engines/common/LFOTriangleDiHarmonic.h

/***************************************************************************
 *                                                                         *
 *   Copyright (C) 2005 - 2017 Christian Schoenebeck                       *
 *                                                                         *
 *   This library is free software; you can redistribute it and/or modify  *
 *   it under the terms of the GNU General Public License as published by  *
 *   the Free Software Foundation; either version 2 of the License, or     *
 *   (at your option) any later version.                                   *
 *                                                                         *
 *   This library is distributed in the hope that it will be useful,       *
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of        *
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the         *
 *   GNU General Public License for more details.                          *
 *                                                                         *
 *   You should have received a copy of the GNU General Public License     *
 *   along with this library; if not, write to the Free Software           *
 *   Foundation, Inc., 59 Temple Place, Suite 330, Boston,                 *
 *   MA  02111-1307  USA                                                   *
 ***************************************************************************/

#ifndef __LS_LFOTRIANGLEDIHARMONIC_H__
#define __LS_LFOTRIANGLEDIHARMONIC_H__

#include "LFOBase.h"

// amplitue of 2nd harmonic (to approximate the triangular wave)
#define AMP2    -0.11425509f

namespace LinuxSampler {

    /** @brief Triangle LFO (di-harmonic implementation)
     *
     * This is a triangle Low Frequency Oscillator implementation which uses
     * a di-harmonic solution. This means it sums up two harmonics
     * (sinusoids) to approximate a triangular wave.
     */
    template<range_type_t RANGE>
    class LFOTriangleDiHarmonic : public LFOBase<RANGE> {
        public:

            /**
             * Constructor
             *
             * @param Max - maximum value of the output levels
             */
            LFOTriangleDiHarmonic(float Max) : LFOBase<RANGE>::LFOBase(Max) {
            }

            /**
             * Calculates exactly one sample point of the LFO wave.
             *
             * @returns next LFO level
             */
            inline float render() {
                real1 -= c1 * imag1;
                imag1 += c1 * real1;
                real2 -= c2 * imag2;
                imag2 += c2 * real2;
                if (RANGE == range_unsigned)
                    return (real1 + real2 * AMP2) * normalizer + offset;
                else /* signed range */
                    return (real1 + real2 * AMP2) * normalizer;
            }

            /**
             * Update LFO depth with a new external controller value.
             *
             * @param ExtControlValue - new external controller value
             */
            inline void updateByMIDICtrlValue(const uint16_t& ExtControlValue) {
                this->ExtControlValue = ExtControlValue;

                const float max = (this->InternalDepth + ExtControlValue * this->ExtControlDepthCoeff) * this->ScriptDepthFactor;
                if (RANGE == range_unsigned) {
                    const float harmonicCompensation = 1.0f + fabsf(AMP2); // to compensate the compensation ;) (see trigger())
                    normalizer = max * 0.5f;
                    offset     = normalizer * harmonicCompensation;
                } else { // signed range
                    normalizer = max;
                }
            }

            /**
             * Will be called by the voice when the key / voice was triggered.
             *
             * @param Frequency       - frequency of the oscillator in Hz
             * @param StartLevel      - on which level the wave should start
             * @param InternalDepth   - firm, internal oscillator amplitude
             * @param ExtControlDepth - defines how strong the external MIDI
             *                          controller has influence on the
             *                          oscillator amplitude
             * @param FlipPhase       - inverts the oscillator wave against
             *                          a horizontal axis
             * @param SampleRate      - current sample rate of the engines
             *                          audio output signal
             */
            void trigger(float Frequency, start_level_t StartLevel, uint16_t InternalDepth, uint16_t ExtControlDepth, bool FlipPhase, unsigned int SampleRate) {
                this->Frequency = Frequency;
                this->ScriptFrequencyFactor = this->ScriptDepthFactor = 1.f; // reset for new voice
                const float harmonicCompensation = 1.0f + fabsf(AMP2); // to compensate the 2nd harmonic's amplitude overhead
                this->InternalDepth        = (InternalDepth / 1200.0f) * this->Max / harmonicCompensation;
                this->ExtControlDepthCoeff = (((float) ExtControlDepth / 1200.0f) / 127.0f) * this->Max / harmonicCompensation;

                const float freq = Frequency * this->ScriptFrequencyFactor;
                c1 = 2.0f * M_PI * freq / (float) SampleRate;
                c2 = 2.0f * M_PI * freq / (float) SampleRate * 3.0f;

                double phi; // phase displacement
                switch (StartLevel) {
                    case start_level_mid:
                        //FIXME: direct jumping to 90� and 270� doesn't work out due to numeric accuracy problems (causes wave deformation)
                        //phi = (FlipPhase) ? 0.5 * M_PI : 1.5 * M_PI; // 90� or 270�
                        //break;
                    case start_level_max:
                        phi = (FlipPhase) ? M_PI : 0.0; // 180� or 0�
                        break;
                    case start_level_min:
                        phi = (FlipPhase) ? 0.0 : M_PI; // 0� or 180�
                        break;
                }
                real1 = real2 = cos(phi);
                imag1 = imag2 = sin(phi);
            }
            
