popn: fix subscreen redraw option causing graphical glitches (#854)

## Link to GitHub Issue or related Pull Request, if one exists
#0

## Description of change
Old behavior: Forced redraw presented the subscreen every main frame,
even when the game already presented it, causing duplicate presents and
tearing in popn (was fine in sdvx)

New behavior: Forced redraw acts as a fallback, presenting only when the
game skips or fails a subscreen update.

## Testing
Popn - no more glitching
Nabla - no regression

src/spice2x/build/manifest.manifest

@@ -6,6 +6,7 @@
         <asmv3:windowsSettings xmlns="http://schemas.microsoft.com/SMI/2005/WindowsSettings">
             <dpiAwareness xmlns="http://schemas.microsoft.com/SMI/2016/WindowsSettings">PerMonitorV2</dpiAwareness>
             <dpiAware>true</dpiAware>
+            <activeCodePage xmlns="http://schemas.microsoft.com/SMI/2019/WindowsSettings">Legacy</activeCodePage>
         </asmv3:windowsSettings>
     </asmv3:application>
     <dependency>

src/spice2x/games/iidx/iidx.cpp

@@ -58,7 +58,7 @@ namespace games::iidx {
 
     // settings
     bool FLIP_CAMS = false;
-    std::optional<bool> DISABLE_CAMS;
+    cab_camera_access_mode CAB_CAMERA_ACCESS = cab_camera_access_mode::automatic;
     bool TDJ_CAMERA = false;
     bool TDJ_CAMERA_PREFER_16_9 = true;
     bool TDJ_MODE = false;
@@ -424,10 +424,7 @@ namespace games::iidx {
                 "RegQueryValueExA", RegQueryValueExA_hook, avs::game::DLL_INSTANCE);
 
         // check if cam hook should be enabled
-        if (!DISABLE_CAMS.has_value()) {
-            log_fatal("iidx", "assertion failure - DISABLE_CAMS not set during attach");
-        }
-        if (!DISABLE_CAMS.value()) {
+        if (CAB_CAMERA_ACCESS == cab_camera_access_mode::legacy) {
             init_legacy_camera_hook(FLIP_CAMS);
         }
 
@@ -454,19 +451,10 @@ namespace games::iidx {
             SetEnvironmentVariable("SCREEN_MODE", SCREEN_MODE.value().c_str());
         }
 
-        // check for cab camera access for the second time (first time was in launcher.cpp)
-        // this time, we are inside -iidx module hook, which means the user is likely NOT on a cab
-        // therefore, start with cams OFF by default, and allow user to forcibly override to ON
-        if (!games::iidx::DISABLE_CAMS.has_value()) {
-            games::iidx::DISABLE_CAMS = true;
-            if (options->at(launcher::Options::IIDXCabCamAccess).is_active() &&
-                options->at(launcher::Options::IIDXCabCamAccess).value_text() == "on") {
-                games::iidx::DISABLE_CAMS = false;
-            }
-            if (games::iidx::DISABLE_CAMS.value()) {
-                log_misc("iidx", "CONNECT_CAMERA env var set to 0");
-                SetEnvironmentVariable("CONNECT_CAMERA", "0");
-            }
+        // auto with iidx module means turn off camera (non-cab use)
+        if (CAB_CAMERA_ACCESS == cab_camera_access_mode::automatic) {
+            log_misc("iidx", "CONNECT_CAMERA env var set to 0");
+            SetEnvironmentVariable("CONNECT_CAMERA", "0");
         }
 
         // windowed subscreen, enabled by default, unless turned off by user

src/spice2x/games/iidx/iidx.h

@@ -11,6 +11,13 @@
 
 namespace games::iidx {
 
+    enum class cab_camera_access_mode {
+        automatic,
+        off,
+        on,
+        legacy,
+    };
+
     enum class iidx_aio_emulation_state {
         unknown,
         bi2a_com2,
@@ -20,7 +27,7 @@ namespace games::iidx {
     // settings
 
     extern bool FLIP_CAMS;
-    extern std::optional<bool> DISABLE_CAMS;
+    extern cab_camera_access_mode CAB_CAMERA_ACCESS;
     extern bool TDJ_CAMERA;
     extern bool TDJ_CAMERA_PREFER_16_9;
     extern std::optional<std::string> TDJ_CAMERA_OVERRIDE;

src/spice2x/hooks/graphics/backends/d3d9/d3d9_backend.cpp

@@ -1,5 +1,6 @@
 #include "d3d9_backend.h"
 
+#include <atomic>
 #include <cassert>
 #include <memory>
 #include <thread>
@@ -113,6 +114,12 @@ static Direct3DCreate9On12Ex_t Direct3DCreate9On12Ex_orig = nullptr;
 static bool ATTEMPTED_SUB_SWAP_CHAIN_ACQUIRE = false;
 static IDirect3DSwapChain9 *SUB_SWAP_CHAIN = nullptr;
 
