Add a source radius property that determines the directionality of a sound

At 0 distance from the listener, the sound is omni-directional. As the source
and listener become 'radius' units apart, the sound becomes more directional.

With HRTF, an omni-directional sound is handled using 0-delay, pass-through
filter coefficients, which is blended with the real delay and coefficients as
needed to become more directional.

3 files changed, 70 insertions, 43 deletions

diff --git a/Alc/ALu.c b/Alc/ALu.c
index 42bb50fc..2048f5fc 100644
--- a/Alc/ALu.c
+++ b/Alc/ALu.c
@@ -425,7 +425,7 @@ ALvoid CalcNonAttnSourceParams(ALactivesource *src, const ALCcontext *ALContext)
                 /* Get the static HRIR coefficients and delays for this
                  * channel. */
                 GetLerpedHrtfCoeffs(Device->Hrtf,
-                                    0.0f, chans[c].angle, DryGain,
+                                    0.0f, chans[c].angle, 1.0f, DryGain,
                                     src->Direct.Mix.Hrtf.Params[c].Coeffs,
                                     src->Direct.Mix.Hrtf.Params[c].Delay);
             }
@@ -899,6 +899,8 @@ ALvoid CalcSourceParams(ALactivesource *src, const ALCcontext *ALContext)
     {
         /* Use a binaural HRTF algorithm for stereo headphone playback */
         ALfloat delta, ev = 0.0f, az = 0.0f;
+        ALfloat radius = ALSource->Radius;
+        ALfloat dirfact = 1.0f;
 
         if(Distance > FLT_EPSILON)
         {
@@ -914,6 +916,8 @@ ALvoid CalcSourceParams(ALactivesource *src, const ALCcontext *ALContext)
             ev = asinf(clampf(Position[1], -1.0f, 1.0f));
             az = atan2f(Position[0], -Position[2]*ZScale);
         }
+        if(radius > Distance)
+            dirfact *= Distance / radius;
 
         /* Check to see if the HRIR is already moving. */
         if(src->Direct.Moving)
@@ -926,12 +930,10 @@ ALvoid CalcSourceParams(ALactivesource *src, const ALCcontext *ALContext)
             if(delta > 0.001f)
             {
                 ALuint counter = GetMovingHrtfCoeffs(Device->Hrtf,
-                                           ev, az, DryGain, delta,
-                                           src->Direct.Counter,
-                                           src->Direct.Mix.Hrtf.Params[0].Coeffs,
-                                           src->Direct.Mix.Hrtf.Params[0].Delay,
-                                           src->Direct.Mix.Hrtf.Params[0].CoeffStep,
-                                           src->Direct.Mix.Hrtf.Params[0].DelayStep);
+                    ev, az, dirfact, DryGain, delta, src->Direct.Counter,
+                    src->Direct.Mix.Hrtf.Params[0].Coeffs, src->Direct.Mix.Hrtf.Params[0].Delay,
+                    src->Direct.Mix.Hrtf.Params[0].CoeffStep, src->Direct.Mix.Hrtf.Params[0].DelayStep
+                );
                 src->Direct.Counter = counter;
                 src->Direct.Mix.Hrtf.Gain = DryGain;
                 src->Direct.Mix.Hrtf.Dir[0] = Position[0];
@@ -942,7 +944,7 @@ ALvoid CalcSourceParams(ALactivesource *src, const ALCcontext *ALContext)
         else
         {
             /* Get the initial (static) HRIR coefficients and delays. */
-            GetLerpedHrtfCoeffs(Device->Hrtf, ev, az, DryGain,
+            GetLerpedHrtfCoeffs(Device->Hrtf, ev, az, dirfact, DryGain,
                                 src->Direct.Mix.Hrtf.Params[0].Coeffs,
                                 src->Direct.Mix.Hrtf.Params[0].Delay);
             src->Direct.Counter = 0;
@@ -968,8 +970,9 @@ ALvoid CalcSourceParams(ALactivesource *src, const ALCcontext *ALContext)
         /* Normalize the length, and compute panned gains. */
         if(Distance > FLT_EPSILON)
         {
+            ALfloat radius = ALSource->Radius;
             ALfloat Target[MaxChannels];
-            ALfloat invlen = 1.0f/Distance;
+            ALfloat invlen = 1.0f/maxf(Distance, radius);
             Position[0] *= invlen;
             Position[1] *= invlen;
             Position[2] *= invlen;
diff --git a/Alc/hrtf.c b/Alc/hrtf.c
index 7eb8c2e4..fdd3259d 100644
--- a/Alc/hrtf.c
+++ b/Alc/hrtf.c
@@ -123,7 +123,7 @@ ALfloat CalcHrtfDelta(ALfloat oldGain, ALfloat newGain, const ALfloat olddir[3],
  * increase the apparent resolution of the HRIR data set.  The coefficients
  * are also normalized and attenuated by the specified gain.
  */
-void GetLerpedHrtfCoeffs(const struct Hrtf *Hrtf, ALfloat elevation, ALfloat azimuth, ALfloat gain, ALfloat (*coeffs)[2], ALuint *delays)
+void GetLerpedHrtfCoeffs(const struct Hrtf *Hrtf, ALfloat elevation, ALfloat azimuth, ALfloat dirfact, ALfloat gain, ALfloat (*coeffs)[2], ALuint *delays)
 {
     ALuint evidx[2], azidx[2];
     ALuint lidx[4], ridx[4];
@@ -162,12 +162,12 @@ void GetLerpedHrtfCoeffs(const struct Hrtf *Hrtf, ALfloat elevation, ALfloat azi
     blend[3] = (     mu[1]) * (     mu[2]);
 
