diff options
Diffstat (limited to 'Alc')
| -rw-r--r-- | Alc/hrtf.c | 68 |
1 files changed, 42 insertions, 26 deletions
@@ -113,8 +113,8 @@ ALfloat CalcHrtfDelta(ALfloat oldGain, ALfloat newGain, const ALfloat olddir[3], void GetLerpedHrtfCoeffs(const struct Hrtf *Hrtf, ALfloat elevation, ALfloat azimuth, ALfloat gain, ALfloat (*coeffs)[2], ALuint *delays) { ALuint evidx[2], azidx[2]; - ALfloat mu[3]; ALuint lidx[4], ridx[4]; + ALfloat mu[3], blend[4]; ALuint i; // Claculate elevation indices and interpolation factor. @@ -142,6 +142,12 @@ void GetLerpedHrtfCoeffs(const struct Hrtf *Hrtf, ALfloat elevation, ALfloat azi ridx[2] = evOffset[evidx[1]] + ((azCount[evidx[1]]-azidx[0]) % azCount[evidx[1]]); ridx[3] = evOffset[evidx[1]] + ((azCount[evidx[1]]-azidx[1]) % azCount[evidx[1]]); + /* Calculate 4 blending weights for 2D bilinear interpolation */ + blend[0] = (1.0f-mu[0]) * (1.0f-mu[2]); + blend[1] = ( mu[0]) * (1.0f-mu[2]); + blend[2] = (1.0f-mu[1]) * ( mu[2]); + blend[3] = ( mu[1]) * ( mu[2]); + // Calculate the normalized and attenuated HRIR coefficients using linear // interpolation when there is enough gain to warrant it. Zero the // coefficients if gain is too low. @@ -150,12 +156,14 @@ void GetLerpedHrtfCoeffs(const struct Hrtf *Hrtf, ALfloat elevation, ALfloat azi gain *= 1.0f/32767.0f; for(i = 0;i < HRIR_LENGTH;i++) { - coeffs[i][0] = lerp(lerp(Hrtf->coeffs[lidx[0]][i], Hrtf->coeffs[lidx[1]][i], mu[0]), - lerp(Hrtf->coeffs[lidx[2]][i], Hrtf->coeffs[lidx[3]][i], mu[1]), - mu[2]) * gain; - coeffs[i][1] = lerp(lerp(Hrtf->coeffs[ridx[0]][i], Hrtf->coeffs[ridx[1]][i], mu[0]), - lerp(Hrtf->coeffs[ridx[2]][i], Hrtf->coeffs[ridx[3]][i], mu[1]), - mu[2]) * gain; + 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; } } else @@ -168,12 +176,12 @@ void GetLerpedHrtfCoeffs(const struct Hrtf *Hrtf, ALfloat elevation, ALfloat azi } // Calculate the HRIR delays using linear interpolation. - delays[0] = fastf2u(lerp(lerp(Hrtf->delays[lidx[0]], Hrtf->delays[lidx[1]], mu[0]), - lerp(Hrtf->delays[lidx[2]], Hrtf->delays[lidx[3]], mu[1]), - mu[2]) + 0.5f) << HRTFDELAY_BITS; - delays[1] = fastf2u(lerp(lerp(Hrtf->delays[ridx[0]], Hrtf->delays[ridx[1]], mu[0]), - lerp(Hrtf->delays[ridx[2]], Hrtf->delays[ridx[3]], mu[1]), - mu[2]) + 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] + + 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; } // Calculates the moving HRIR target coefficients, target delays, and @@ -186,8 +194,8 @@ ALuint GetMovingHrtfCoeffs(const struct Hrtf *Hrtf, ALfloat elevation, ALfloat a { ALuint evidx[2], azidx[2]; ALuint lidx[4], ridx[4]; + ALfloat mu[3], blend[4]; ALfloat left, right; - ALfloat mu[3]; ALfloat step; ALuint i; @@ -220,6 +228,12 @@ ALuint GetMovingHrtfCoeffs(const struct Hrtf *Hrtf, ALfloat elevation, ALfloat a delta = maxf(floorf(delta*(Hrtf->sampleRate*0.015f) + 0.5f), 1.0f); step = 1.0f / delta; + /* Calculate 4 blending weights for 2D bilinear interpolation */ + blend[0] = (1.0f-mu[0]) * (1.0f-mu[2]); + blend[1] = ( mu[0]) * (1.0f-mu[2]); + blend[2] = (1.0f-mu[1]) * ( mu[2]); + blend[3] = ( mu[1]) * ( mu[2]); + // Calculate the normalized and attenuated target HRIR coefficients using // linear interpolation when there is enough gain to warrant it. Zero // the target coefficients if gain is too low. Then calculate the @@ -233,12 +247,14 @@ ALuint GetMovingHrtfCoeffs(const struct Hrtf *Hrtf, ALfloat elevation, ALfloat a left = coeffs[i][0] - (coeffStep[i][0] * counter); right = coeffs[i][1] - (coeffStep[i][1] * counter); - coeffs[i][0] = lerp(lerp(Hrtf->coeffs[lidx[0]][i], Hrtf->coeffs[lidx[1]][i], mu[0]), - lerp(Hrtf->coeffs[lidx[2]][i], Hrtf->coeffs[lidx[3]][i], mu[1]), - mu[2]) * gain; - coeffs[i][1] = lerp(lerp(Hrtf->coeffs[ridx[0]][i], Hrtf->coeffs[ridx[1]][i], mu[0]), - lerp(Hrtf->coeffs[ridx[2]][i], Hrtf->coeffs[ridx[3]][i], mu[1]), - mu[2]) * gain; + 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; coeffStep[i][0] = step * (coeffs[i][0] - left); coeffStep[i][1] = step * (coeffs[i][1] - right); @@ -265,12 +281,12 @@ 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(lerp(lerp(Hrtf->delays[lidx[0]], Hrtf->delays[lidx[1]], mu[0]), - lerp(Hrtf->delays[lidx[2]], Hrtf->delays[lidx[3]], mu[1]), - mu[2]) + 0.5f) << HRTFDELAY_BITS; - delays[1] = fastf2u(lerp(lerp(Hrtf->delays[ridx[0]], Hrtf->delays[ridx[1]], mu[0]), - lerp(Hrtf->delays[ridx[2]], Hrtf->delays[ridx[3]], mu[1]), - mu[2]) + 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] + + 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; delayStep[0] = fastf2i(step * (delays[0] - left)); delayStep[1] = fastf2i(step * (delays[1] - right)); |