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