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222 lines
7.1 KiB
222 lines
7.1 KiB
/**
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* OpenAL cross platform audio library
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* Copyright (C) 2018 by Raul Herraiz.
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Library General Public
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* License as published by the Free Software Foundation; either
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* version 2 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Library General Public License for more details.
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*
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* You should have received a copy of the GNU Library General Public
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* License along with this library; if not, write to the
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* Free Software Foundation, Inc.,
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* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
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* Or go to http://www.gnu.org/copyleft/lgpl.html
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*/
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#include "config.h"
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#include <algorithm>
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#include <array>
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#include <cstdlib>
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#include <iterator>
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#include <utility>
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#include "alc/effects/base.h"
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#include "almalloc.h"
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#include "alnumbers.h"
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#include "alnumeric.h"
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#include "alspan.h"
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#include "core/ambidefs.h"
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#include "core/bufferline.h"
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#include "core/context.h"
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#include "core/devformat.h"
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#include "core/device.h"
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#include "core/effectslot.h"
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#include "core/mixer.h"
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#include "intrusive_ptr.h"
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namespace {
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constexpr float GainScale{31621.0f};
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constexpr float MinFreq{20.0f};
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constexpr float MaxFreq{2500.0f};
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constexpr float QFactor{5.0f};
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struct AutowahState final : public EffectState {
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/* Effect parameters */
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float mAttackRate;
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float mReleaseRate;
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float mResonanceGain;
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float mPeakGain;
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float mFreqMinNorm;
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float mBandwidthNorm;
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float mEnvDelay;
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/* Filter components derived from the envelope. */
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struct {
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float cos_w0;
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float alpha;
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} mEnv[BufferLineSize];
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struct {
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/* Effect filters' history. */
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struct {
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float z1, z2;
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} Filter;
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/* Effect gains for each output channel */
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float CurrentGains[MAX_OUTPUT_CHANNELS];
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float TargetGains[MAX_OUTPUT_CHANNELS];
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} mChans[MaxAmbiChannels];
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/* Effects buffers */
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alignas(16) float mBufferOut[BufferLineSize];
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void deviceUpdate(const DeviceBase *device, const Buffer &buffer) override;
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void update(const ContextBase *context, const EffectSlot *slot, const EffectProps *props,
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const EffectTarget target) override;
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void process(const size_t samplesToDo, const al::span<const FloatBufferLine> samplesIn,
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const al::span<FloatBufferLine> samplesOut) override;
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DEF_NEWDEL(AutowahState)
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};
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void AutowahState::deviceUpdate(const DeviceBase*, const Buffer&)
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{
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/* (Re-)initializing parameters and clear the buffers. */
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mAttackRate = 1.0f;
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mReleaseRate = 1.0f;
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mResonanceGain = 10.0f;
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mPeakGain = 4.5f;
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mFreqMinNorm = 4.5e-4f;
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mBandwidthNorm = 0.05f;
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mEnvDelay = 0.0f;
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for(auto &e : mEnv)
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{
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e.cos_w0 = 0.0f;
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e.alpha = 0.0f;
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}
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for(auto &chan : mChans)
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{
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std::fill(std::begin(chan.CurrentGains), std::end(chan.CurrentGains), 0.0f);
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chan.Filter.z1 = 0.0f;
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chan.Filter.z2 = 0.0f;
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}
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}
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void AutowahState::update(const ContextBase *context, const EffectSlot *slot,
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const EffectProps *props, const EffectTarget target)
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{
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const DeviceBase *device{context->mDevice};
