Implement music attenuation (#89)

Author: hyperbx

MarathonRecomp/app.cpp

@@ -4,6 +4,7 @@
 #include <kernel/function.h>
 #include <os/process.h>
 #include <os/logger.h>
+#include <patches/audio_patches.h>
 #include <ui/game_window.h>
 #include <user/config.h>
 #include <user/paths.h>
@@ -98,6 +99,8 @@ PPC_FUNC(sub_825EA610)
     // Allow variable FPS when config is not 60 FPS.
     App::s_pApp->m_pDoc->m_VFrame = Config::FPS != 60;
 
+    AudioPatches::Update(App::s_deltaTime);
+
     __imp__sub_825EA610(ctx, base);
 }
 

MarathonRecomp/patches/audio_patches.cpp

@@ -1,8 +1,9 @@
-#include <user/config.h>
+#include <api/Marathon.h>
 #include <kernel/function.h>
 #include <os/media.h>
 #include <os/version.h>
 #include <patches/audio_patches.h>
+#include <user/config.h>
 
 int AudioPatches::m_isAttenuationSupported = -1;
 
@@ -22,5 +23,28 @@ bool AudioPatches::CanAttenuate()
 #endif
 }
 
-// TODO (Hyper): implement music attenuation.
-void AudioPatches::Update(float deltaTime) {}
+void AudioPatches::Update(float deltaTime)
+{
+    auto pAudioEngine = Sonicteam::AudioEngineXenon::GetInstance();
+
+    if (!pAudioEngine)
+        return;
+
+    if (Config::MusicAttenuation && CanAttenuate())
+    {
+        auto time = 1.0f - expf(2.5f * -deltaTime);
+
+        if (os::media::IsExternalMediaPlaying())
+        {
+            pAudioEngine->m_MusicVolume = std::lerp(pAudioEngine->m_MusicVolume, 0.0f, time);
+        }
+        else
+        {
+            pAudioEngine->m_MusicVolume = std::lerp(pAudioEngine->m_MusicVolume, Config::MusicVolume, time);
+        }
+    }
+    else
+    {
+        pAudioEngine->m_MusicVolume = Config::MusicVolume;
+    }
+}