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/*************************************************************************** |
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* * |
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* Copyright (C) 2005 - 2019 Christian Schoenebeck * |
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* * |
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* This library is free software; you can redistribute it and/or modify * |
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* it under the terms of the GNU General Public License as published by * |
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* the Free Software Foundation; either version 2 of the License, or * |
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* (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 * |
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* GNU General Public License for more details. * |
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* * |
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* You should have received a copy of the GNU General Public License * |
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* along with this library; if not, write to the Free Software * |
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, * |
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* MA 02111-1307 USA * |
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***************************************************************************/ |
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|
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#ifndef __LS_LFOTRIANGLEDIHARMONIC_H__ |
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#define __LS_LFOTRIANGLEDIHARMONIC_H__ |
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|
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#include "LFOBase.h" |
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|
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// amplitue of 2nd harmonic (to approximate the triangular wave) |
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#define AMP2 -0.11425509f |
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|
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namespace LinuxSampler { |
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|
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/** @brief Triangle LFO (di-harmonic implementation) |
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* |
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* This is a triangle Low Frequency Oscillator implementation which uses |
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* a di-harmonic solution. This means it sums up two harmonics |
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* (sinusoids) to approximate a triangular wave. |
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* |
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* @deprecated This class will probably be removed in future. Reason: The |
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* resulting wave form is not similar enough to a triangular wave. to |
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* achieve a more appropriate triangular wave form, this class would need |
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* to use more harmonics, but that in turn would make runtime performance of |
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* this class even worse. And since it currently seems to perform worst |
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* already among all triangular wave implementations on all known |
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* architectures, doing that required harmonics change currently does not |
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* make sense. Furthermore the detailed behaviour of the other triangular |
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* LFO implementations had been fixed in the meantime; this one not. |
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*/ |
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template<LFO::range_type_t RANGE> |
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class DEPRECATED_API LFOTriangleDiHarmonic : public LFOBase<RANGE> { |
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public: |
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|
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/** |
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* Constructor |
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* |
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* @param Max - maximum value of the output levels |
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*/ |
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LFOTriangleDiHarmonic(float Max) : LFOBase<RANGE>::LFOBase(Max) { |
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} |
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|
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/** |
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* Calculates exactly one sample point of the LFO wave. |
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* |
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* @returns next LFO level |
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*/ |
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inline float render() { |
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real1 -= c1 * imag1; |
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imag1 += c1 * real1; |
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real2 -= c2 * imag2; |
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imag2 += c2 * real2; |
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if (RANGE == LFO::range_unsigned) |
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return (real1 + real2 * AMP2) * normalizer + offset; |
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else /* signed range */ |
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return (real1 + real2 * AMP2) * normalizer; |
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} |
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|
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/** |
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* Update LFO depth with a new external controller value. |
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* |
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* @param ExtControlValue - new external controller value |
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*/ |
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inline void updateByMIDICtrlValue(const uint16_t& ExtControlValue) { |
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this->ExtControlValue = ExtControlValue; |
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|
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const float max = (this->InternalDepth + ExtControlValue * this->ExtControlDepthCoeff) * this->ScriptDepthFactor; |
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if (RANGE == LFO::range_unsigned) { |
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const float harmonicCompensation = 1.0f + fabsf(AMP2); // to compensate the compensation ;) (see trigger()) |
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normalizer = max * 0.5f; |
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offset = normalizer * harmonicCompensation; |
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} else { // signed range |
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normalizer = max; |
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} |
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} |
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|
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/** |
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* Will be called by the voice when the key / voice was triggered. |
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* |
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* @param Frequency - frequency of the oscillator in Hz |
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* @param StartLevel - on which level the wave should start |
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* @param InternalDepth - firm, internal oscillator amplitude |
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* @param ExtControlDepth - defines how strong the external MIDI |
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* controller has influence on the |
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* oscillator amplitude |
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* @param FlipPhase - inverts the oscillator wave against |
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* a horizontal axis |
