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/*************************************************************************** |
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* * |
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* LinuxSampler - modular, streaming capable sampler * |
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* * |
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* Copyright (C) 2003 by Benno Senoner and Christian Schoenebeck * |
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* * |
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* This program 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 program 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 program; 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 __LFO_H__ |
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#define __LFO_H__ |
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|
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#include "global.h" |
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#include "rtmath.h" |
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#include "modulationsystem.h" |
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|
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/** |
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* Low Frequency Oscillator |
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* |
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* Synthesizes a triangular wave for arbitrary usage. This LFO class is a |
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* generalization; it takes a class as template parameter (T_Manipulator) |
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* which is actually responsible to do something with the wave levels of the |
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* oscillator. The class given with T_Manipulator has to provide a |
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* |
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* void ApplyLevel(float Level, int iSample); |
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* |
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* method. This method will be called by the LFO whenever the level of the |
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* oscillator wave changes, where parameter 'Level' is the new level of the |
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* wave and 'iSample' is the index of the corresponding sample point in the |
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* current audio fragment. |
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*/ |
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template<class T_Manipulator> |
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class LFO { |
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public: |
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|
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// *************** types *************** |
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// * |
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|
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/** |
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* Defines the position of the LFO wave within the given value range |
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* and from which value to start when the LFO is triggered. |
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*/ |
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enum propagation_t { |
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propagation_top_down, ///< Wave level starts from given max. and grows down with growing oscillator depth. |
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propagation_middle_balanced, ///< Wave level starts from the middle of the given value range and grows in both directions with growing oscillator depth. |
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propagation_bottom_up ///< Wave level starts from given min. and grows up with growing oscillator depth. |
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}; |
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|
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|
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// *************** attributes *************** |
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// * |
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|
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T_Manipulator Manipulator; ///< Instance of the specific manipulator class given by template parameter T_Manipulator. |
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uint8_t ExtController; ///< MIDI control change controller number if the LFO is controlled by an external controller, 0 otherwise. |
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|
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|
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// *************** methods *************** |
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// * |
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|
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/** |
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* Constructor |
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* |
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* @param Min - minimum value of the output level |
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* @param Max - maximum value of the output level |
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* @param Propagation - defines from which level the wave starts and which direction it grows with growing oscillator depth |
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* @param pEventPool - reference to an event pool which will be used to allocate Event objects |
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*/ |
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LFO(float Min, float Max, propagation_t Propagation, RTELMemoryPool<ModulationSystem::Event>* pEventPool) { |
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this->Propagation = Propagation; |
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this->pEvents = new RTEList<ModulationSystem::Event>(pEventPool); |
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this->ExtController = 0; |
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this->Min = Min; |
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this->Max = Max; |
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this->Range = Max - Min; |
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} |
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|
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~LFO() { |
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if (pEvents) delete pEvents; |
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} |
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|
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/** |
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* Will be called by the voice for every audio fragment to let the LFO write it's modulation changes to the synthesis parameter matrix for the current audio fragment. |
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* |
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* @param Samples - total number of sample points to be rendered in |
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* this audio fragment cycle by the audio engine |
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*/ |
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void Process(uint Samples) { |
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ModulationSystem::Event* pCtrlEvent = pEvents->first(); |
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int iSample = TriggerDelay; |
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while (iSample < Samples) { |
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int process_break = Samples; |
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if (pCtrlEvent && pCtrlEvent->FragmentPos() <= process_break) process_break = pCtrlEvent->FragmentPos(); |
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|
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if (Coeff > 0.0f) { // level going up |
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while (iSample < process_break && Level <= CurrentMax) { |
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Manipulator.ApplyLevel(Level, iSample); |
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iSample++; |
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Level += Coeff; |
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} |
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if (Level > CurrentMax) { |
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Coeff = -Coeff; // invert direction |
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Level += 2.0f * Coeff; |
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} |
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} |
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else if (Coeff < 0.0f) { // level going down |
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while (iSample < process_break && Level >= CurrentMin) { |
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Manipulator.ApplyLevel(Level, iSample); |
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iSample++; |
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Level += Coeff; |
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} |
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if (Level < CurrentMin) { |
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Coeff = -Coeff; // invert direction |
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Level += 2.0f * Coeff; |
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} |
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} |
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else { // no modulation at all (Coeff = 0.0) |
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switch (Propagation) { |
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case propagation_top_down: |
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Level = Max; |
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break; |
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case propagation_middle_balanced: |
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Level = Min + 0.5f * Range; |
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break; |
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case propagation_bottom_up: |
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Level = Min; |
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break; |
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} |
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while (iSample < process_break) { |
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Manipulator.ApplyLevel(Level, iSample); |
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iSample++; |
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} |
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} |
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|
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if (pCtrlEvent) { |
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RecalculateCoeff(pCtrlEvent->Value); |
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pCtrlEvent = pEvents->next(); |