+// main and subscreen presents may occur on different threads.
+static std::atomic_bool SUBSCREEN_PRESENTED_SINCE_LAST_MAIN = false;
+
+// do not mistake the fallback Present below for a game-originated Present.
+static thread_local bool SUBSCREEN_FORCE_REDRAW_IN_PROGRESS = false;
+
 static void graphics_d3d9_ldj_init_sub_screen(
         IDirect3DDevice9Ex *device,
         D3DPRESENT_PARAMETERS *present_params,
@@ -1445,6 +1452,12 @@ IDirect3DSurface9 *graphics_d3d9_ldj_get_sub_screen() {
     return surface;
 }
 
+void graphics_d3d9_notify_subscreen_present() {
+    if (SUBSCREEN_FORCE_REDRAW && !SUBSCREEN_FORCE_REDRAW_IN_PROGRESS) {
+        SUBSCREEN_PRESENTED_SINCE_LAST_MAIN.store(true, std::memory_order_relaxed);
+    }
+}
+
 static void graphics_d3d9_ldj_on_present(IDirect3DDevice9 *wrapped_device) {
     // iidx/sdvx
     int swapchain = 1;
@@ -1472,8 +1485,16 @@ static void graphics_d3d9_ldj_on_present(IDirect3DDevice9 *wrapped_device) {
         //
         // early versions of popn HC needs this as well, but not on by default as it can cause
         // graphical glitches on some GPUs 
-        if (GRAPHICS_WINDOWED || SUBSCREEN_FORCE_REDRAW) {
+        //
+        // treat forced redraw as a fallback so it does not duplicate a successful game present.
+
+        const bool force_redraw = SUBSCREEN_FORCE_REDRAW &&
+            !SUBSCREEN_PRESENTED_SINCE_LAST_MAIN.exchange(false, std::memory_order_relaxed);
+
+        if (GRAPHICS_WINDOWED || force_redraw) {
+            SUBSCREEN_FORCE_REDRAW_IN_PROGRESS = true;
             SUB_SWAP_CHAIN->Present(nullptr, nullptr, nullptr, nullptr, 0);
+            SUBSCREEN_FORCE_REDRAW_IN_PROGRESS = false;
         }
     }
 }

src/spice2x/hooks/graphics/backends/d3d9/d3d9_backend.h

@@ -15,6 +15,8 @@ void graphics_d3d9_on_present(
     IDirect3DDevice9 *device,
     IDirect3DDevice9 *wrapped_device);
 
+void graphics_d3d9_notify_subscreen_present();
+
 IDirect3DSurface9 *graphics_d3d9_ldj_get_sub_screen();
 
 struct WrappedIDirect3D9 : IDirect3D9Ex {

src/spice2x/hooks/graphics/backends/d3d9/d3d9_device.cpp

@@ -134,6 +134,10 @@ ULONG STDMETHODCALLTYPE WrappedIDirect3DDevice9::Release() {
             this->main_swapchain->Release();
             this->main_swapchain = nullptr;
         }
+        if (this->implicit_sub_swapchain) {
+            this->implicit_sub_swapchain->Release();
+            this->implicit_sub_swapchain = nullptr;
+        }
         for (auto &sc : this->sub_swapchain) {
             if (sc) {
                 sc->Release();
@@ -487,6 +491,24 @@ HRESULT STDMETHODCALLTYPE WrappedIDirect3DDevice9::GetSwapChain(
             fake_sub_swapchain[0]->AddRef();
             *ppSwapChain = static_cast<IDirect3DSwapChain9 *>(fake_sub_swapchain[0]);
 
+            graphics_screens_register(iSwapChain);
+            return D3D_OK;
+        } else if (SUBSCREEN_FORCE_REDRAW) {
+            // store implicit sub swap chain
+            if (!implicit_sub_swapchain) {
+                IDirect3DSwapChain9 *real_swapchain = nullptr;
+                HRESULT ret = pReal->GetSwapChain(iSwapChain, &real_swapchain);
+                if (FAILED(ret)) {
+                    return ret;
+                }
+
+                implicit_sub_swapchain = new WrappedIDirect3DSwapChain9(this, real_swapchain);
+                implicit_sub_swapchain->should_run_hooks = false;
+            }
+
+            implicit_sub_swapchain->AddRef();
+            *ppSwapChain = static_cast<IDirect3DSwapChain9 *>(implicit_sub_swapchain);
+
             graphics_screens_register(iSwapChain);
             return D3D_OK;
         }

src/spice2x/hooks/graphics/backends/d3d9/d3d9_device.h

@@ -262,6 +262,7 @@ struct WrappedIDirect3DDevice9 : IDirect3DDevice9Ex {
     std::atomic_ulong refs = 1;
 
     WrappedIDirect3DSwapChain9 *main_swapchain = nullptr;
+    WrappedIDirect3DSwapChain9 *implicit_sub_swapchain = nullptr;
     WrappedIDirect3DSwapChain9 *sub_swapchain[3] = { nullptr, nullptr, nullptr };
     FakeIDirect3DSwapChain9 *fake_sub_swapchain[3] = { nullptr, nullptr, nullptr };
 

src/spice2x/hooks/graphics/backends/d3d9/d3d9_swapchain.cpp

@@ -96,6 +96,12 @@ HRESULT STDMETHODCALLTYPE WrappedIDirect3DSwapChain9::Present(const RECT *pSourc
             pDirtyRegion,
             dwFlags);
 
