/[svn]/linuxsampler/trunk/src/engines/gig/EGDecay.h
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Annotation of /linuxsampler/trunk/src/engines/gig/EGDecay.h

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Revision 829 - (hide annotations) (download) (as text)
Sat Jan 14 14:07:47 2006 UTC (18 years, 2 months ago) by schoenebeck
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* implemented portamento mode and solo mode (a.k.a 'mono mode'):
  all modes can be altered via standard GM messages, that is CC5 for
  altering portamento time, CC65 for enabling / disabling portamento
  mode, CC126 for enabling solo mode and CC127 for disabling solo mode
* fixed EG3 (pitch envelope) synthesis which was neutral all the time
* configure.in: do not automatically pick optimized gcc flags if the user
  already provided some on his own (as CXXFLAGS)

1 schoenebeck 53 /***************************************************************************
2     * *
3     * LinuxSampler - modular, streaming capable sampler *
4     * *
5 schoenebeck 56 * Copyright (C) 2003, 2004 by Benno Senoner and Christian Schoenebeck *
6 schoenebeck 829 * Copyright (C) 2005, 2006 Christian Schoenebeck *
7 schoenebeck 53 * *
8 schoenebeck 738 * This library is free software; you can redistribute it and/or modify *
9 schoenebeck 53 * it under the terms of the GNU General Public License as published by *
10     * the Free Software Foundation; either version 2 of the License, or *
11     * (at your option) any later version. *
12     * *
13 schoenebeck 738 * This library is distributed in the hope that it will be useful, *
14 schoenebeck 53 * but WITHOUT ANY WARRANTY; without even the implied warranty of *
15     * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the *
16     * GNU General Public License for more details. *
17     * *
18     * You should have received a copy of the GNU General Public License *
19 schoenebeck 738 * along with this library; if not, write to the Free Software *
20 schoenebeck 53 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, *
21     * MA 02111-1307 USA *
22     ***************************************************************************/
23    
24     #ifndef __LS_GIG_EGDECAY_H__
25     #define __LS_GIG_EGDECAY_H__
26    
27     #include "../../common/global.h"
28     #include "../../common/RTMath.h"
29    
30     namespace LinuxSampler { namespace gig {
31    
32 schoenebeck 738 /** @brief Decay Envelope Generator (linear)
33 schoenebeck 53 *
34 schoenebeck 738 * Simple Envelope Generator with only one stage: 'Decay' which is a
35     * linear segment. The initial envelope level (given by 'Depth') will
36     * raise / drop in 'DecayTime' seconds to a level of exactly 1.0. If
37     * the initial level ('Depth') is already 1.0, nothing happens.
38 schoenebeck 53 */
39     class EGDecay {
40     public:
41 schoenebeck 738 EGDecay();
42    
43     /**
44     * Will be called by the voice when the key / voice was
45     * triggered and initialize the envelope generator.
46     *
47     * @param Depth - initial level of the envelope
48     * @param DecayTime - decay time of the envelope (0.000 - 10.000s)
49     * @param SampleRate - sample rate of used audio driver
50     */
51     void trigger(float Depth, float DecayTime, unsigned int SampleRate); //FIXME: we should better use 'float' for SampleRate
52    
53     /**
54     * Returns true if envelope is still in stage 'Decay', returns
55     * false if end of envelope is reached.
56     */
57     inline bool active() {
58     return (bool) Coeff;
59     }
60    
61     /**
62     * Advance envelope by \a SamplePoints steps.
63     */
64     inline void increment(const int SamplePoints) {
65     StepsLeft = RTMath::Max(0, StepsLeft - SamplePoints);
66     }
67    
68     /**
69     * Returns amount of steps until end of envelope is reached.
70     */
71     inline int toEndLeft() {
72     return StepsLeft;
73     }
74    
75     /**
76     * Should be called once the end of the envelope is reached. It
77     * will neutralize the envelope coefficient to not alter the
78     * envelope anymore and will set the output level to final level
79     * of exactly 1.0f. So after this call, render() can still
80     * safely be called from the sampler's main synthesis loop.
81     */
82     inline void update() {
83     Level = 1.0f;
84     Coeff = 0.0f;
85     }
86    
87     /**
88     * Calculates exactly one level of the envelope.
89     *
90     * @returns next envelope level
91     */
92     inline float render() {
93     return (Level += Coeff);
94     }
95    
96 schoenebeck 829 /**
97     * Returns the level which this envelope will have in
98     * \a SamplePoints steps. It will not alter anything.
99     */
100     inline float level(const int SamplePoints) const {
101     return Level + RTMath::Min(SamplePoints, StepsLeft) * Coeff;
102     }
103    
104 schoenebeck 738 private:
105     float Level; ///< current EG output level
106     float Coeff; ///< linear coefficient for changing the output level in time
107     int StepsLeft; ///< how many steps left until end is reached
108 schoenebeck 53 };
109    
110     }} // namespace LinuxSampler::gig
111    
112     #endif // __LS_GIG_EGDECAY_H__

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