From 5f9f395d91c4dee2e2e625c1be23a52ae35b5fb3 Mon Sep 17 00:00:00 2001
From: Hyper <34012267+hyperbx@users.noreply.github.com>
Date: Thu, 14 Aug 2025 09:57:27 +0100
Subject: [PATCH] Use dynamic physics update rate above 120 FPS

---
 MarathonRecomp/CMakeLists.txt                      |  1 +
 MarathonRecomp/api/Marathon.h                      |  3 +++
 MarathonRecomp/api/Sonicteam/GameImp.h             |  9 +++++++++
 MarathonRecomp/api/Sonicteam/GameImp.inl           |  8 ++++++++
 .../api/Sonicteam/SoX/Physics/Havok/WorldHavok.h   | 14 ++++++++++++++
 MarathonRecomp/api/Sonicteam/SoX/Physics/World.h   |  9 +++++++++
 MarathonRecomp/api/Sonicteam/SoX/RefCountObject.h  | 11 +++++++++++
 MarathonRecomp/patches/fps_patches.cpp             | 14 ++++++++++++++
 8 files changed, 69 insertions(+)
 create mode 100644 MarathonRecomp/api/Sonicteam/GameImp.inl
 create mode 100644 MarathonRecomp/api/Sonicteam/SoX/Physics/Havok/WorldHavok.h
 create mode 100644 MarathonRecomp/api/Sonicteam/SoX/Physics/World.h
 create mode 100644 MarathonRecomp/api/Sonicteam/SoX/RefCountObject.h
 create mode 100644 MarathonRecomp/patches/fps_patches.cpp

diff --git a/MarathonRecomp/CMakeLists.txt b/MarathonRecomp/CMakeLists.txt
index 76e2586fe..1f53add8b 100644
--- a/MarathonRecomp/CMakeLists.txt
+++ b/MarathonRecomp/CMakeLists.txt
@@ -138,6 +138,7 @@ set(MARATHON_RECOMP_PATCHES_CXX_SOURCES
     "patches/aspect_ratio_patches.cpp"
     "patches/audio_patches.cpp"
     "patches/camera_patches.cpp"
+    "patches/fps_patches.cpp"
     "patches/frontend_listener.cpp"
     "patches/misc_patches.cpp"
     "patches/player_patches.cpp"
diff --git a/MarathonRecomp/api/Marathon.h b/MarathonRecomp/api/Marathon.h
index ec5ec14c8..49b8141f8 100644
--- a/MarathonRecomp/api/Marathon.h
+++ b/MarathonRecomp/api/Marathon.h
@@ -56,6 +56,9 @@
 #include "Sonicteam/SoX/Engine/Task.h"
 #include "Sonicteam/SoX/MessageReceiver.h"
 #include "Sonicteam/SoX/Object.h"
+#include "Sonicteam/SoX/Physics/Havok/WorldHavok.h"
+#include "Sonicteam/SoX/Physics/World.h"
+#include "Sonicteam/SoX/RefCountObject.h"
 #include "Sonicteam/System/CreateStatic.h"
 #include "Sonicteam/System/Singleton.h"
 #include "Sonicteam/TitleTask.h"
diff --git a/MarathonRecomp/api/Sonicteam/GameImp.h b/MarathonRecomp/api/Sonicteam/GameImp.h
index 2dc4855a1..dde0e1224 100644
--- a/MarathonRecomp/api/Sonicteam/GameImp.h
+++ b/MarathonRecomp/api/Sonicteam/GameImp.h
@@ -1,6 +1,7 @@
 #pragma once
 
 #include <Marathon.inl>
+#include <Sonicteam/SoX/Physics/World.h>
 
 namespace Sonicteam
 {
@@ -29,5 +30,13 @@ namespace Sonicteam
 
         MARATHON_INSERT_PADDING(0xE3C);
         PlayerData m_PlayerData[4];
+        MARATHON_INSERT_PADDING(0xA4C);
+        xpointer<SoX::Physics::World> m_pPhysicsWorld;
+        xpointer<void> m_pMyCollisionFilter;
+
+        template <typename T>
+        inline T* GetPhysicsWorld();
     };
 }
+
+#include <Sonicteam/GameImp.inl>
diff --git a/MarathonRecomp/api/Sonicteam/GameImp.inl b/MarathonRecomp/api/Sonicteam/GameImp.inl
new file mode 100644
index 000000000..ed1de103f
--- /dev/null
+++ b/MarathonRecomp/api/Sonicteam/GameImp.inl
@@ -0,0 +1,8 @@
+namespace Sonicteam
+{
+    template <typename T>
+    inline T* GameImp::GetPhysicsWorld()
+    {
+        return (T*)m_pPhysicsWorld.get();
+    }
+}
diff --git a/MarathonRecomp/api/Sonicteam/SoX/Physics/Havok/WorldHavok.h b/MarathonRecomp/api/Sonicteam/SoX/Physics/Havok/WorldHavok.h
new file mode 100644
index 000000000..8415b9c7d
--- /dev/null
+++ b/MarathonRecomp/api/Sonicteam/SoX/Physics/Havok/WorldHavok.h
@@ -0,0 +1,14 @@
+#pragma once
+
+#include <Marathon.inl>
+#include <Sonicteam/SoX/Physics/World.h>
+
+namespace Sonicteam::SoX::Physics::Havok
+{
+    class WorldHavok : public World
+    {
+    public:
+        MARATHON_INSERT_PADDING(0x18);
+        bool m_IsDynamicUpdateRate;
+    };
+}
diff --git a/MarathonRecomp/api/Sonicteam/SoX/Physics/World.h b/MarathonRecomp/api/Sonicteam/SoX/Physics/World.h
new file mode 100644
index 000000000..7e786fd12
--- /dev/null
+++ b/MarathonRecomp/api/Sonicteam/SoX/Physics/World.h
@@ -0,0 +1,9 @@
+#pragma once
+
+#include <Marathon.inl>
+#include <Sonicteam/SoX/RefCountObject.h>
+
+namespace Sonicteam::SoX::Physics
+{
+    class World : public RefCountObject {};
+}
diff --git a/MarathonRecomp/api/Sonicteam/SoX/RefCountObject.h b/MarathonRecomp/api/Sonicteam/SoX/RefCountObject.h
new file mode 100644
index 000000000..4f006d9b7
--- /dev/null
+++ b/MarathonRecomp/api/Sonicteam/SoX/RefCountObject.h
@@ -0,0 +1,11 @@
+#pragma once
+
+namespace Sonicteam::SoX
+{
+    class RefCountObject
+    {
+    public:
+        xpointer<void> m_pVftable;
+        be<uint32_t> m_ReferenceCount;
+    };
+}
diff --git a/MarathonRecomp/patches/fps_patches.cpp b/MarathonRecomp/patches/fps_patches.cpp
new file mode 100644
index 000000000..5067635d3
--- /dev/null
+++ b/MarathonRecomp/patches/fps_patches.cpp
@@ -0,0 +1,14 @@
+#include <api/Marathon.h>
+#include <user/config.h>
+
+// Sonicteam::SoX::Physics::Havok::WorldHavok::Update
+PPC_FUNC_IMPL(__imp__sub_82587AA8);
+PPC_FUNC(sub_82587AA8)
+{
+    auto pPhysicsWorld = (Sonicteam::SoX::Physics::Havok::WorldHavok*)(base + ctx.r3.u32);
+
+    // Use dynamic update rate if the FPS exceeds the fixed rate.
+    pPhysicsWorld->m_IsDynamicUpdateRate = Config::FPS > 120;
+
+    __imp__sub_82587AA8(ctx, base);
+}