dsound: Fix angle to sound source calculation.

[Andrew Eikum]

Forwarding on to wine-devel, Stas, and Ruslan from Bug 38041.

Any thoughts on the coning breakage, Stas?

Andrew

On Mon, Mar 23, 2015 at 09:52:32PM +0000, Mark Harmstone wrote:
> Hi,
> 
> I've had a play with it, and yes, I think he's right. It seems to be a
> lot more robust than my code. One thing though that I think he's
> overlooked is that he changes the behaviour of AngleBetweenVectorsRad,
> which is called by AngleBetweenVectorsDeg and thus the coning code -
> I think this patch will probably break that.
> 
> I've not tested it yet, but there's a chance this patch might fix
> bug 38041.
> 
> Mark
> 
> On 23/03/15 14:39, Andrew Eikum wrote:
> > This seems sane to me, but I never had a good grasp on this to begin
> > with. Does it look OK to you, Mark?
> > 
> > Andrew
> > 
> > On Sun, Mar 22, 2015 at 08:59:15PM +0300, Стас Цымбалов wrote:
> >> This patch fixes incorrect sound positioning in dsound.
> >> As of now, angle to sound source is calculated as angle between
> >> vDistance and vOrientFront.
> >> This leads to incorrect results for all sources that are not in the
> >> same plane as speakers.
> >> In extreme case: for sources directly above or below origin, angle is
> >> calculated to -90 degrees, and they are played in the left speaker.
> >>
> >> This patch changes angle calculation: angle to sound source is
> >> calculated as angle between vDistance and plane given by vectors
> >> vOrientFront and vOrientTop.
> >> ---
> >>  dlls/dsound/sound3d.c | 25 ++++++++++++++-----------
> >>  1 file changed, 14 insertions(+), 11 deletions(-)
> > 
> >> From 1ebe3761b0d6acfca58cec17472336a05b7f2679 Mon Sep 17 00:00:00 2001
> >> From: Stas Cymbalov <dummyunit at gmail.com>
> >> Date: Sun, 22 Mar 2015 18:22:49 +0300
> >> Subject: dsound: Fix angle to sound source calculation.
> >>
> >> ---
> >>  dlls/dsound/sound3d.c | 25 ++++++++++++++-----------
> >>  1 file changed, 14 insertions(+), 11 deletions(-)
> >>
> >> diff --git a/dlls/dsound/sound3d.c b/dlls/dsound/sound3d.c
> >> index 9a0226a..ffd4d45 100644
> >> --- a/dlls/dsound/sound3d.c
> >> +++ b/dlls/dsound/sound3d.c
> >> @@ -112,7 +112,6 @@ static inline D3DVALUE AngleBetweenVectorsRad (const D3DVECTOR *a, const D3DVECT
> >>  
> >>  	cos = product/(la*lb);
> >>  	angle = acos(cos);
> >> -	if (cos < 0.0f) { angle -= M_PI; }
> >>  	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;	
> >> @@ -264,16 +263,20 @@ void DSOUND_Calc3DBuffer(IDirectSoundBufferImpl *dsb)
> >>  	else
> >>  	{
> >>  		vLeft = VectorProduct(&dsb->device->ds3dl.vOrientFront, &dsb->device->ds3dl.vOrientTop);
> >> -		flAngle = AngleBetweenVectorsRad(&dsb->device->ds3dl.vOrientFront, &vDistance);
> >> -		flAngle2 = AngleBetweenVectorsRad(&vLeft, &vDistance);
> >> -
> >> -		/* AngleBetweenVectorsRad performs a dot product, which gives us the cosine of the angle
> >> -		 * between two vectors. Unfortunately, because cos(theta) = cos(-theta), we've no idea from
> >> -		 * this whether the sound is to our left or to our right. We have to perform another dot
> >> -		 * product, with a vector at right angles to the initial one, to get the correct angle.
> >> -		 * The angle should be between -180 degrees and 180 degrees. */
> >> -		if (flAngle < 0.0f) { flAngle += M_PI; }
> >> -		if (flAngle2 > 0.0f) { flAngle = -flAngle; }
> >> +		/* To calculate angle to sound source we need to:
> >> +		 * 1) Get angle between vDistance and a plane on which angle to sound source should be 0.
> >> +		 *    Such a plane is given by vectors vOrientFront and vOrientTop, and angle between vector
> >> +		 *    and a plane equals to M_PI_2 - angle between vector and normal to this plane (vLeft in this case).
> >> +		 * 2) Determine if the source is behind or in front of us by calculating angle between vDistance
> >> +		 *    and vOrientFront.
> >> +		 */
> >> +		flAngle = AngleBetweenVectorsRad(&vLeft, &vDistance);
> >> +		flAngle2 = AngleBetweenVectorsRad(&dsb->device->ds3dl.vOrientFront, &vDistance);
> >> +		if (flAngle2 > M_PI_2)
> >> +			flAngle = -flAngle;
> >> +		flAngle -= M_PI_2;
> >> +		if (flAngle < -M_PI)
> >> +			flAngle += 2*M_PI;
> >>  	}
> >>  	TRACE("panning: Angle = %f rad, lPan = %d\n", flAngle, dsb->volpan.lPan);
> >>  
> >> -- 
> >> 2.0.5
> >>
> > 
> >>
> > 
>