     /* Calculate the HRIR delays using linear interpolation. */
-    delays[0] = fastf2u(Hrtf->delays[lidx[0]]*blend[0] + Hrtf->delays[lidx[1]]*blend[1] +
-                        Hrtf->delays[lidx[2]]*blend[2] + Hrtf->delays[lidx[3]]*blend[3] +
-                        0.5f) << HRTFDELAY_BITS;
-    delays[1] = fastf2u(Hrtf->delays[ridx[0]]*blend[0] + Hrtf->delays[ridx[1]]*blend[1] +
-                        Hrtf->delays[ridx[2]]*blend[2] + Hrtf->delays[ridx[3]]*blend[3] +
-                        0.5f) << HRTFDELAY_BITS;
+    delays[0] = fastf2u((Hrtf->delays[lidx[0]]*blend[0] + Hrtf->delays[lidx[1]]*blend[1] +
+                         Hrtf->delays[lidx[2]]*blend[2] + Hrtf->delays[lidx[3]]*blend[3]) *
+                        dirfact + 0.5f) << HRTFDELAY_BITS;
+    delays[1] = fastf2u((Hrtf->delays[ridx[0]]*blend[0] + Hrtf->delays[ridx[1]]*blend[1] +
+                         Hrtf->delays[ridx[2]]*blend[2] + Hrtf->delays[ridx[3]]*blend[3]) *
+                        dirfact + 0.5f) << HRTFDELAY_BITS;
 
