From 82607781cf7590d28f1d0f0ae750dbc62a7f89de Mon Sep 17 00:00:00 2001
From: lisyarus <lisyarus@gmail.com>
Date: Sun, 16 Oct 2022 00:22:18 +0300
Subject: [PATCH] Audio example tweaks

---
 examples/audio.cpp | 98 ++++++++++++++++++++++++++++++++++++++--------
 1 file changed, 82 insertions(+), 16 deletions(-)

diff --git a/examples/audio.cpp b/examples/audio.cpp
index 9703f06f..884b0895 100644
--- a/examples/audio.cpp
+++ b/examples/audio.cpp
@@ -67,6 +67,16 @@ static std::map<SDL_Keycode, int> const key_to_midi
 	{SDLK_RIGHTBRACKET, 91},
 };
 
+static geom::interval<int> const key_rows[3] = {
+	{59, 68},
+	{69, 79},
+	{80, 91},
+};
+
+static std::string_view const midi_name[12] = {
+	"A", "A#", "B", "C", "C#", "D", "D#", "E", "F", "F#", "G", "G#",
+};
+
 struct audio_app
 	: app::app
 {
@@ -86,12 +96,15 @@ struct audio_app
 	{
 		app::app::on_key_down(key);
 
-		if (key_to_midi.contains(key) && !channels_.contains(key))
+		if (key_to_midi.contains(key))
 		{
 			int midi = key_to_midi.at(key);
-			auto tone = audio::karplus_strong(440.f * std::pow(2.f, (midi - 69) / 12.f));
-			tone = audio::distortion(std::move(tone));
-			channels_[key] = mixer_->add(audio::fade_in(tone, 0.002f));
+			if (!channels_.contains(midi))
+			{
+				auto tone = audio::karplus_strong(440.f * std::pow(2.f, (midi - 69) / 12.f));
+				tone = audio::distortion(std::move(tone), 4.f);
+				channels_[midi] = mixer_->add(audio::fade_in(tone, 0.005f));
+			}
 		}
 
 		if (key == SDLK_SPACE)
@@ -110,12 +123,13 @@ struct audio_app
 	{
 		app::app::on_key_up(key);
 
-		if (channels_.contains(key))
+		if (key_to_midi.contains(key))
 		{
-			auto & ch = channels_[key];
+			int midi = key_to_midi.at(key);
+			auto & ch = channels_[midi];
 			if (auto s = ch->stream())
-				ch->stream(audio::fade_out(s, 0.01f));
-			channels_.erase(key);
+				ch->stream(audio::fade_out(s, 0.1f));
+			channels_.erase(midi);
 		}
 
 		if (key == SDLK_KP_PLUS)
@@ -127,9 +141,12 @@ struct audio_app
 
 	void update() override
 	{
-		float const time = clock_.count();
+		float const dt = clock_.restart().count();
+		time_ += dt;
 
-		float volume = std::sin(time);
+		smooth_pitch_ += (12.f * std::log2(pitch_control_->pitch()) - smooth_pitch_) * (1.f - std::exp(- 20.f * dt));
+
+		float volume = std::sin(time_);
 		volume_control_->gain_left(0.5f + 0.5f * volume);
 		volume_control_->gain_right(0.5f - 0.5f * volume);
 	}
@@ -139,12 +156,58 @@ struct audio_app
 		gl::ClearColor(0.8f, 0.8f, 1.f, 1.f);
 		gl::Clear(gl::COLOR_BUFFER_BIT);
 
+		float size = 64.f;
+		float margin = 4.f;
+		float border = 8.f;
+
+		float center = width() / 2.f;
+		float y = height() / 2.f + size * std::size(key_rows) / 2.f;
+
+		gfx::painter::text_options opts;
+		opts.scale = 2.f;
+		opts.c = {0, 0, 0, 255};
+		opts.x = gfx::painter::x_align::center;
+		opts.y = gfx::painter::y_align::center;
+
+		for (auto const & row : key_rows)
 		{
-			gfx::painter::text_options opts;
-			opts.x = gfx::painter::x_align::left;
-			opts.y = gfx::painter::y_align::top;
-			opts.scale = 2.f;
-			opts.c = {0, 0, 0, 255};
+			y -= size;
+
+			float x = center - (row.max - row.min + 1) * size / 2.f;
+
+			for (int i = 0; i <= row.max - row.min; ++i)
+			{
+				gfx::color_rgba color{0, 0, 0, 255};
+				if (channels_.contains(row.min + i))
+					color = {255, 127, 0, 255};
+				painter_.rect({{{x + margin, x + size - margin}, {y + margin, y + size - margin}}}, color);
+
+				color = {255, 255, 255, 255};
+				painter_.rect({{{x + border, x + size - border}, {y + border, y + size - border}}}, color);
+
+				painter_.text({x + size / 2.f, y + size / 2.f}, midi_name[(row.min + i + 3) % 12], opts);
+
+				x += size;
+			}
+		}
+
+		opts.scale = 4.f;
+		opts.c = pause_control_->paused() ? gfx::color_rgba{255, 0, 0, 255} : gfx::color_rgba{0, 127, 0, 255};
+		painter_.text({width() / 2.f, height() - 200.f}, pause_control_->paused() ? "PAUSED" : "PLAYING", opts);
+
+		{
+			float x = width() - 200.f;
+			float y = height() / 2.f;
+
+			float w = 4.f;
+			float h = 64.f;
+
+			float s = 16.f;
+			float r = y - h * smooth_pitch_;
+
+			painter_.rect({{{x - w, x + w}, {y - h, y + h}}}, {0, 0, 0, 255});
+
+			painter_.rect({{{x - s, x + s}, {r - w, r + w}}}, {0, 0, 255, 255});
 		}
 
 		painter_.render(geom::window_camera{width(), height()}.transform());
@@ -161,9 +224,12 @@ private:
 	std::shared_ptr<audio::volume_control_stereo> volume_control_;
 	std::shared_ptr<audio::pitch_control> pitch_control_;
 	std::shared_ptr<audio::pause_control> pause_control_;
-	std::map<SDL_Keycode, audio::channel_ptr> channels_;
+	std::map<int, audio::channel_ptr> channels_;
+
+	float smooth_pitch_ = 0.f;
 
 	util::clock<> clock_;
+	float time_ = 0.f;
 
 	gfx::painter painter_;
 };