Simulation of the Gravity Beats app
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//
// Scales.h
// GravityBeats
//
// Created by Joshua Moerman on 1/25/13.
// Copyright (c) 2013 Vadovas. All rights reserved.
//
#ifndef GravityBeats_Scales_h
#define GravityBeats_Scales_h
#include <vector>
#include <cmath>
#include <iostream>
#include <fstream>
#include <stdexcept>
#include <cassert>
// http://www.phys.unsw.edu.au/jw/notes.html
inline float pitch_for_midi_note(int note){
// we say 440hz is 1 in our units
float exponent = (note - 69) / 12.0f;
return std::pow(2.0f, exponent);
}
struct Scale {
std::vector<int> notes;
int note_for_length(float length){
assert(notes.size() > 1);
// determine note
length /= 200.0;
float note = -std::log(length) / std::log(2.0f) * 12.0f + 69.0f;
// determine note in scale
auto it = notes.begin();
while(*it < note){
++it;
if(it == notes.end()) {
--it;
break;
}
}
// determine closest note in scale
if(it == notes.begin()){
return *it;
} else {
auto it2 = it - 1;
if(std::abs(*it - note) > std::abs(*it2 - note)){
return *it2;
} else {
return *it;
}
}
}
static Scale load_from_file(std::string filename){
std::ifstream file(filename);
if(!file) throw std::runtime_error("Couldn't open file " + filename);
Scale scale;
int note = 0;
while (file >> note) {
scale.notes.push_back(note);
}
std::sort(scale.notes.begin(), scale.notes.end());
return scale;
}
};
#endif