feat(audio): add audio fade in/out and fix delta time naming

include/Cubed/app.hpp

@@ -38,7 +38,7 @@ public:
     static int start_cubed_application(int argc, char** argv);
 
     static unsigned int seed();
-    static float delte_time();
+    static float delta_time();
     static float get_fps();
 
     Camera& camera();
@@ -67,7 +67,7 @@ private:
 
     inline static double last_time = glfwGetTime();
     inline static double current_time = glfwGetTime();
-    inline static double delta_time = 0.0f;
+    inline static double dt = 0.0f;
     inline static double fps_time_count = 0.0f;
     inline static int frame_count = 0;
     inline static int fps = 0;

include/Cubed/audio/audio_buffer.hpp

@@ -12,9 +12,11 @@ public:
     AudioBuffer& operator=(AudioBuffer&&) = delete;
     ~AudioBuffer();
     ALuint buffer() const;
+    float duration() const;
 
 private:
     ALuint m_buffer = 0;
+    float m_duration = 0.0f;
     void set_data(const AudioData& data);
 };
 } // namespace Cubed

include/Cubed/audio/audio_engine.hpp

@@ -1,5 +1,6 @@
 #pragma once
 
+#include "Cubed/audio/audio_fade.hpp"
 #include "Cubed/audio/audio_source.hpp"
 #include "Cubed/audio/sound_manager.hpp"
 
@@ -24,15 +25,18 @@ public:
 
     void init();
     void play_bgm();
-    void update(glm::vec3 listener_pos);
+    void update_listener(glm::vec3 listener_pos);
+    void update(float dt);
 
 private:
     using SourcePool = std::unordered_map<std::string, ALuint>;
+    using FadeMap = std::unordered_map<std::string, AudioFade>;
     bool m_init{false};
     ALCdevice* device{nullptr};
     ALCcontext* context{nullptr};
     glm::vec3 listener_pos;
     std::unique_ptr<AudioSource> m_bgm;
+    FadeMap m_fade_map;
     SoundManager m_sounds;
 };
 } // namespace Cubed

include/Cubed/audio/audio_fade.hpp

@@ -0,0 +1,19 @@
+#pragma once
+#include "Cubed/audio/audio_source.hpp"
+namespace Cubed {
+class AudioFade {
+public:
+    AudioFade(AudioSource* source, float fade_in = 0.0f, float fade_out = 0.0f);
+    ~AudioFade();
+    void update();
+
+private:
+    AudioSource* m_source = nullptr;
+    float m_in_duration = 0.0f;
+    float m_out_duration = 0.0f;
+    float m_start_gain = 0.0f;
+    float m_end_gain = 0.0f;
+    bool m_fade_in = true;
+    bool m_active = true;
+};
+} // namespace Cubed

include/Cubed/audio/audio_source.hpp

@@ -11,16 +11,20 @@ public:
     AudioSource();
     ~AudioSource();
 
-    void set_buffer(const AudioBuffer& buffer);
+    void set_buffer_2d(const AudioBuffer& buffer);
     void set_loop(bool on = true);
-
+    void set_volume(float volume);
     void play();
     void stop();
     void pause();
-
+    float duration() const;
+    float current_time() const;
+    float volume() const;
     AudioState state();
 
 private:
     ALuint m_source = 0;
+    float m_volume = 1.0f;
+    float m_duration = 0.0f;
 };
 } // namespace Cubed

include/Cubed/tools/math_tools.hpp

@@ -104,6 +104,8 @@ inline float distance2(const glm::vec3& a, const glm::vec3& b) {
     return glm::dot(diff, diff);
 }
 
+inline float lerp(float a, float b, float t) { return a + t * (b - a); }
+
 } // namespace Math
 
 } // namespace Cubed

src/CMakeLists.txt

@@ -50,4 +50,5 @@ target_sources(${PROJECT_NAME}
         audio/audio_buffer.cpp
         audio/sound_manager.cpp
         audio/source_pool.cpp
+        audio/audio_fade.cpp
 )

src/app.cpp

@@ -329,9 +329,9 @@ static Gait player_gait = Gait::WALK;
 void App::update() {
     glfwPollEvents();
     current_time = glfwGetTime();
-    delta_time = current_time - last_time;
+    dt = current_time - last_time;
     last_time = current_time;
-    fps_time_count += delta_time;
+    fps_time_count += dt;
     frame_count++;
     if (fps_time_count >= 1.0f) {
         fps = static_cast<int>(frame_count / fps_time_count);
@@ -346,7 +346,7 @@ void App::update() {
             std::format("RSS: {}mb", Tools::get_current_rss() / (1024 * 1024)));
     }
     m_texture_manager.update();
-    m_client_world.update(delta_time);
+    m_client_world.update(dt);
     m_camera.update_move_camera();
     const auto& player = m_client_world.get_player();
     if (player_gait != player.get_gait()) {
@@ -359,8 +359,9 @@ void App::update() {
             m_renderer.update_fov(fov + 5.0f);
         }
     }
-    m_audio.update(m_camera.get_camera_pos());
+    m_audio.update_listener(m_camera.get_camera_pos());
-    m_renderer.update(delta_time);
+    m_audio.update(dt);
+    m_renderer.update(dt);
 }
 
 int App::start_cubed_application(int argc, char** argv) {
@@ -382,7 +383,7 @@ int App::start_cubed_application(int argc, char** argv) {
     return 1;
 }
 
-float App::delte_time() { return delta_time; }
+float App::delta_time() { return dt; }
 
 float App::get_fps() { return fps; }
 

src/audio/audio_buffer.cpp

@@ -8,6 +8,8 @@ AudioBuffer::AudioBuffer(const AudioData& data) {
 AudioBuffer::~AudioBuffer() { alDeleteBuffers(1, &m_buffer); }
 
