Add fibonacci music box example

examples/fibonacci_music_box.cpp

@@ -0,0 +1,167 @@
+#include <psemek/audio/engine.hpp>
+#include <psemek/audio/wave/silence.hpp>
+#include <psemek/audio/wave/sine.hpp>
+#include <psemek/audio/wave/sawtooth.hpp>
+#include <psemek/audio/wave/square.hpp>
+#include <psemek/audio/wave/triangle.hpp>
+#include <psemek/audio/wave/karplus_strong.hpp>
+#include <psemek/audio/effect/volume.hpp>
+#include <psemek/audio/effect/fade_in.hpp>
+#include <psemek/audio/effect/fade_out.hpp>
+#include <psemek/audio/effect/compressor.hpp>
+#include <psemek/audio/effect/pause.hpp>
+#include <psemek/audio/effect/truncate.hpp>
+#include <psemek/audio/combine/concat.hpp>
+#include <psemek/audio/combine/loop.hpp>
+#include <psemek/audio/effect/pitch.hpp>
+#include <psemek/audio/effect/distortion.hpp>
+#include <psemek/audio/combine/duplicate.hpp>
+#include <psemek/audio/combine/stereo.hpp>
+#include <psemek/audio/combine/mixer.hpp>
+#include <psemek/audio/midi.hpp>
+#include <psemek/app/application_base.hpp>
+#include <psemek/app/default_application_factory.hpp>
+#include <psemek/log/log.hpp>
+#include <psemek/util/array.hpp>
+
+#include <unordered_map>
+
+// Inspired by https://www.youtube.com/watch?v=_aIf4WUCNZU
+
+using namespace psemek;
+
+std::vector<std::vector<geom::point<int, 2>>> fibonacci_cycles(int n)
+{
+	util::array<int, 2> cycle({n, n}, -1);
+
+	std::vector<std::vector<geom::point<int, 2>>> result;
+
+	for (int i = 0; i < n; ++i)
+	{
+		for (int j = 0; j < n; ++j)
+		{
+			if (cycle(i, j) != -1)
+				continue;
+
+			int cycle_id = result.size();
+			auto & current = result.emplace_back();
+
+			geom::point p{i, j};
+			while (true)
+			{
+				current.push_back(p);
+				cycle(p[0], p[1]) = cycle_id;
+				p = {p[1], (p[0] + p[1]) % n};
+
+				if (p == geom::point{i, j})
+					break;
+			}
+		}
+	}
+
+	return result;
+}
+
+std::vector<int> major_scale()
+{
+	return {0, 2, 4, 5, 7, 9, 11};
+}
+
+std::vector<int> minor_scale()
+{
+	return {0, 2, 3, 5, 7, 8, 10};
+}
+
+std::shared_ptr<audio::stream> note(int i, float duration)
+{
+	return audio::fade_in(audio::fade_out(audio::karplus_strong(audio::midi_frequency(69 + i)), duration), duration / 16.f);
+}
+
+std::shared_ptr<audio::track> generate(std::vector<int> const & scale, std::vector<geom::point<int, 2>> const & cycle, float speed)
+{
+	auto mixer = audio::make_mixer();
+
+	for (int i = 0; i < cycle.size(); ++i)
+		mixer->add(audio::concat({audio::truncate(audio::silence(), speed * i), note(scale[cycle[i][0] % scale.size()] + 12 * (cycle[i][0] / scale.size()), speed)}));
+
+	return audio::record(mixer, speed * cycle.size());
+}
+
+struct fibonacci_music_box_app
+	: app::application_base
+{
+	fibonacci_music_box_app(options const &, context const &)
+	{
+		auto cycles = fibonacci_cycles(16);
+
+		auto scale = minor_scale();
+		float speed = 0.25f;
+
+		log::info() << "Found cycles of length:";
+		for (int i = 0; i < cycles.size(); ++i)
+		{
+			log::info() << "    #" << i << ": " << cycles[i].size();
+			cycles_.push_back(audio::loop(generate(scale, cycles[i], speed)));
+		}
+
+		channels_.resize(cycles_.size());
+
+		engine_ = audio::make_engine();
+		mixer_ = audio::make_mixer();
+
+		auto compressor = audio::compressor(mixer_, audio::from_db(-2.f), 0.95f, 0.002f, 1.f, audio::from_db(1.f));
+		engine_->output()->stream(compressor);
+
+	}
+
+	void on_event(app::key_event const & event) override
+	{
+		app::application_base::on_event(event);
+
+		if (event.down && event.key >= app::keycode::NUM_1 && event.key <= app::keycode::NUM_0)
+		{
+			int i;
+			if (event.key == app::keycode::NUM_0)
+				i = 0;
+			else
+				i = 1 + (int(event.key) - int(app::keycode::NUM_1));
+
+			log::info() << "Pressed " << i;
+
+			if (i < channels_.size())
+			{
+				if (channels_[i])
+				{
+					channels_[i]->stop();
+					channels_[i] = nullptr;
+				}
+				else
+				{
+					channels_[i] = mixer_->add(cycles_[i]);
+				}
+			}
+		}
+	}
+
+	void update() override
+	{}
+
+	void present() override
+	{}
+
+private:
+	std::unique_ptr<audio::engine> engine_;
+	audio::mixer_ptr mixer_;
+	std::vector<audio::stream_ptr> cycles_;
+	std::vector<audio::channel_ptr> channels_;
+};
+
+namespace psemek::app
+{
+
+	std::unique_ptr<application::factory> make_application_factory()
+	{
+		return default_application_factory<fibonacci_music_box_app>({.name = "Fibonacci music box"});
+	}
+
+}