engines/common/LFOTriangleDiHarmonic.h

/***************************************************************************
 *                                                                         *
 *   Copyright (C) 2005, 2008 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 update(const uint16_t& ExtControlValue) {
                const float max = this->InternalDepth + ExtControlValue * this->ExtControlDepthCoeff;
                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) {
                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;

                c1 = 2.0f * M_PI * Frequency / (float) SampleRate;
                c2 = 2.0f * M_PI * Frequency / (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) {
                c1 = 2.0f * M_PI * Frequency / (float) SampleRate;
                c2 = 2.0f * M_PI * Frequency / (float) SampleRate * 3.0f;
            }

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

} // namespace LinuxSampler

#endif // __LS_LFOTRIANGLEDIHARMONIC_H__
1	schoenebeck	717	/***************************************************************************
2			* *
3	schoenebeck	1681	* Copyright (C) 2005, 2008 Christian Schoenebeck *
4	schoenebeck	717	* *
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	schoenebeck	1681	#define AMP2 -0.11425509f
28	schoenebeck	717
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	schoenebeck	721	return (real1 + real2 * AMP2) * normalizer + offset;
61	schoenebeck	717	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 update(const uint16_t& ExtControlValue) {
71	senkov	719	const float max = this->InternalDepth + ExtControlValue * this->ExtControlDepthCoeff;
72	schoenebeck	721	if (RANGE == range_unsigned) {
73	schoenebeck	1681	const float harmonicCompensation = 1.0f + fabsf(AMP2); // to compensate the compensation ;) (see trigger())
74	schoenebeck	717	normalizer = max * 0.5f;
75	schoenebeck	721	offset = normalizer * harmonicCompensation;
76			} else { // signed range
77	schoenebeck	717	normalizer = max;
78	schoenebeck	721	}
79	schoenebeck	717	}
80
81			/**
82			* Will be called by the voice when the key / voice was triggered.
83			*
84			* @param Frequency - frequency of the oscillator in Hz
85			* @param StartLevel - on which level the wave should start
86			* @param InternalDepth - firm, internal oscillator amplitude
87			* @param ExtControlDepth - defines how strong the external MIDI
88			* controller has influence on the
89			* oscillator amplitude
90	schoenebeck	721	* @param FlipPhase - inverts the oscillator wave against
91			* a horizontal axis
92	schoenebeck	717	* @param SampleRate - current sample rate of the engines
93			* audio output signal
94			*/
95			void trigger(float Frequency, start_level_t StartLevel, uint16_t InternalDepth, uint16_t ExtControlDepth, bool FlipPhase, unsigned int SampleRate) {
96	schoenebeck	1681	const float harmonicCompensation = 1.0f + fabsf(AMP2); // to compensate the 2nd harmonic's amplitude overhead
97			this->InternalDepth = (InternalDepth / 1200.0f) * this->Max / harmonicCompensation;
98	schoenebeck	721	this->ExtControlDepthCoeff = (((float) ExtControlDepth / 1200.0f) / 127.0f) * this->Max / harmonicCompensation;
99	schoenebeck	717
100			c1 = 2.0f * M_PI * Frequency / (float) SampleRate;
101			c2 = 2.0f * M_PI * Frequency / (float) SampleRate * 3.0f;
102
103	schoenebeck	721	double phi; // phase displacement
104	schoenebeck	717	switch (StartLevel) {
105	schoenebeck	721	case start_level_mid:
106			//FIXME: direct jumping to 90� and 270� doesn't work out due to numeric accuracy problems (causes wave deformation)
107			//phi = (FlipPhase) ? 0.5 * M_PI : 1.5 * M_PI; // 90� or 270�
108			//break;
109	schoenebeck	717	case start_level_max:
110	schoenebeck	721	phi = (FlipPhase) ? M_PI : 0.0; // 180� or 0�
111	schoenebeck	717	break;
112			case start_level_min:
113	schoenebeck	721	phi = (FlipPhase) ? 0.0 : M_PI; // 0� or 180�
114	schoenebeck	717	break;
115			}
116			real1 = real2 = cos(phi);
117			imag1 = imag2 = sin(phi);
118			}
119	iliev	2225
120			/**
121			* Should be invoked after the LFO is triggered with StartLevel
122			* start_level_min.
123			* @param phase From 0 to 360 degrees.
124			*/
125			void setPhase(float phase) {
126			if (phase < 0) phase = 0;
127			if (phase > 360) phase = 360;
128			phase /= 360.0f;
129
130			// FIXME: too heavy?
131			float steps = 1.0f / (c1 / (2.0f * M_PI)); // number of steps for one cycle
132			steps *= phase + 0.25f;
133			for (int i = 0; i < steps; i++) render();
134			}
135	iliev	2227
136			void setFrequency(float Frequency, unsigned int SampleRate) {
137			c1 = 2.0f * M_PI * Frequency / (float) SampleRate;
138			c2 = 2.0f * M_PI * Frequency / (float) SampleRate * 3.0f;
139			}
140	schoenebeck	717
141			private:
142			float c1;
143			float c2;
144			float real1;
145			float imag1;
146			float real2;
147			float imag2;
148			float normalizer;
149	schoenebeck	721	float offset;
150	schoenebeck	717	};
151
152			} // namespace LinuxSampler
153
154			#endif // __LS_LFOTRIANGLEDIHARMONIC_H__