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const auto frequency = static_cast<float>(device->Frequency);
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const float ReleaseTime{clampf(props->Autowah.ReleaseTime, 0.001f, 1.0f)};
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mAttackRate = std::exp(-1.0f / (props->Autowah.AttackTime*frequency));
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mReleaseRate = std::exp(-1.0f / (ReleaseTime*frequency));
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/* 0-20dB Resonance Peak gain */
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mResonanceGain = std::sqrt(std::log10(props->Autowah.Resonance)*10.0f / 3.0f);
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mPeakGain = 1.0f - std::log10(props->Autowah.PeakGain / GainScale);
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mFreqMinNorm = MinFreq / frequency;
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mBandwidthNorm = (MaxFreq-MinFreq) / frequency;
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mOutTarget = target.Main->Buffer;
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auto set_gains = [slot,target](auto &chan, al::span<const float,MaxAmbiChannels> coeffs)
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{ ComputePanGains(target.Main, coeffs.data(), slot->Gain, chan.TargetGains); };
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SetAmbiPanIdentity(std::begin(mChans), slot->Wet.Buffer.size(), set_gains);
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}
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void AutowahState::process(const size_t samplesToDo,
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const al::span<const FloatBufferLine> samplesIn, const al::span<FloatBufferLine> samplesOut)
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{
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const float attack_rate{mAttackRate};
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const float release_rate{mReleaseRate};
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const float res_gain{mResonanceGain};
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const float peak_gain{mPeakGain};
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const float freq_min{mFreqMinNorm};
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const float bandwidth{mBandwidthNorm};
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float env_delay{mEnvDelay};
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for(size_t i{0u};i < samplesToDo;i++)
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{
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float w0, sample, a;
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/* Envelope follower described on the book: Audio Effects, Theory,
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* Implementation and Application.
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*/
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sample = peak_gain * std::fabs(samplesIn[0][i]);
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a = (sample > env_delay) ? attack_rate : release_rate;
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env_delay = lerpf(sample, env_delay, a);
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/* Calculate the cos and alpha components for this sample's filter. */
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w0 = minf((bandwidth*env_delay + freq_min), 0.46f) * (al::numbers::pi_v<float>*2.0f);
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mEnv[i].cos_w0 = std::cos(w0);
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mEnv[i].alpha = std::sin(w0)/(2.0f * QFactor);
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}
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mEnvDelay = env_delay;
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auto chandata = std::addressof(mChans[0]);
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for(const auto &insamples : samplesIn)
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{
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/* This effectively inlines BiquadFilter_setParams for a peaking
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* filter and BiquadFilter_processC. The alpha and cosine components
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* for the filter coefficients were previously calculated with the
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* envelope. Because the filter changes for each sample, the
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* coefficients are transient and don't need to be held.
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*/
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float z1{chandata->Filter.z1};
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float z2{chandata->Filter.z2};
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for(size_t i{0u};i < samplesToDo;i++)
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{
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const float alpha{mEnv[i].alpha};
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const float cos_w0{mEnv[i].cos_w0};
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float input, output;
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float a[3], b[3];
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b[0] = 1.0f + alpha*res_gain;
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b[1] = -2.0f * cos_w0;
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b[2] = 1.0f - alpha*res_gain;
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a[0] = 1.0f + alpha/res_gain;
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a[1] = -2.0f * cos_w0;
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a[2] = 1.0f - alpha/res_gain;
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input = insamples[i];
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output = input*(b[0]/a[0]) + z1;
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z1 = input*(b[1]/a[0]) - output*(a[1]/a[0]) + z2;
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z2 = input*(b[2]/a[0]) - output*(a[2]/a[0]);
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mBufferOut[i] = output;
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}
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chandata->Filter.z1 = z1;
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chandata->Filter.z2 = z2;
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/* Now, mix the processed sound data to the output. */
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MixSamples({mBufferOut, samplesToDo}, samplesOut, chandata->CurrentGains,
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chandata->TargetGains, samplesToDo, 0);
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++chandata;
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}
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}
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struct AutowahStateFactory final : public EffectStateFactory {
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al::intrusive_ptr<EffectState> create() override
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{ return al::intrusive_ptr<EffectState>{new AutowahState{}}; }
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};
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} // namespace
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EffectStateFactory *AutowahStateFactory_getFactory()
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{
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static AutowahStateFactory AutowahFactory{};
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return &AutowahFactory;
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}
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