feat(audio): add underwater low-pass filter effect

include/Cubed/audio/audio_engine.hpp

@@ -35,6 +35,8 @@ public:
     void update();
     void reload_config();
 
+    void underwater_change(bool underwater);
+
     float& bgm_target_volume();
 
 private:
@@ -47,8 +49,10 @@ private:
     FadeMap m_fade_map;
     SoundManager m_sounds;
     std::shared_ptr<SourcePool> m_pool;
-
+    bool m_efx_supported = false;
+    bool m_underwater = false;
     float m_music_volume = 1.0f;
     float m_sfx_volume = 1.0f;
+    std::unique_ptr<AudioFilter> m_low_pass_filter;
 };
 } // namespace Cubed

include/Cubed/audio/audio_filter.hpp

@@ -0,0 +1,19 @@
+#pragma once
+#include <AL/al.h>
+namespace Cubed {
+class AudioFilter {
+public:
+    AudioFilter();
+    AudioFilter(const AudioFilter&) = delete;
+    AudioFilter(AudioFilter&&) = delete;
+    AudioFilter& operator=(const AudioFilter&) = delete;
+    AudioFilter& operator=(AudioFilter&&) = delete;
+    ~AudioFilter();
+
+    void set_lowpass(float gain, float gain_hf);
+    ALuint filter() const;
+
+private:
+    ALuint m_filter = 0;
+};
+} // namespace Cubed

include/Cubed/audio/audio_source.hpp

@@ -1,5 +1,6 @@
 #pragma once
 #include "Cubed/audio/audio_buffer.hpp"
+#include "Cubed/audio/audio_filter.hpp"
 
 #include <AL/al.h>
 #include <glm/glm.hpp>
@@ -34,6 +35,9 @@ public:
     bool in_use() const;
     void reset();
 
+    void set_filter(const AudioFilter& filter);
+    void clear_filter();
+
 private:
     ALuint m_source = 0;
     float m_target_volume = 1.0f;

include/Cubed/audio/source_pool.hpp

@@ -16,6 +16,8 @@ public:
 
     void update();
     AudioSource* acquire();
+
+    std::vector<AudioSource>& sources();
 };
 
 } // namespace Cubed

src/CMakeLists.txt

@@ -51,4 +51,5 @@ target_sources(${PROJECT_NAME}
         audio/sound_manager.cpp
         audio/source_pool.cpp
         audio/audio_fade.cpp
+        audio/audio_filter.cpp
 )

src/audio/audio_engine.cpp

@@ -35,6 +35,21 @@ void AudioEngine::init() {
     }
     alcMakeContextCurrent(context);
 
+    if (!alcIsExtensionPresent(device, "ALC_EXT_EFX")) {
+        Logger::error("EFX not supported!");
+        m_efx_supported = false;
+    } else {
+        Logger::info("EFX supported!");
+        m_efx_supported = true;
+    }
+
+    if (m_efx_supported) {
+
+        m_low_pass_filter = std::make_unique<AudioFilter>();
+
+        m_low_pass_filter->set_lowpass(1.0f, 0.15f);
+    }
+
     alDistanceModel(AL_INVERSE_DISTANCE_CLAMPED);
     check_al_error();
 
@@ -78,6 +93,9 @@ void AudioEngine::change_bgm(const std::string& sound) {
     m_bgm->set_buffer_2d(m_sounds.get_buffer(sound));
     m_bgm->set_target_volume(m_music_volume);
     m_bgm->set_volume(m_music_volume);
+    if (m_efx_supported && m_underwater) {
+        m_bgm->set_filter(*m_low_pass_filter);
+    }
     auto it = m_fade_map.find("bgm");
     if (it != m_fade_map.end()) {
         it->second.reset();
@@ -99,6 +117,9 @@ void AudioEngine::play_3d(const std::string& sound, const glm::vec3& pos,
 
     try {
         auto& buffer = m_sounds.get_buffer(sound);
+        if (m_efx_supported && m_underwater) {
+            source->set_filter(*m_low_pass_filter);
+        }
         source->play_3d(buffer, pos);
     } catch (const std::exception& e) {
         if (check) {
@@ -121,6 +142,9 @@ void AudioEngine::play_2d(const std::string& sound, bool check) {
 
     try {
         auto& buffer = m_sounds.get_buffer(sound);
+        if (m_efx_supported && m_underwater) {
+            source->set_filter(*m_low_pass_filter);
+        }
         source->play_2d(buffer);
     } catch (const std::exception& e) {
         if (check) {
@@ -159,6 +183,29 @@ void AudioEngine::reload_config() {
     }
 }
 