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} |
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} |
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TriggerDelay = 0; |
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pEvents->clear(); |
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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 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 ExtControlValue - current MIDI value of the external |
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* controller for the time when the voice |
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* was triggered |
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* @param FlipPhase - inverts the oscillator wave |
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* @param Delay - number of sample points triggering should |
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* be delayed |
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*/ |
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void Trigger(float Frequency, uint16_t InternalDepth, uint16_t ExtControlDepth, uint16_t ExtControlValue, bool FlipPhase, uint Delay) { |
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this->Coeff = 0.0f; |
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this->InternalDepth = (InternalDepth / 1200.0f) * Range; |
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this->ExtControlDepthCoeff = (((float) ExtControlDepth / 1200.0f) / 127.0f) * Range; |
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this->TriggerDelay = Delay; |
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this->FrequencyCoeff = (2.0f * Frequency) / (float) ModulationSystem::SampleRate(); |
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|
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if (ExtController) RecalculateCoeff(ExtControlValue); |
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else RecalculateCoeff(0); |
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|
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switch (Propagation) { |
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case propagation_top_down: { |
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if (FlipPhase) { |
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Level = CurrentMin; |
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} |
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else { // normal case |
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Level = Max; |
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Coeff = -Coeff; // level starts at max. thus has to go down now |
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} |
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break; |
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} |
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case propagation_middle_balanced: { |
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Level = Min + 0.5f * Range; |
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if (FlipPhase) Coeff = -Coeff; // invert direction (going down) |
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break; |
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} |
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case propagation_bottom_up: { |
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if (FlipPhase) { |
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Level = CurrentMax; |
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Coeff = -Coeff; // level starts at max. thus has to go down now |
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} |
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else { // normal case |
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Level = Min; |
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} |
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break; |
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} |
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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 to inform the LFO about a change of |
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* the external controller's value. |
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* |
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* @param pEvent - control change event of external controller |
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*/ |
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inline void SendEvent(ModulationSystem::Event* pEvent) { |
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if (ExtController && pEvent->FragmentPos() >= this->TriggerDelay) pEvents->alloc_assign(*pEvent); |
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} |
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|
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/** |
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* Should always be called when the voice was killed. |
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*/ |
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void Reset() { |
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pEvents->clear(); |
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} |
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|
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protected: |
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RTEList<ModulationSystem::Event>* pEvents; |
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propagation_t Propagation; |
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int TriggerDelay; |
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float Min; |
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float Max; |
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float CurrentMin; |
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float CurrentMax; |
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float FrequencyCoeff; |
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float ExtControlDepthCoeff; |
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float InternalDepth; |
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float Range; |
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float Coeff; |
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float Level; |
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|
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inline void RecalculateCoeff(uint16_t ExtControlValue) { |
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float currentrange = InternalDepth + ExtControlValue * ExtControlDepthCoeff; |
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if (currentrange > Range) currentrange = Range; |
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Coeff = (Coeff < 0) ? -(currentrange * FrequencyCoeff) |
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: currentrange * FrequencyCoeff; |
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switch (Propagation) { |
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case propagation_top_down: { |
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CurrentMax = Max; |
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CurrentMin = Max - currentrange; |
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break; |
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} |
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case propagation_middle_balanced: { |
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float rangediff = (Range - currentrange) * 0.5f; |
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CurrentMax = Max - rangediff; |
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CurrentMin = Min + rangediff; |
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break; |
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} |
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case propagation_bottom_up: { |
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CurrentMax = Max - currentrange; |
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CurrentMin = Min; |
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break; |
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} |
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} |
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} |
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}; |
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|
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/** Amplification Manipulator |
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* |
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* Specialized manipulator for writing volume parameters to the synthesis |
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* parameter matrix. |
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*/ |
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class VCAManipulator { |
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public: |
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inline void ApplyLevel(float& Level, int& iSample) { |
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ModulationSystem::pDestinationParameter[ModulationSystem::destination_vca][iSample] *= Level; |
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} |
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}; |
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|
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/** Filter Cutoff Frequency Manipulator |
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* |
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* Specialized manipulator for writing filter cutoff frequency parameters to |
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* the synthesis parameter matrix. |
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*/ |
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class VCFCManipulator { |
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public: |
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inline void ApplyLevel(float& Level, int& iSample) { |
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ModulationSystem::pDestinationParameter[ModulationSystem::destination_vcfc][iSample] *= Level; |
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} |
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}; |
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|
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/** Pitch Manipulator |
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* |
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* Specialized manipulator for writing pitch parameters to the synthesis |
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* parameter matrix. |
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*/ |
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class VCOManipulator { |
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public: |
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inline void ApplyLevel(float& Level, int& iSample) { |
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ModulationSystem::pDestinationParameter[ModulationSystem::destination_vco][iSample] *= RTMath::CentsToFreqRatio(Level); |
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} |
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}; |
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|
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#endif // __LFO_H__ |