            /**
             * Should be invoked after the LFO is triggered with StartLevel
             * start_level_min.
             * @param phase From 0 to 360 degrees.
             */
            void setPhase(float phase) {
                if (phase < 0) phase = 0;
                if (phase > 360) phase = 360;
                phase /= 360.0f;
                
                // FIXME: too heavy?
                float steps = 1.0f / (c1 / (2.0f * M_PI)); // number of steps for one cycle
                steps *= phase + 0.25f;
                for (int i = 0; i < steps; i++) render();
            }
            
            void setFrequency(float Frequency, unsigned int SampleRate) {
                this->Frequency = Frequency;
                const float freq = Frequency * this->ScriptFrequencyFactor;
                c1 = 2.0f * M_PI * freq / (float) SampleRate;
                c2 = 2.0f * M_PI * freq / (float) SampleRate * 3.0f;
            }

            void setScriptDepthFactor(float factor) {
                this->ScriptDepthFactor = factor;
                updateByMIDICtrlValue(this->ExtControlValue);
            }

            void setScriptFrequencyFactor(float factor, unsigned int SampleRate) {
                this->ScriptFrequencyFactor = factor;
                setFrequency(this->Frequency, SampleRate);
            }

        private:
            float c1;
            float c2;
            float real1;
            float imag1;
            float real2;
            float imag2;
            float normalizer;
            float offset;
    };