+void AudioEngine::underwater_change(bool underwater) {
+    m_underwater = underwater;
+    if (!m_efx_supported) {
+        return;
+    }
+    if (!m_pool) {
+        return;
+    }
+    for (auto& source : m_pool->sources()) {
+        if (m_underwater) {
+            source.set_filter(*m_low_pass_filter);
+        } else {
+            source.clear_filter();
+        }
+    }
+    if (underwater) {
+        m_bgm->set_filter(*m_low_pass_filter);
+    } else {
+        m_bgm->clear_filter();
+    }
+    Logger::info("Under Water Change {}", m_underwater);
+}
+
 float& AudioEngine::bgm_target_volume() { return m_bgm->target_volume(); }
 
 } // namespace Cubed

src/audio/audio_filter.cpp

@@ -0,0 +1,22 @@
+#include "Cubed/audio/audio_filter.hpp"
+#ifndef AL_ALEXT_PROTOTYPES
+#define AL_ALEXT_PROTOTYPES
+#endif
+#include <AL/alc.h>
+#include <AL/efx.h>
+namespace Cubed {
+AudioFilter::AudioFilter() { alGenFilters(1, &m_filter); }
+AudioFilter::~AudioFilter() {
+    if (m_filter != 0) {
+        alDeleteFilters(1, &m_filter);
+    }
+}
+void AudioFilter::set_lowpass(float gain, float gain_hf) {
+    alFilteri(m_filter, AL_FILTER_TYPE, AL_FILTER_LOWPASS);
+    alFilterf(m_filter, AL_LOWPASS_GAIN, gain);
+    alFilterf(m_filter, AL_LOWPASS_GAINHF, gain_hf);
+}
+
+ALuint AudioFilter::filter() const { return m_filter; }
+
+} // namespace Cubed

src/audio/audio_source.cpp

@@ -3,6 +3,7 @@
 #include "Cubed/audio/audio_error.hpp"
 #include "Cubed/tools/log.hpp"
 
+#include <AL/efx.h>
 #include <algorithm>
 #include <stdexcept>
 
@@ -149,8 +150,17 @@ void AudioSource::reset() {
 
     alSourcef(m_source, AL_SEC_OFFSET, 0.0f);
 
+    clear_filter();
+
     m_duration = 0.0f;
     m_target_volume = 1.0f;
     m_using = false;
 }
+
+void AudioSource::set_filter(const AudioFilter& filter) {
+    alSourcei(m_source, AL_DIRECT_FILTER, filter.filter());
+}
+void AudioSource::clear_filter() {
+    alSourcei(m_source, AL_DIRECT_FILTER, AL_FILTER_NULL);
+}
 } // namespace Cubed

src/audio/source_pool.cpp

@@ -20,5 +20,5 @@ AudioSource* SourcePool::acquire() {
     }
     return nullptr;
 }
-
+std::vector<AudioSource>& SourcePool::sources() { return m_sources; }
 } // namespace Cubed

src/camera.cpp

@@ -49,8 +49,9 @@ void Camera::update_move_camera() {
     if (m_under_water != change) {
         m_under_water = change;
         m_player->set_underwater(m_under_water);
-        m_player->get_world().get_audio().play_2d(
-            "ambient/water/in_and_out_of_water.flac", true);
+        auto& audio = m_player->get_world().get_audio();
+        audio.play_2d("ambient/water/in_and_out_of_water.flac", true);
+        audio.underwater_change(m_under_water);
     }
 }