mirror of https://github.com/axmolengine/axmol.git
127 lines
4.9 KiB
C++
127 lines
4.9 KiB
C++
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#include "config.h"
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#include "mixer.h"
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#include <cmath>
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#include "devformat.h"
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#include "device.h"
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#include "math_defs.h"
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#include "mixer/defs.h"
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struct CTag;
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MixerFunc MixSamples{Mix_<CTag>};
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std::array<float,MaxAmbiChannels> CalcAmbiCoeffs(const float y, const float z, const float x,
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const float spread)
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{
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std::array<float,MaxAmbiChannels> coeffs;
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/* Zeroth-order */
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coeffs[0] = 1.0f; /* ACN 0 = 1 */
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/* First-order */
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coeffs[1] = 1.732050808f * y; /* ACN 1 = sqrt(3) * Y */
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coeffs[2] = 1.732050808f * z; /* ACN 2 = sqrt(3) * Z */
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coeffs[3] = 1.732050808f * x; /* ACN 3 = sqrt(3) * X */
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/* Second-order */
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const float xx{x*x}, yy{y*y}, zz{z*z}, xy{x*y}, yz{y*z}, xz{x*z};
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coeffs[4] = 3.872983346f * xy; /* ACN 4 = sqrt(15) * X * Y */
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coeffs[5] = 3.872983346f * yz; /* ACN 5 = sqrt(15) * Y * Z */
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coeffs[6] = 1.118033989f * (3.0f*zz - 1.0f); /* ACN 6 = sqrt(5)/2 * (3*Z*Z - 1) */
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coeffs[7] = 3.872983346f * xz; /* ACN 7 = sqrt(15) * X * Z */
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coeffs[8] = 1.936491673f * (xx - yy); /* ACN 8 = sqrt(15)/2 * (X*X - Y*Y) */
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/* Third-order */
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coeffs[9] = 2.091650066f * (y*(3.0f*xx - yy)); /* ACN 9 = sqrt(35/8) * Y * (3*X*X - Y*Y) */
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coeffs[10] = 10.246950766f * (z*xy); /* ACN 10 = sqrt(105) * Z * X * Y */
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coeffs[11] = 1.620185175f * (y*(5.0f*zz - 1.0f)); /* ACN 11 = sqrt(21/8) * Y * (5*Z*Z - 1) */
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coeffs[12] = 1.322875656f * (z*(5.0f*zz - 3.0f)); /* ACN 12 = sqrt(7)/2 * Z * (5*Z*Z - 3) */
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coeffs[13] = 1.620185175f * (x*(5.0f*zz - 1.0f)); /* ACN 13 = sqrt(21/8) * X * (5*Z*Z - 1) */
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coeffs[14] = 5.123475383f * (z*(xx - yy)); /* ACN 14 = sqrt(105)/2 * Z * (X*X - Y*Y) */
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coeffs[15] = 2.091650066f * (x*(xx - 3.0f*yy)); /* ACN 15 = sqrt(35/8) * X * (X*X - 3*Y*Y) */
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/* Fourth-order */
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/* ACN 16 = sqrt(35)*3/2 * X * Y * (X*X - Y*Y) */
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/* ACN 17 = sqrt(35/2)*3/2 * (3*X*X - Y*Y) * Y * Z */
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/* ACN 18 = sqrt(5)*3/2 * X * Y * (7*Z*Z - 1) */
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/* ACN 19 = sqrt(5/2)*3/2 * Y * Z * (7*Z*Z - 3) */
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/* ACN 20 = 3/8 * (35*Z*Z*Z*Z - 30*Z*Z + 3) */
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/* ACN 21 = sqrt(5/2)*3/2 * X * Z * (7*Z*Z - 3) */
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/* ACN 22 = sqrt(5)*3/4 * (X*X - Y*Y) * (7*Z*Z - 1) */
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/* ACN 23 = sqrt(35/2)*3/2 * (X*X - 3*Y*Y) * X * Z */
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/* ACN 24 = sqrt(35)*3/8 * (X*X*X*X - 6*X*X*Y*Y + Y*Y*Y*Y) */
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if(spread > 0.0f)
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{
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/* Implement the spread by using a spherical source that subtends the
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* angle spread. See:
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* http://www.ppsloan.org/publications/StupidSH36.pdf - Appendix A3
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*
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* When adjusted for N3D normalization instead of SN3D, these
