You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
91 lines
3.0 KiB
91 lines
3.0 KiB
/*
|
|
* Copyright 2010 Google Inc.
|
|
*
|
|
* Licensed under the Apache License, Version 2.0 (the "License");
|
|
* you may not use this file except in compliance with the License.
|
|
* You may obtain a copy of the License at
|
|
*
|
|
* http://www.apache.org/licenses/LICENSE-2.0
|
|
*
|
|
* Unless required by applicable law or agreed to in writing, software
|
|
* distributed under the License is distributed on an "AS IS" BASIS,
|
|
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
|
|
* See the License for the specific language governing permissions and
|
|
* limitations under the License.
|
|
*/
|
|
|
|
package com.levien.synthesizer.core.model.modules;
|
|
|
|
import com.levien.synthesizer.core.model.CachedFrequencyProvider;
|
|
import com.levien.synthesizer.core.model.FrequencyProvider;
|
|
import com.levien.synthesizer.core.model.SignalProvider;
|
|
import com.levien.synthesizer.core.model.SynthesisTime;
|
|
|
|
/**
|
|
* Glide smooths changes in frequency over time.
|
|
*/
|
|
public class Glide extends CachedFrequencyProvider {
|
|
/**
|
|
* Creates a Glide module to wrap source.
|
|
* @param source - The input frequency to smooth.
|
|
* @param rate - The time in seconds in which output should change to a new input.
|
|
*/
|
|
public Glide(FrequencyProvider source, SignalProvider rate) {
|
|
source_ = source;
|
|
rate_ = rate;
|
|
previousLogFrequency_ = 0.0;
|
|
nextLogFrequency_ = 0.0;
|
|
}
|
|
|
|
public double computeLogFrequency(SynthesisTime time) {
|
|
double currentLogFrequency = source_.getLogFrequency(time);
|
|
double rate = rate_.getValue(time);
|
|
|
|
// If rate is 0 seconds, then don't do anything.
|
|
if (rate == 0.0) {
|
|
previousLogFrequency_ = currentLogFrequency;
|
|
nextLogFrequency_ = currentLogFrequency;
|
|
return currentLogFrequency;
|
|
}
|
|
|
|
// It hasn't changed, so don't do anything.
|
|
if (currentLogFrequency == previousLogFrequency_ &&
|
|
nextLogFrequency_ == previousLogFrequency_) {
|
|
return currentLogFrequency;
|
|
}
|
|
|
|
// See where we are, based on where we were last heading.
|
|
double timeSinceChange = time.getAbsoluteTime() - switchTime_;
|
|
double output;
|
|
if (timeSinceChange > rate) {
|
|
output = nextLogFrequency_;
|
|
} else {
|
|
output = previousLogFrequency_ +
|
|
(timeSinceChange / rate) * (nextLogFrequency_ - previousLogFrequency_);
|
|
}
|
|
|
|
// Adjust if there is a new destination.
|
|
if (currentLogFrequency != nextLogFrequency_) {
|
|
previousLogFrequency_ = output;
|
|
nextLogFrequency_ = currentLogFrequency;
|
|
switchTime_ = time.getAbsoluteTime();
|
|
}
|
|
|
|
return output;
|
|
}
|
|
|
|
// The wrapped frequency provider to take as input and output smoothed.
|
|
private FrequencyProvider source_;
|
|
|
|
// The time in seconds in which output should change to a new input.
|
|
private SignalProvider rate_;
|
|
|
|
// The log frequency that was being output last time the input switched.
|
|
private double previousLogFrequency_;
|
|
|
|
// The log frequency of the input that this module is moving toward.
|
|
private double nextLogFrequency_;
|
|
|
|
// The last time that in the input frequency changed.
|
|
private double switchTime_;
|
|
}
|
|
|