diff options
| -rw-r--r-- | Alc/hrtf.c | 107 |
1 files changed, 82 insertions, 25 deletions
@@ -67,20 +67,28 @@ static struct HrtfEntry *LoadedHrtfs = NULL; * will return an index between 0 and (evcount - 1). Assumes the FPU is in * round-to-zero mode. */ -static ALsizei CalcEvIndex(ALsizei evcount, ALfloat ev) +static ALsizei CalcEvIndex(ALsizei evcount, ALfloat ev, ALfloat *mu) { - ev = (F_PI_2 + ev) * (evcount-1) / F_PI; - return mini(fastf2i(ev + 0.5f), evcount-1); + ALsizei idx; + ev = (F_PI_2+ev) * (evcount-1) / F_PI; + idx = mini(fastf2i(ev), evcount-1); + + *mu = ev - idx; + return idx; } /* Calculate the azimuth index given the polar azimuth in radians. This will * return an index between 0 and (azcount - 1). Assumes the FPU is in round-to- * zero mode. */ -static ALsizei CalcAzIndex(ALsizei azcount, ALfloat az) +static ALsizei CalcAzIndex(ALsizei azcount, ALfloat az, ALfloat *mu) { - az = (F_TAU + az) * azcount / F_TAU; - return fastf2i(az + 0.5f) % azcount; + ALsizei idx; + az = (F_TAU+az) * azcount / F_TAU; + + idx = fastf2i(az) % azcount; + *mu = az - floorf(az); + return idx; } /* Calculates static HRIR coefficients and delays for the given polar elevation @@ -88,38 +96,87 @@ static ALsizei CalcAzIndex(ALsizei azcount, ALfloat az) */ void GetHrtfCoeffs(const struct Hrtf *Hrtf, ALfloat elevation, ALfloat azimuth, ALfloat spread, ALfloat (*coeffs)[2], ALsizei *delays) { - ALsizei evidx, azidx, idx; + ALsizei evidx, azidx, idx[4]; ALsizei evoffset; + ALfloat emu, amu[2]; + ALfloat blend[4]; ALfloat dirfact; - ALsizei i; + ALsizei i, c; dirfact = 1.0f - (spread / F_TAU); - /* Claculate elevation index. */ - evidx = CalcEvIndex(Hrtf->evCount, elevation); + /* Claculate the lower elevation index. */ + evidx = CalcEvIndex(Hrtf->evCount, elevation, &emu); evoffset = Hrtf->evOffset[evidx]; - /* Calculate azimuth index. */ - azidx = CalcAzIndex(Hrtf->azCount[evidx], azimuth); + /* Calculate lower azimuth index. */ + azidx= CalcAzIndex(Hrtf->azCount[evidx], azimuth, &amu[0]); - /* Calculate the HRIR indices for left and right channels. */ - idx = evoffset + azidx; + /* Calculate the lower HRIR indices. */ + idx[0] = evoffset + azidx; + idx[1] = evoffset + ((azidx+1) % Hrtf->azCount[evidx]); + if(evidx < Hrtf->evCount-1) + { + /* Increment elevation to the next (upper) index. */ + evidx++; + evoffset = Hrtf->evOffset[evidx]; - /* Calculate the HRIR delays. */ - delays[0] = fastf2i(Hrtf->delays[idx][0]*dirfact + 0.5f); - delays[1] = fastf2i(Hrtf->delays[idx][1]*dirfact + 0.5f); + /* Calculate upper azimuth index. */ + azidx = CalcAzIndex(Hrtf->azCount[evidx], azimuth, &amu[1]); - /* Calculate the sample offsets for the HRIR indices. */ - idx *= Hrtf->irSize; + /* Calculate the upper HRIR indices. */ + idx[2] = evoffset + azidx; + idx[3] = evoffset + ((azidx+1) % Hrtf->azCount[evidx]); + } + else + { + /* If the lower elevation is the top index, the upper elevation is the + * same as the lower. + */ + amu[1] = amu[0]; + idx[2] = idx[0]; + idx[3] = idx[1]; + } - /* Calculate the normalized and attenuated HRIR coefficients. */ - i = 0; - coeffs[i][0] = lerp(PassthruCoeff, Hrtf->coeffs[idx+i][0], dirfact); - coeffs[i][1] = lerp(PassthruCoeff, Hrtf->coeffs[idx+i][1], dirfact); + /* Calculate bilinear blending weights, attenuated according to the + * directional panning factor. + */ + blend[0] = (1.0f-emu) * (1.0f-amu[0]) * dirfact; + blend[1] = (1.0f-emu) * ( amu[0]) * dirfact; + blend[2] = ( emu) * (1.0f-amu[1]) * dirfact; + blend[3] = ( emu) * ( amu[1]) * dirfact; + + /* Calculate the blended HRIR delays. */ + delays[0] = fastf2i( + Hrtf->delays[idx[0]][0]*blend[0] + Hrtf->delays[idx[1]][0]*blend[1] + + Hrtf->delays[idx[2]][0]*blend[2] + Hrtf->delays[idx[3]][0]*blend[3] + 0.5f + ); + delays[1] = fastf2i( + Hrtf->delays[idx[0]][1]*blend[0] + Hrtf->delays[idx[1]][1]*blend[1] + + Hrtf->delays[idx[2]][1]*blend[2] + Hrtf->delays[idx[3]][1]*blend[3] + 0.5f + ); + + /* Calculate the sample offsets for the HRIR indices. */ + idx[0] *= Hrtf->irSize; + idx[1] *= Hrtf->irSize; + idx[2] *= Hrtf->irSize; + idx[3] *= Hrtf->irSize; + + /* Calculate the blended HRIR coefficients. */ + coeffs[0][0] = PassthruCoeff * (1.0f-dirfact); + coeffs[0][1] = PassthruCoeff * (1.0f-dirfact); for(i = 1;i < Hrtf->irSize;i++) { - coeffs[i][0] = Hrtf->coeffs[idx+i][0] * dirfact; - coeffs[i][1] = Hrtf->coeffs[idx+i][1] * dirfact; + coeffs[i][0] = 0.0f; + coeffs[i][1] = 0.0f; + } + for(c = 0;c < 4;c++) + { + for(i = 0;i < Hrtf->irSize;i++) + { + coeffs[i][0] += Hrtf->coeffs[idx[c]+i][0] * blend[c]; + coeffs[i][1] += Hrtf->coeffs[idx[c]+i][1] * blend[c]; + } } } |