     /* Calculate the sample offsets for the HRIR indices. */
     lidx[0] *= Hrtf->irSize;
@@ -185,17 +185,26 @@ void GetLerpedHrtfCoeffs(const struct Hrtf *Hrtf, ALfloat elevation, ALfloat azi
      */
     if(gain > 0.0001f)
     {
+        ALfloat c;
+
         gain *= 1.0f/32767.0f;
-        for(i = 0;i < Hrtf->irSize;i++)
+
+        i = 0;
+        c = (Hrtf->coeffs[lidx[0]+i]*blend[0] + Hrtf->coeffs[lidx[1]+i]*blend[1] +
+             Hrtf->coeffs[lidx[2]+i]*blend[2] + Hrtf->coeffs[lidx[3]+i]*blend[3]);
+        coeffs[i][0] = lerp(1.0f, c, dirfact) * gain;
+        c = (Hrtf->coeffs[ridx[0]+i]*blend[0] + Hrtf->coeffs[ridx[1]+i]*blend[1] +
+             Hrtf->coeffs[ridx[2]+i]*blend[2] + Hrtf->coeffs[ridx[3]+i]*blend[3]);
+        coeffs[i][1] = lerp(1.0f, c, dirfact) * gain;
+
+        for(i = 1;i < Hrtf->irSize;i++)
         {
-            coeffs[i][0] = (Hrtf->coeffs[lidx[0]+i]*blend[0] +
-                            Hrtf->coeffs[lidx[1]+i]*blend[1] +
-                            Hrtf->coeffs[lidx[2]+i]*blend[2] +
-                            Hrtf->coeffs[lidx[3]+i]*blend[3]) * gain;
-            coeffs[i][1] = (Hrtf->coeffs[ridx[0]+i]*blend[0] +
-                            Hrtf->coeffs[ridx[1]+i]*blend[1] +
-                            Hrtf->coeffs[ridx[2]+i]*blend[2] +
-                            Hrtf->coeffs[ridx[3]+i]*blend[3]) * gain;
+            c = (Hrtf->coeffs[lidx[0]+i]*blend[0] + Hrtf->coeffs[lidx[1]+i]*blend[1] +
+                 Hrtf->coeffs[lidx[2]+i]*blend[2] + Hrtf->coeffs[lidx[3]+i]*blend[3]);
+            coeffs[i][0] = lerp(0.0f, c, dirfact) * gain;
+            c = (Hrtf->coeffs[ridx[0]+i]*blend[0] + Hrtf->coeffs[ridx[1]+i]*blend[1] +
+                 Hrtf->coeffs[ridx[2]+i]*blend[2] + Hrtf->coeffs[ridx[3]+i]*blend[3]);
+            coeffs[i][1] = lerp(0.0f, c, dirfact) * gain;
         }
     }
     else
@@ -215,7 +224,7 @@ void GetLerpedHrtfCoeffs(const struct Hrtf *Hrtf, ALfloat elevation, ALfloat azi
  * specified gain.  Stepping resolution and count is determined using the
  * given delta factor between 0.0 and 1.0.
  */
-ALuint GetMovingHrtfCoeffs(const struct Hrtf *Hrtf, ALfloat elevation, ALfloat azimuth, ALfloat gain, ALfloat delta, ALint counter, ALfloat (*coeffs)[2], ALuint *delays, ALfloat (*coeffStep)[2], ALint *delayStep)
+ALuint GetMovingHrtfCoeffs(const struct Hrtf *Hrtf, ALfloat elevation, ALfloat azimuth, ALfloat dirfact, ALfloat gain, ALfloat delta, ALint counter, ALfloat (*coeffs)[2], ALuint *delays, ALfloat (*coeffStep)[2], ALint *delayStep)
 {
     ALuint evidx[2], azidx[2];
     ALuint lidx[4], ridx[4];
@@ -266,12 +275,12 @@ ALuint GetMovingHrtfCoeffs(const struct Hrtf *Hrtf, ALfloat elevation, ALfloat a
     left = (ALfloat)(delays[0] - (delayStep[0] * counter));
     right = (ALfloat)(delays[1] - (delayStep[1] * counter));
 
-    delays[0] = fastf2u(Hrtf->delays[lidx[0]]*blend[0] + Hrtf->delays[lidx[1]]*blend[1] +
-                        Hrtf->delays[lidx[2]]*blend[2] + Hrtf->delays[lidx[3]]*blend[3] +
-                        0.5f) << HRTFDELAY_BITS;
-    delays[1] = fastf2u(Hrtf->delays[ridx[0]]*blend[0] + Hrtf->delays[ridx[1]]*blend[1] +
-                        Hrtf->delays[ridx[2]]*blend[2] + Hrtf->delays[ridx[3]]*blend[3] +
-                        0.5f) << HRTFDELAY_BITS;
+    delays[0] = fastf2u((Hrtf->delays[lidx[0]]*blend[0] + Hrtf->delays[lidx[1]]*blend[1] +
+                         Hrtf->delays[lidx[2]]*blend[2] + Hrtf->delays[lidx[3]]*blend[3]) *
+                        dirfact + 0.5f) << HRTFDELAY_BITS;
+    delays[1] = fastf2u((Hrtf->delays[ridx[0]]*blend[0] + Hrtf->delays[ridx[1]]*blend[1] +
+                         Hrtf->delays[ridx[2]]*blend[2] + Hrtf->delays[ridx[3]]*blend[3]) *
+                        dirfact + 0.5f) << HRTFDELAY_BITS;
 