 ALuint AudioBuffer::buffer() const { return m_buffer; }
+float AudioBuffer::duration() const { return m_duration; }
+
 void AudioBuffer::set_data(const AudioData& data) {
     ALenum format;
     if (data.channels == 1) {
@@ -17,6 +19,8 @@ void AudioBuffer::set_data(const AudioData& data) {
     }
     alBufferData(m_buffer, format, data.pcm.data(), data.pcm.size(),
                  data.sample_rate);
+    m_duration = static_cast<float>(data.pcm.size()) /
+                 (data.channels * data.sample_rate);
 }
 
 } // namespace Cubed

src/audio/audio_engine.cpp

@@ -33,7 +33,10 @@ void AudioEngine::init() {
 
     m_sounds.init();
     m_bgm = std::make_unique<AudioSource>();
-    m_bgm->set_buffer(m_sounds.get_buffer("bgm/bgm001.mp3"));
+    m_bgm->set_buffer_2d(m_sounds.get_buffer("bgm/bgm001.mp3"));
+
+    m_fade_map.try_emplace("bgm", m_bgm.get(), 5.0f, 2.0f);
+
     Logger::info("Audio Engine Init Success");
 
     m_init = true;
@@ -41,6 +44,11 @@ void AudioEngine::init() {
 
 void AudioEngine::play_bgm() { m_bgm->play(); }
 
-void AudioEngine::update(glm::vec3 listener_pos) {}
+void AudioEngine::update_listener(glm::vec3 listener_pos) {}
+void AudioEngine::update(float dt) {
 
+    for (auto& [key, fade] : m_fade_map) {
+        fade.update();
+    }
+}
 } // namespace Cubed

src/audio/audio_fade.cpp

@@ -0,0 +1,62 @@
+#include "Cubed/audio/audio_fade.hpp"
+
+#include <algorithm>
+#include <cmath>
+
+namespace Cubed {
+AudioFade::AudioFade(AudioSource* source, float fade_in, float fade_out)
+    : m_source(source), m_in_duration(fade_in), m_out_duration(fade_out) {
+    if (!m_source) {
+        m_active = false;
+        return;
+    }
+    m_start_gain = 0.0f;
+    m_end_gain = m_source->volume();
+    m_source->set_volume(0.0f);
+}
+AudioFade::~AudioFade() {}
+void AudioFade::update() {
+    if (!m_active || !m_source) {
+        return;
+    }
+
+    if (m_fade_in) {
+        float t =
+            std::clamp(m_source->current_time() / m_in_duration, 0.0f, 1.0f);
+
+        // Ease Out Sine
+        t = std::sin(t * std::numbers::pi_v<float> * 0.5f);
+
+        float gain = std::lerp(m_start_gain, m_end_gain, t);
+        m_source->set_volume(gain);
+        if (t >= 1.0f) {
+            m_source->set_volume(m_end_gain);
+            m_fade_in = false;
+            m_start_gain = m_end_gain;
+            m_end_gain = 0.0f;
+        }
+    } else {
+        float start_time =
+            std::max(0.0f, m_source->duration() - m_out_duration);
+
+        if (m_source->current_time() < start_time) {
+            return;
+        }
+
+        float elapsed = m_source->current_time() - start_time;
+
+        float t = std::clamp(elapsed / m_out_duration, 0.0f, 1.0f);
+
+        // Smoothstep
+        t = t * t * (3.0f - 2.0f * t);
+
+        float gain = std::lerp(m_start_gain, m_end_gain, t);
+        m_source->set_volume(gain);
+
+        if (t >= 1.0f) {
+            m_source->set_volume(m_end_gain);
+            m_active = false;
+        }
+    }
+}
+} // namespace Cubed

src/audio/audio_source.cpp

@@ -1,5 +1,7 @@
 #include "Cubed/audio/audio_source.hpp"
 
+#include "Cubed/tools/log.hpp"
+
 #include <stdexcept>
 
 namespace Cubed {
@@ -11,11 +13,14 @@ AudioSource::~AudioSource() {
     }
 }
 
-void AudioSource::set_buffer(const AudioBuffer& buffer) {
+void AudioSource::set_buffer_2d(const AudioBuffer& buffer) {
     if (state() == AudioState::PLAYING) {
         stop();
     }
+    m_duration = buffer.duration();
     alSourcei(m_source, AL_BUFFER, buffer.buffer());
+    alSourcei(m_source, AL_SOURCE_RELATIVE, AL_TRUE);
+    alSource3f(m_source, AL_POSITION, 0, 0, 0);
 }
 
 void AudioSource::set_loop(bool on) {
@@ -26,11 +31,28 @@ void AudioSource::set_loop(bool on) {
     }
 }
 
+void AudioSource::set_volume(float volume) {
+    if (volume > 1.0f) {
+        Logger::error("Volume {} is too large", volume);
+        return;
+    }
+    m_volume = volume;
+    alSourcef(m_source, AL_GAIN, volume);
+}
+
 void AudioSource::play() { alSourcePlay(m_source); }
 
 void AudioSource::stop() { alSourceStop(m_source); }
 void AudioSource::pause() { alSourcePause(m_source); }
 
+float AudioSource::duration() const { return m_duration; }
+float AudioSource::current_time() const {
+    ALfloat sec = 0.0f;
+    alGetSourcef(m_source, AL_SEC_OFFSET, &sec);
+    return static_cast<float>(sec);
+}
+float AudioSource::volume() const { return m_volume; }
+
 AudioState AudioSource::state() {
     ALint state;
     alGetSourcei(m_source, AL_SOURCE_STATE, &state);