mirror of https://github.com/axmolengine/axmol.git
102 lines
3.0 KiB
C
102 lines
3.0 KiB
C
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#ifndef CORE_MIXER_H
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#define CORE_MIXER_H
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#include <array>
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#include <cmath>
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#include <stddef.h>
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#include <type_traits>
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#include "alspan.h"
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#include "ambidefs.h"
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#include "bufferline.h"
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#include "devformat.h"
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struct MixParams;
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using MixerFunc = void(*)(const al::span<const float> InSamples,
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const al::span<FloatBufferLine> OutBuffer, float *CurrentGains, const float *TargetGains,
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const size_t Counter, const size_t OutPos);
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extern MixerFunc MixSamples;
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/**
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* Calculates ambisonic encoder coefficients using the X, Y, and Z direction
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* components, which must represent a normalized (unit length) vector, and the
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* spread is the angular width of the sound (0...tau).
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*
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* NOTE: The components use ambisonic coordinates. As a result:
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*
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* Ambisonic Y = OpenAL -X
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* Ambisonic Z = OpenAL Y
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* Ambisonic X = OpenAL -Z
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*
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* The components are ordered such that OpenAL's X, Y, and Z are the first,
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* second, and third parameters respectively -- simply negate X and Z.
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*/
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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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* CalcDirectionCoeffs
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*
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* Calculates ambisonic coefficients based on an OpenAL direction vector. The
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* vector must be normalized (unit length), and the spread is the angular width
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* of the sound (0...tau).
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*/
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inline std::array<float,MaxAmbiChannels> CalcDirectionCoeffs(const float (&dir)[3],
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const float spread)
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{
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/* Convert from OpenAL coords to Ambisonics. */
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return CalcAmbiCoeffs(-dir[0], dir[1], -dir[2], spread);
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}
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/**
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* CalcAngleCoeffs
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*
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* Calculates ambisonic coefficients based on azimuth and elevation. The
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* azimuth and elevation parameters are in radians, going right and up
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* respectively.
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*/
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inline std::array<float,MaxAmbiChannels> CalcAngleCoeffs(const float azimuth,
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const float elevation, const float spread)
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{
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const float x{-std::sin(azimuth) * std::cos(elevation)};
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const float y{ std::sin(elevation)};
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const float z{ std::cos(azimuth) * std::cos(elevation)};
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return CalcAmbiCoeffs(x, y, z, spread);
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}
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/**
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* ComputePanGains
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*
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* Computes panning gains using the given channel decoder coefficients and the
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* pre-calculated direction or angle coefficients. For B-Format sources, the
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* coeffs are a 'slice' of a transform matrix for the input channel, used to
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* scale and orient the sound samples.
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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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/** Helper to set an identity/pass-through panning for ambisonic mixing (3D input). */
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template<typename T, typename I, typename F>
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auto SetAmbiPanIdentity(T iter, I count, F func) -> std::enable_if_t<std::is_integral<I>::value>
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{
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if(count < 1) return;
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std::array<float,MaxAmbiChannels> coeffs{{1.0f}};
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func(*iter, coeffs);
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++iter;
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for(I i{1};i < count;++i,++iter)
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{
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coeffs[i-1] = 0.0f;
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coeffs[i ] = 1.0f;
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func(*iter, coeffs);
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}
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}
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#endif /* CORE_MIXER_H */
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