diff options
| -rw-r--r-- | Alc/panning.c | 27 |
1 files changed, 18 insertions, 9 deletions
diff --git a/Alc/panning.c b/Alc/panning.c index bfdd47e2..619b89c6 100644 --- a/Alc/panning.c +++ b/Alc/panning.c @@ -143,17 +143,26 @@ void CalcDirectionCoeffs(const ALfloat dir[3], ALfloat spread, ALfloat coeffs[MA * angle spread. See: * http://www.ppsloan.org/publications/StupidSH36.pdf - Appendix A3 * - * The gain of the source is compensated for size, so that the - * loundness doesn't depend on the spread. + * When adjusted for N3D normalization instead of SN3D, these + * calculations are: + * + * ZH0 = -sqrt(pi) * (-1+ca); + * ZH1 = 0.5*sqrt(pi) * sa*sa; + * ZH2 = -0.5*sqrt(pi) * ca*(-1+ca)*(ca+1); + * ZH3 = -0.125*sqrt(pi) * (-1+ca)*(ca+1)*(5*ca*ca - 1); + * ZH4 = -0.125*sqrt(pi) * ca*(-1+ca)*(ca+1)*(7*ca*ca - 3); + * ZH5 = -0.0625*sqrt(pi) * (-1+ca)*(ca+1)*(21*ca*ca*ca*ca - 14*ca*ca + 1); * - * ZH0 = (-sqrt_pi * (-1.f + ca)); - * ZH1 = ( 0.5f*sqrtf(3.f)*sqrt_pi * sa*sa); - * ZH2 = (-0.5f*sqrtf(5.f)*sqrt_pi * ca*(-1.f+ca)*(ca+1.f)); - * ZH3 = (-0.125f*sqrtf(7.f)*sqrt_pi * (-1.f+ca)*(ca+1.f)*(5.f*ca*ca-1.f)); - * solidangle = 2.f*F_PI*(1.f-ca) - * size_normalisation_coef = 1.f/ZH0; + * The gain of the source is compensated for size, so that the + * loundness doesn't depend on the spread. That is, the factors are + * scaled so that ZH0 remains 1 regardless of the spread. Thus: * - * This is then adjusted for N3D normalization over SN3D. + * ZH0 = 1.0f; + * ZH1 = 0.5f * (ca+1.0f); + * ZH2 = 0.5f * (ca+1.0f)*ca; + * ZH3 = 0.125f * (ca+1.0f)*(5.0f*ca*ca - 1.0f); + * ZH4 = 0.125f * (ca+1.0f)*(7.0f*ca*ca - 3.0f)*ca; + * ZH5 = 0.0625f * (ca+1.0f)*(21.0f*ca*ca*ca*ca - 14.0f*ca*ca + 1.0f); */ ALfloat ca = cosf(spread * 0.5f); |