nikolay.
dlls/dsound/sound3d.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-)
diff --git a/dlls/dsound/sound3d.c b/dlls/dsound/sound3d.c index 03fd3d4678..6ca79c1bbc 100644 --- a/dlls/dsound/sound3d.c +++ b/dlls/dsound/sound3d.c @@ -111,7 +111,13 @@ static inline D3DVALUE AngleBetweenVectorsRad (const D3DVECTOR *a, const D3DVECT return 0;
cos = product/(la*lb); - angle = acos(cos); + if(fabs(1 - cos) < 0.0001f){ + angle = 0; + }else if(fabs(-1 - cos) < 0.0001f){ + angle = M_PI; + }else{ + angle = acos(cos); + } TRACE("angle between (%f,%f,%f) and (%f,%f,%f) = %f radians (%f degrees)\n", a->x, a->y, a->z, b->x, b->y, b->z, angle, RadToDeg(angle)); return angle; -- 2.18.0