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* calculations are:
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*
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* ZH0 = -sqrt(pi) * (-1+ca);
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* ZH1 = 0.5*sqrt(pi) * sa*sa;
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* ZH2 = -0.5*sqrt(pi) * ca*(-1+ca)*(ca+1);
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* ZH3 = -0.125*sqrt(pi) * (-1+ca)*(ca+1)*(5*ca*ca - 1);
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* ZH4 = -0.125*sqrt(pi) * ca*(-1+ca)*(ca+1)*(7*ca*ca - 3);
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* ZH5 = -0.0625*sqrt(pi) * (-1+ca)*(ca+1)*(21*ca*ca*ca*ca - 14*ca*ca + 1);
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*
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* The gain of the source is compensated for size, so that the
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* loudness doesn't depend on the spread. Thus:
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*
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* ZH0 = 1.0f;
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* ZH1 = 0.5f * (ca+1.0f);
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* ZH2 = 0.5f * (ca+1.0f)*ca;
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* ZH3 = 0.125f * (ca+1.0f)*(5.0f*ca*ca - 1.0f);
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* ZH4 = 0.125f * (ca+1.0f)*(7.0f*ca*ca - 3.0f)*ca;
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* ZH5 = 0.0625f * (ca+1.0f)*(21.0f*ca*ca*ca*ca - 14.0f*ca*ca + 1.0f);
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*/
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const float ca{std::cos(spread * 0.5f)};
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/* Increase the source volume by up to +3dB for a full spread. */
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const float scale{std::sqrt(1.0f + spread/al::MathDefs<float>::Tau())};
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const float ZH0_norm{scale};
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const float ZH1_norm{scale * 0.5f * (ca+1.f)};
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const float ZH2_norm{scale * 0.5f * (ca+1.f)*ca};
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const float ZH3_norm{scale * 0.125f * (ca+1.f)*(5.f*ca*ca-1.f)};
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/* Zeroth-order */
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coeffs[0] *= ZH0_norm;
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/* First-order */
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coeffs[1] *= ZH1_norm;
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coeffs[2] *= ZH1_norm;
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coeffs[3] *= ZH1_norm;
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/* Second-order */
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coeffs[4] *= ZH2_norm;
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coeffs[5] *= ZH2_norm;
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coeffs[6] *= ZH2_norm;
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coeffs[7] *= ZH2_norm;
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coeffs[8] *= ZH2_norm;
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/* Third-order */
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coeffs[9] *= ZH3_norm;
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coeffs[10] *= ZH3_norm;
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coeffs[11] *= ZH3_norm;
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coeffs[12] *= ZH3_norm;
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coeffs[13] *= ZH3_norm;
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coeffs[14] *= ZH3_norm;
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coeffs[15] *= ZH3_norm;
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}
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return coeffs;
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}
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void ComputePanGains(const MixParams *mix, const float*RESTRICT coeffs, const float ingain,
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const al::span<float,MAX_OUTPUT_CHANNELS> gains)
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{
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auto ambimap = mix->AmbiMap.cbegin();
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auto iter = std::transform(ambimap, ambimap+mix->Buffer.size(), gains.begin(),
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[coeffs,ingain](const BFChannelConfig &chanmap) noexcept -> float
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{ return chanmap.Scale * coeffs[chanmap.Index] * ingain; }
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);
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std::fill(iter, gains.end(), 0.0f);
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}
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