copied source from Gravity Beats

Beat.h

@@ -0,0 +1,86 @@
+//
+//  Beat.h
+//  GravityBeats
+//
+//  Created by Joshua Moerman on 1/9/13.
+//  Copyright (c) 2013 Vadovas. All rights reserved.
+//
+
+#ifndef GravityBeats_Beat_h
+#define GravityBeats_Beat_h
+
+#include <vector>
+#include <cmath>
+
+#include "UserInformation.h"
+
+template <typename Information>
+struct Note : public UserInformation<Information>{
+	// see http://en.wikipedia.org/wiki/Note_value
+	enum Speed {
+		kWholeNote	=1,	// 1 in one measure
+		kHalfNote	=2,	// 2 in one measure
+		kTriplet	=3,	// 3 in one measure
+		kQuarterNote	=4,	// 4
+		kHalfTriplet	=6,	// 6
+		kEighthNote	=8	// 8
+	} speed;
+	int progress = -2;
+
+	template <typename... S>
+	Note(Speed speed, S... args)
+	: UserInformation<Information>(args...)
+	, speed(speed)
+	{}
+
+	// we could return how much it is off, to give the balls the right initial position and speed.
+	bool update(float time_in_measure){
+		int new_progress = std::floor(time_in_measure*speed);
+		if(new_progress != progress){
+			if(progress == -2){
+				progress = new_progress;
+				return false;
+			} else {
+				progress = new_progress;
+				return true;
+			}
+		}
+		return false;
+	}
+
+	void reset(){
+		progress = -1;
+	}
+};
+
+template <typename NoteInformation>
+struct Beat {
+	float total_length{4.0};		// 60 bpm
+	float time{-0.1};
+
+	std::vector<Note<NoteInformation>> notes;
+
+	std::vector<NoteInformation> update(float dt){
+		std::vector<NoteInformation> ret;
+		time += dt;
+
+		// not needed, but keeps the floats small
+		// also usefull when we want to change bpm
+		if(time > total_length){
+			time -= total_length;
+			for(auto& n : notes){
+				n.reset();
+			}
+		}
+
+		for(auto& n : notes){
+			if(n.update(time / total_length)){
+				ret.push_back(n.information);
+			}
+		}
+
+		return ret;
+	}
+};
+
+#endif

Math.h

@@ -0,0 +1,99 @@
+//
+//  Math.h
+//  GravityBeats
+//
+//  Created by Joshua Moerman on 1/12/13.
+//  Copyright (c) 2013 Vadovas. All rights reserved.
+//
+
+#ifndef GravityBeats_Math_h
+#define GravityBeats_Math_h
+
+#include <cmath>
+
+namespace math {
+	struct Vec2 {
+		float x, y;
+
+		Vec2& operator *= (float rh){
+			x *= rh;
+			y *= rh;
+			return *this;
+		}
+
+		Vec2& operator+= (Vec2 const & rh){
+			x += rh.x;
+			y += rh.y;
+			return *this;
+		}
+
+		float sqr_length() const {
+			return x*x + y*y;
+		}
+
+		float length() const {
+			return std::sqrt(sqr_length());
+		}
+
+		Vec2& normalize(){
+			const float l = length();
+			if(l == 0.0f) { return *this; }
+			x /= l;
+			y /= l;
+			return *this;
+		}
+	};
+
+	inline Vec2 operator*(float lh, Vec2 rh){
+		rh *= lh;
+		return rh;
+	}
+
+	inline Vec2 operator+(Vec2 lh, Vec2 const & rh){
+		return lh += rh;
+	}
+
+	inline Vec2 operator-(Vec2 lh, Vec2 const & rh){
+		return lh += -1.0*rh;
+	}
+
+	inline float dot(Vec2 const & lh, Vec2 const & rh){
+		return lh.x*rh.x + lh.y*rh.y;
+	}
+
+	inline Vec2 rotate_ccw(Vec2 v){
+		std::swap(v.x, v.y);
+		v.x *= -1.0;
+		return v;
+	}
+
+	inline Vec2 normalize(Vec2 v){
+		return v.normalize();
+	}
+
+	inline float distance_point_point(Vec2 p1, Vec2 p2){
+		return (p2 - p1).length();
+	}
+
+	// p point, [v,w] line segment
+	inline float distance_point_line(Vec2 p, Vec2 v, Vec2 w){
+		// http://stackoverflow.com/questions/849211/shortest-distance-between-a-point-and-a-line-segment
+		const float l2 = (v-w).sqr_length();
+		if (l2 == 0.0) return distance_point_point(p, v);
+
+		const float t = dot(p - v, w - v) / l2;
+		if (t < 0.0) return distance_point_point(p, v);
+		else if (t > 1.0) return distance_point_point(p, w);
+
+		auto projection = v + t * (w - v);
+		return distance_point_point(p, projection);
+	}
+
+	template <typename T>
+	constexpr T clamp(T input, T min, T max){
+		return input > max ? max :
+		input < min ? min : input;
+	}
+}
+
+#endif

Scales.h

@@ -0,0 +1,70 @@
+//
+//  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>
+
+// 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){
+		// 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 != notes.end()){
+			++it;
+		}
+
+		// 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