     delayStep[0] = fastf2i(step * (delays[0] - left));
     delayStep[1] = fastf2i(step * (delays[1] - right));
@@ -294,20 +303,35 @@ ALuint GetMovingHrtfCoeffs(const struct Hrtf *Hrtf, ALfloat elevation, ALfloat a
      */
     if(gain > 0.0001f)
     {
+        ALfloat c;
+
         gain *= 1.0f/32767.0f;
-        for(i = 0;i < Hrtf->irSize;i++)
+
+        i = 0;
+        left = coeffs[i][0] - (coeffStep[i][0] * counter);
+        right = coeffs[i][1] - (coeffStep[i][1] * counter);
+
+        c = (Hrtf->coeffs[lidx[0]+i]*blend[0] + Hrtf->coeffs[lidx[1]+i]*blend[1] +
+             Hrtf->coeffs[lidx[2]+i]*blend[2] + Hrtf->coeffs[lidx[3]+i]*blend[3]);
+        coeffs[i][0] = lerp(0.0f, c, dirfact) * gain;
+        c = (Hrtf->coeffs[ridx[0]+i]*blend[0] + Hrtf->coeffs[ridx[1]+i]*blend[1] +
+             Hrtf->coeffs[ridx[2]+i]*blend[2] + Hrtf->coeffs[ridx[3]+i]*blend[3]);
+        coeffs[i][1] = lerp(0.0f, c, dirfact) * gain;
+
+        coeffStep[i][0] = step * (coeffs[i][0] - left);
+        coeffStep[i][1] = step * (coeffs[i][1] - right);
+
+        for(i = 1;i < Hrtf->irSize;i++)
         {
             left = coeffs[i][0] - (coeffStep[i][0] * counter);
             right = coeffs[i][1] - (coeffStep[i][1] * counter);
 
-            coeffs[i][0] = (Hrtf->coeffs[lidx[0]+i]*blend[0] +
-                            Hrtf->coeffs[lidx[1]+i]*blend[1] +
-                            Hrtf->coeffs[lidx[2]+i]*blend[2] +
-                            Hrtf->coeffs[lidx[3]+i]*blend[3]) * gain;
-            coeffs[i][1] = (Hrtf->coeffs[ridx[0]+i]*blend[0] +
-                            Hrtf->coeffs[ridx[1]+i]*blend[1] +
-                            Hrtf->coeffs[ridx[2]+i]*blend[2] +
-                            Hrtf->coeffs[ridx[3]+i]*blend[3]) * gain;
+            c = (Hrtf->coeffs[lidx[0]+i]*blend[0] + Hrtf->coeffs[lidx[1]+i]*blend[1] +
+                 Hrtf->coeffs[lidx[2]+i]*blend[2] + Hrtf->coeffs[lidx[3]+i]*blend[3]);
+            coeffs[i][0] = lerp(1.0f, c, dirfact) * gain;
+            c = (Hrtf->coeffs[ridx[0]+i]*blend[0] + Hrtf->coeffs[ridx[1]+i]*blend[1] +
+                 Hrtf->coeffs[ridx[2]+i]*blend[2] + Hrtf->coeffs[ridx[3]+i]*blend[3]);
+            coeffs[i][1] = lerp(1.0f, c, dirfact) * gain;
 
             coeffStep[i][0] = step * (coeffs[i][0] - left);
             coeffStep[i][1] = step * (coeffs[i][1] - right);
diff --git a/Alc/hrtf.h b/Alc/hrtf.h
index 488c81d9..938bf552 100644
--- a/Alc/hrtf.h
+++ b/Alc/hrtf.h
@@ -22,7 +22,7 @@ void FreeHrtfs(void);
 
 ALuint GetHrtfIrSize(const struct Hrtf *Hrtf);
 ALfloat CalcHrtfDelta(ALfloat oldGain, ALfloat newGain, const ALfloat olddir[3], const ALfloat newdir[3]);
-void GetLerpedHrtfCoeffs(const struct Hrtf *Hrtf, ALfloat elevation, ALfloat azimuth, ALfloat gain, ALfloat (*coeffs)[2], ALuint *delays);
-ALuint GetMovingHrtfCoeffs(const struct Hrtf *Hrtf, ALfloat elevation, ALfloat azimuth, ALfloat gain, ALfloat delta, ALint counter, ALfloat (*coeffs)[2], ALuint *delays, ALfloat (*coeffStep)[2], ALint *delayStep);
+void GetLerpedHrtfCoeffs(const struct Hrtf *Hrtf, ALfloat elevation, ALfloat azimuth, ALfloat dirfact, ALfloat gain, ALfloat (*coeffs)[2], ALuint *delays);
+ALuint GetMovingHrtfCoeffs(const struct Hrtf *Hrtf, ALfloat elevation, ALfloat azimuth, ALfloat dirfact, ALfloat gain, ALfloat delta, ALint counter, ALfloat (*coeffs)[2], ALuint *delays, ALfloat (*coeffStep)[2], ALint *delayStep);
 
 #endif /* ALC_HRTF_H */