FixZBufferPrecision: greatly reduces z-fighting/distant object pop-in

Author: emoose

Outrun2006Tweaks.ini

@@ -2,23 +2,25 @@
 # Framelimit: The max framerate for the game to use.
 #  This will also override the fullscreen refresh rate that the game requests.
 #  Set to 0 to disable this framelimiter, in case you want to use an external one instead.
+#  (if game doesn't run at full framerate-limit setting, try checking with "DX/WINDOWED = 1" in outrun2006.ini)
 FramerateLimit = 60
 
-# FramerateLimitMode: Improve accuracy of the framerate limiter at a cost of higher CPU usage.
+# FramerateLimitMode: Improves accuracy of the framerate limiter at a cost of higher CPU usage.
+#  The default 0 should work fine for most people, but if you have issues it might be worth trying the accurate mode.
 #  0 = efficient mode
 #  1 = accurate mode
 FramerateLimitMode = 0
 
 # FramerateFastLoad: Unlimits framerate during load screens to help reduce load times.
 #  0 = disable
-#  1 = unlimit framerate
-#  2 = unlimit framerate & disable vsync (fastest but may cause screen flash)
+#  1 = unlimit framerate during load screens
+#  2 = unlimit framerate & disable vsync during load screens (fastest load times but may cause screen flash)
 FramerateFastLoad = 1
 
-# FramerateUnlockExperimental: Prevents game from speeding up when playing with FramerateLimit above 60FPS.
+# FramerateUnlockExperimental: Fixes game speeding up when playing with FramerateLimit above 60FPS.
 #  Works by forcing game to only update at 60Hz, while rendering is allowed to run at a higher rate.
-#  Though since game still runs at 60Hz internally this isn't as good as a true framerate unlock, but might still be useful for some.
-#  (certain textures/UI elements may animate faster at higher FPS, but gameplay should remain the same speed)
+#  Since game still runs at 60Hz internally this isn't as good as a true framerate unlock, but might still be useful for some.
+#  (some textures/UI elements may animate faster at higher FPS, but gameplay should remain the same speed)
 #  Should be fine to leave this enabled in most cases, but if you have issues feel free to disable this here.
 FramerateUnlockExperimental = true
 
@@ -53,11 +55,14 @@ AnisotropicFiltering = 16
 #  For best results use this with "DX/ANTIALIASING = 2" inside outrun2006.ini
 TransparencySupersampling = true
 
-# ScreenEdgeCullFix: Fixes issues with certain stage objects being culled out before they reach edge of screen when playing at non-4:3 aspect ratio.
+# ScreenEdgeCullFix: Fixes certain stage objects being culled out before they reach edge of screen, when playing at non-4:3 aspect ratio.
 ScreenEdgeCullFix = true
 
 # DisableVehicleLODs: Disables LODs on vehicles, reducing the ugly pop-in they have.
 DisableVehicleLODs = true
 
 # DisableStageCulling: Disables culling of certain stage objects, so most distant objects won't obviously pop in to view.
 DisableStageCulling = true
+
+# FixZBufferPrecision: Fixes Z-Buffer precision issues, heavily reducing z-fighting and distant object drawing issues (eg. signs/buildings will have much less pop-in)
+FixZBufferPrecision = true

README.md

@@ -3,13 +3,15 @@ A wrapper DLL that can patch in some minor fixes & tweaks into Outrun 2006: Coas
 
 ### Features
 - Game can now run in borderless windowed mode; mouse cursor will now be hidden while game is active
-- Adds a built-in framelimiter to prevent game from speeding up (along with an optional fix to allow higher FPS without speedup)
+- Adds a built-in framelimiter to prevent game from speeding up (along with an optional fix that can allow higher FPS without speedup)
 - Fixes objects being culled out before reaching edge of screen
 - Allows disabling vehicle LODs to reduce the ugly pop-in of them
 - Disables culling of certain stage objects
-- Can force anisotropic filtering level & enable transparency supersampling, greatly reducing aliasing around the edges of track. (set `DX/ANTIALIASING = 2` in outrun2006.ini for best results)
+- Fixes Z-buffer precision issues, greatly reducing z-fighting & distant object pop-in
+- Can force anisotropic filtering level & enable transparency supersampling, greatly reducing aliasing around the edges of the track. (set `DX/ANTIALIASING = 2` in outrun2006.ini for best results)
 - Automatically disables DPI scaling on the game window, fixing scaling issues with certain setups
-- Allows game to load in lens flare data from correct path when needed, fixing lens flare issues.
+- Fixes broken lens flare effect by making game load it from correct path
+- Heavily reduced load times by disabling framelimiter/vsync during load screens
 
 All the above can be toggled/customized via the Outrun2006Tweaks.ini file.
 