} // namespace LinuxSampler

#endif // __LS_LFOTRIANGLEDIHARMONIC_H__
1	/***************************************************************************
2	* *
3	* Copyright (C) 2005 - 2017 Christian Schoenebeck *
4	* *
5	* This library is free software; you can redistribute it and/or modify *
6	* it under the terms of the GNU General Public License as published by *
7	* the Free Software Foundation; either version 2 of the License, or *
8	* (at your option) any later version. *
9	* *
10	* This library is distributed in the hope that it will be useful, *
11	* but WITHOUT ANY WARRANTY; without even the implied warranty of *
12	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the *
13	* GNU General Public License for more details. *
14	* *
15	* You should have received a copy of the GNU General Public License *
16	* along with this library; if not, write to the Free Software *
17	* Foundation, Inc., 59 Temple Place, Suite 330, Boston, *
18	* MA 02111-1307 USA *
19	***************************************************************************/
20
21	#ifndef __LS_LFOTRIANGLEDIHARMONIC_H__
22	#define __LS_LFOTRIANGLEDIHARMONIC_H__
23
24	#include "LFOBase.h"
25
26	// amplitue of 2nd harmonic (to approximate the triangular wave)
27	#define AMP2 -0.11425509f
28
29	namespace LinuxSampler {
30
31	/** @brief Triangle LFO (di-harmonic implementation)
32	*
33	* This is a triangle Low Frequency Oscillator implementation which uses
34	* a di-harmonic solution. This means it sums up two harmonics
35	* (sinusoids) to approximate a triangular wave.
36	*/
37	template<range_type_t RANGE>
38	class LFOTriangleDiHarmonic : public LFOBase<RANGE> {
39	public:
40
41	/**
42	* Constructor
43	*
44	* @param Max - maximum value of the output levels
45	*/
46	LFOTriangleDiHarmonic(float Max) : LFOBase<RANGE>::LFOBase(Max) {
47	}
48
49	/**
50	* Calculates exactly one sample point of the LFO wave.
51	*
52	* @returns next LFO level
53	*/
54	inline float render() {
55	real1 -= c1 * imag1;
56	imag1 += c1 * real1;
57	real2 -= c2 * imag2;
58	imag2 += c2 * real2;
59	if (RANGE == range_unsigned)
60	return (real1 + real2 * AMP2) * normalizer + offset;
61	else /* signed range */
62	return (real1 + real2 * AMP2) * normalizer;
63	}
64
65	/**
66	* Update LFO depth with a new external controller value.
67	*
68	* @param ExtControlValue - new external controller value
69	*/
70	inline void updateByMIDICtrlValue(const uint16_t& ExtControlValue) {
71	this->ExtControlValue = ExtControlValue;
72
73	const float max = (this->InternalDepth + ExtControlValue * this->ExtControlDepthCoeff) * this->ScriptDepthFactor;
74	if (RANGE == range_unsigned) {
75	const float harmonicCompensation = 1.0f + fabsf(AMP2); // to compensate the compensation ;) (see trigger())
76	normalizer = max * 0.5f;
77	offset = normalizer * harmonicCompensation;
78	} else { // signed range
79	normalizer = max;
80	}
81	}
82
83	/**
84	* Will be called by the voice when the key / voice was triggered.
85	*
86	* @param Frequency - frequency of the oscillator in Hz
87	* @param StartLevel - on which level the wave should start
88	* @param InternalDepth - firm, internal oscillator amplitude
89	* @param ExtControlDepth - defines how strong the external MIDI
90	* controller has influence on the
91	* oscillator amplitude
92	* @param FlipPhase - inverts the oscillator wave against
93	* a horizontal axis
94	* @param SampleRate - current sample rate of the engines
95	* audio output signal
96	*/
97	void trigger(float Frequency, start_level_t StartLevel, uint16_t InternalDepth, uint16_t ExtControlDepth, bool FlipPhase, unsigned int SampleRate) {
98	this->Frequency = Frequency;
99	this->ScriptFrequencyFactor = this->ScriptDepthFactor = 1.f; // reset for new voice
100	const float harmonicCompensation = 1.0f + fabsf(AMP2); // to compensate the 2nd harmonic's amplitude overhead
101	this->InternalDepth = (InternalDepth / 1200.0f) * this->Max / harmonicCompensation;
102	this->ExtControlDepthCoeff = (((float) ExtControlDepth / 1200.0f) / 127.0f) * this->Max / harmonicCompensation;
103
104	const float freq = Frequency * this->ScriptFrequencyFactor;
105	c1 = 2.0f * M_PI * freq / (float) SampleRate;
106	c2 = 2.0f * M_PI * freq / (float) SampleRate * 3.0f;
107
108	double phi; // phase displacement
109	switch (StartLevel) {
110	case start_level_mid:
111	//FIXME: direct jumping to 90� and 270� doesn't work out due to numeric accuracy problems (causes wave deformation)
112	//phi = (FlipPhase) ? 0.5 * M_PI : 1.5 * M_PI; // 90� or 270�
113	//break;
114	case start_level_max:
115	phi = (FlipPhase) ? M_PI : 0.0; // 180� or 0�
116	break;
117	case start_level_min:
118	phi = (FlipPhase) ? 0.0 : M_PI; // 0� or 180�
119	break;
120	}
121	real1 = real2 = cos(phi);
122	imag1 = imag2 = sin(phi);
123	}
124
125	/**
126	* Should be invoked after the LFO is triggered with StartLevel
127	* start_level_min.
128	* @param phase From 0 to 360 degrees.
129	*/
130	void setPhase(float phase) {
131	if (phase < 0) phase = 0;
132	if (phase > 360) phase = 360;
133	phase /= 360.0f;
134
135	// FIXME: too heavy?
136	float steps = 1.0f / (c1 / (2.0f * M_PI)); // number of steps for one cycle
137	steps *= phase + 0.25f;
138	for (int i = 0; i < steps; i++) render();
139	}
140
141	void setFrequency(float Frequency, unsigned int SampleRate) {
142	this->Frequency = Frequency;
143	const float freq = Frequency * this->ScriptFrequencyFactor;
144	c1 = 2.0f * M_PI * freq / (float) SampleRate;
145	c2 = 2.0f * M_PI * freq / (float) SampleRate * 3.0f;
146	}
147
148	void setScriptDepthFactor(float factor) {
149	this->ScriptDepthFactor = factor;
150	updateByMIDICtrlValue(this->ExtControlValue);
151	}
152
153	void setScriptFrequencyFactor(float factor, unsigned int SampleRate) {
154	this->ScriptFrequencyFactor = factor;
155	setFrequency(this->Frequency, SampleRate);
156	}
157
158	private:
159	float c1;
160	float c2;
161	float real1;
162	float imag1;
163	float real2;
164	float imag2;
165	float normalizer;
166	float offset;
167	};
168
169	} // namespace LinuxSampler
170
171	#endif // __LS_LFOTRIANGLEDIHARMONIC_H__