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* @param SampleRate - current sample rate of the engines |
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* audio output signal |
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*/ |
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void trigger(float Frequency, LFO::start_level_t StartLevel, uint16_t InternalDepth, uint16_t ExtControlDepth, bool FlipPhase, unsigned int SampleRate) { |
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this->Frequency = Frequency; |
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this->ScriptFrequencyFactor = this->ScriptDepthFactor = 1.f; // reset for new voice |
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const float harmonicCompensation = 1.0f + fabsf(AMP2); // to compensate the 2nd harmonic's amplitude overhead |
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this->InternalDepth = (InternalDepth / 1200.0f) * this->Max / harmonicCompensation; |
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this->ExtControlDepthCoeff = (((float) ExtControlDepth / 1200.0f) / 127.0f) * this->Max / harmonicCompensation; |
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this->pFinalDepth = NULL; |
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this->pFinalFrequency = NULL; |
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|
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const float freq = Frequency * this->ScriptFrequencyFactor; |
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c1 = 2.0f * M_PI * freq / (float) SampleRate; |
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c2 = 2.0f * M_PI * freq / (float) SampleRate * 3.0f; |
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|
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double phi; // phase displacement |
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switch (StartLevel) { |
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case LFO::start_level_mid: |
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//FIXME: direct jumping to 90� and 270� doesn't work out due to numeric accuracy problems (causes wave deformation) |
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//phi = (FlipPhase) ? 0.5 * M_PI : 1.5 * M_PI; // 90� or 270� |
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//break; |
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case LFO::start_level_max: |
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phi = (FlipPhase) ? M_PI : 0.0; // 180� or 0� |
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break; |
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case LFO::start_level_min: |
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phi = (FlipPhase) ? 0.0 : M_PI; // 0� or 180� |
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break; |
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} |
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real1 = real2 = cos(phi); |
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imag1 = imag2 = sin(phi); |
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} |
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|
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/** |
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* Should be invoked after the LFO is triggered with StartLevel |
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* start_level_min. |
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* @param phase From 0 to 360 degrees. |
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*/ |
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void setPhase(float phase) { |
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if (phase < 0) phase = 0; |
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if (phase > 360) phase = 360; |
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phase /= 360.0f; |
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|
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// FIXME: too heavy? |
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float steps = 1.0f / (c1 / (2.0f * M_PI)); // number of steps for one cycle |
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steps *= phase + 0.25f; |
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for (int i = 0; i < steps; i++) render(); |
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} |
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|
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void setFrequency(float Frequency, unsigned int SampleRate) { |
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this->Frequency = Frequency; |
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const float freq = Frequency * this->ScriptFrequencyFactor; |
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c1 = 2.0f * M_PI * freq / (float) SampleRate; |
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c2 = 2.0f * M_PI * freq / (float) SampleRate * 3.0f; |
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} |
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|
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void setScriptDepthFactor(float factor, bool isFinal) { |
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this->ScriptDepthFactor = factor; |
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// set or reset this script depth parameter to be the sole |
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// source for the LFO depth |
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if (isFinal && !this->pFinalDepth) |
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this->pFinalDepth = &this->ScriptDepthFactor; |
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else if (!isFinal && this->pFinalDepth == &this->ScriptDepthFactor) |
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this->pFinalDepth = NULL; |
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// recalculate upon new depth |
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updateByMIDICtrlValue(this->ExtControlValue); |
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} |
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|
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void setScriptFrequencyFactor(float factor, unsigned int SampleRate) { |
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this->ScriptFrequencyFactor = factor; |
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// in case script frequency was set as "final" value before, |
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// reset it so that all sources are processed from now on |
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if (this->pFinalFrequency == &this->ScriptFrequencyFactor) |
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this->pFinalFrequency = NULL; |
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// recalculate upon new frequency |
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setFrequency(this->Frequency, SampleRate); |
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} |
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|
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void setScriptFrequencyFinal(float hz, unsigned int SampleRate) { |
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this->ScriptFrequencyFactor = hz; |
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// assign script's given frequency as sole source for the LFO |
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// frequency, thus ignore all other sources |
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if (!this->pFinalFrequency) |
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this->pFinalFrequency = &this->ScriptFrequencyFactor; |
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// recalculate upon new frequency |
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setFrequency(this->Frequency, SampleRate); |
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} |
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|
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private: |
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float c1; |
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float c2; |
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float real1; |
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float imag1; |
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float real2; |
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float imag2; |
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float normalizer; |
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float offset; |
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}; |
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|
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} // namespace LinuxSampler |
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|
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#endif // __LS_LFOTRIANGLEDIHARMONIC_H__ |