@@ -18,9 +20,9 @@ Since the game will still internally update at 60FPS this won't give as much ben
 (some things like animated textures & UI text also unfortunately have speed issues with it...)
 
 ### Setup
-Since the Steam/DVD releases are packed with ancient DRM that doesn't play well with DLL wrappers, a replacement game EXE is included with this tweaks pack.
+Since Steam/DVD releases are packed with ancient DRM that doesn't play well with DLL wrappers, this pack includes a replacement game EXE to run the game with.
 
-This EXE should be compatible with both the Steam release and the original DVD version.
+This EXE should be compatible with both the Steam release & the original DVD version, along with most OR2006 mods.
 
 To set it up just extract the files from the release ZIP into your `Outrun2006 Coast 2 Coast` folder, where `OR2006C2C.EXE` is located, replacing the original EXE.
 

src/dllmain.cpp

@@ -101,6 +101,7 @@ namespace Settings
 		ScreenEdgeCullFix = ini.Get("Graphics", "ScreenEdgeCullFix", std::move(ScreenEdgeCullFix));
 		DisableVehicleLODs = ini.Get("Graphics", "DisableVehicleLODs", std::move(DisableVehicleLODs));
 		DisableStageCulling = ini.Get("Graphics", "DisableStageCulling", std::move(DisableStageCulling));
+		FixZBufferPrecision = ini.Get("Graphics", "FixZBufferPrecision", std::move(FixZBufferPrecision));
 
 		return true;
 	}

src/game.hpp

@@ -52,3 +52,15 @@ typedef struct tagSphere
 	float f2;
 	float f3;
 } Sphere;
+
+typedef struct tgaEvWorkCamera // [sic]
+{
+	uint8_t unk_0[0xBC];
+	float perspective_znear_BC;
+	float perspective_zfar_C0;
+	uint8_t unk_C4[0xC];
+	uint8_t unk_D0[0x34A - 0xD0];
+	char camera_mode_34A;
+	uint8_t unk_34B[0x5];
+	uint8_t unk_350[0x64];
+} EvWorkCamera;

src/hooks_graphics.cpp

@@ -160,6 +160,47 @@ class DisableVehicleLODs : public Hook
 };
 DisableVehicleLODs DisableVehicleLODs::instance;
 
+class FixZBufferPrecision : public Hook
+{
+	const static int CalcCameraMatrix_Addr = 0x84BD0;
+
+	inline static SafetyHookInline hook_orig = {};
+
+	static void destination(EvWorkCamera* camera)
+	{
+		// improve z-buffer precision by increasing znear
+		// game default is 0.1, which reduces precision of far objects massively, causing z-fighting and objects not drawing properly
+		
+		if (camera->camera_mode_34A == 2) // only set znear to 1 if we're in the third-person cam mode
+			camera->perspective_znear_BC = 1.0f;
+		else
+			camera->perspective_znear_BC = 0.3f; // 0.3 seems fine for in-car view, doesn't improve as much as 1.0f but still better than 0.1f
+
+		hook_orig.call(camera);
+	}
+
+public:
+	std::string_view description() override
+	{
+		return "FixZBufferPrecision";
+	}
+
+	bool validate() override
+	{
+		return Settings::FixZBufferPrecision;
+	}
+
+	bool apply() override
+	{
+		hook_orig = safetyhook::create_inline(Module::exe_ptr(CalcCameraMatrix_Addr), destination);
+
+		return !!hook_orig;
+	}
+
+	static FixZBufferPrecision instance;
+};
+FixZBufferPrecision FixZBufferPrecision::instance;
+
 class TransparencySupersampling : public Hook
 {
 	const static int DeviceInitHookAddr = 0xEC2F;

src/plugin.hpp

@@ -51,6 +51,7 @@ namespace Settings
 	inline bool ScreenEdgeCullFix = true;
 	inline bool DisableVehicleLODs = true;
 	inline bool DisableStageCulling = true;
+	inline bool FixZBufferPrecision = true;
 }
 
 namespace Util

src/resource.h

@@ -14,8 +14,8 @@
 #endif
 
 #define MODULE_VERSION_MAJOR 0
-#define MODULE_VERSION_MINOR 1
-#define MODULE_VERSION_BUILD 1
+#define MODULE_VERSION_MINOR 2
+#define MODULE_VERSION_BUILD 0
 #define MODULE_VERSION_REVISION 0
 
 #define STR(value) #value