+    // a successful game subscreen present suppresses the next forced fallback present.
+    if (SUCCEEDED(result) &&
+        (this == pDev->implicit_sub_swapchain || this == pDev->sub_swapchain[0])) {
+        graphics_d3d9_notify_subscreen_present();
+    }
+
     // Some drivers report S_PRESENT_MODE_CHANGED after Windows moves the portrait SMALL
     // head into the requested exclusive mode, leaving both group heads black. Toggle SMALL
     // through another supported mode and restore it once, then retry the interrupted MAIN

src/spice2x/hooks/lang.cpp

@@ -13,7 +13,9 @@
 #include "avs/game.h"
 #include "games/iidx/iidx.h"
 #include "games/gitadora/gitadora.h"
+#include "games/popn/popn.h"
 #include "games/sdvx/sdvx.h"
+#include "util/deferlog.h"
 #include "util/detour.h"
 #include "util/logging.h"
 #include "util/utils.h"
@@ -29,6 +31,7 @@ static decltype(GetLocaleInfoEx) *GetLocaleInfoEx_orig = nullptr;
 #ifdef SPICE64
 static decltype(GetSystemDefaultLCID) *GetSystemDefaultLCID_orig = nullptr;
 static decltype(IsDBCSLeadByte) *IsDBCSLeadByte_orig = nullptr;
+static decltype(IsDBCSLeadByteEx) *IsDBCSLeadByteEx_orig = nullptr;
 static decltype(WideCharToMultiByte) *WideCharToMultiByte_orig = nullptr;
 static decltype(GetLocaleInfoA) *GetLocaleInfoA_orig = nullptr;
 static decltype(GetThreadLocale) *GetThreadLocale_orig = nullptr;
@@ -182,9 +185,30 @@ static BOOL WINAPI IsDBCSLeadByte_hook (
     BYTE TestChar
     )
 {
+    if (IsDBCSLeadByteEx_orig) {
+        return IsDBCSLeadByteEx_orig(CODEPAGE_SHIFT_JIS, TestChar);
+    }
+
     return IsDBCSLeadByteEx(CODEPAGE_SHIFT_JIS, TestChar);
 }
 
+static BOOL WINAPI IsDBCSLeadByteEx_hook(
+    UINT CodePage,
+    BYTE TestChar)
+{
+    switch (CodePage) {
+        case CP_ACP:
+        case CP_THREAD_ACP:
+            CodePage = CODEPAGE_SHIFT_JIS;
+            break;
+
+        default:
+            break;
+    }
+
+    return IsDBCSLeadByteEx_orig(CodePage, TestChar);
+}
+
 static
 int
 WINAPI
@@ -250,6 +274,18 @@ GetLocaleInfoA_hook(
 void hooks::lang::early_init() {
     log_info("hooks::lang", "early initialization");
 
+    const auto native_code_page = GetACP();
+    if (native_code_page == CP_UTF8) {
+        log_warning(
+            "hooks::lang",
+            "Windows is using UTF-8 as the system code page; "
+            "some games may render text incorrectly or behave unexpectedly");
+
+        deferredlogs::defer_error_messages({
+            "Windows is using UTF-8 as the system code page",
+            "    some games may render text incorrectly or behave unexpectedly"});
+    }
+
     // hooking these two functions fixes the jubeat mojibake
     detour::trampoline_try("kernel32.dll", "GetACP", GetACP_hook, &GetACP_orig);
     detour::trampoline_try("kernel32.dll", "GetOEMCP", GetOEMCP_hook, &GetOEMCP_orig);
@@ -315,6 +351,15 @@ void hooks::lang::early_init() {
             WideCharToMultiByte_hook,
             &WideCharToMultiByte_orig);
     }
+
+    if (games::popn::is_pikapika_model() && native_code_page == CP_UTF8) {
+        detour::trampoline_try(
+            "kernel32.dll",
+            "IsDBCSLeadByteEx",
+            IsDBCSLeadByteEx_hook,
+            &IsDBCSLeadByteEx_orig);
+    }
+
 #endif
 
 }

src/spice2x/launcher/launcher.cpp

@@ -5,7 +5,6 @@
 
 #include <cmath>
 #include <cstdlib>
-#include <assert.h>
 #include <shlwapi.h>
 #include <windows.h>
 #include <cfg/configurator.h>
@@ -524,22 +523,25 @@ int main_implementation(int argc, char *argv[]) {
         games::iidx::FLIP_CAMS = true;
     }
 
-    // IIDX CONNECT_CAMERA logic here for cases where user is running without -iidx module
-    // for now, we assume that user may be running on a cab
-    // (games::iidx::DISABLE_CAMS starts out as false unless user overrides)
-    // we will check again in IIDX module with a different default
-    assert(!games::iidx::DISABLE_CAMS.has_value());
-    if (options[launcher::Options::IIDXDisableCameras].value_bool()) {
-        games::iidx::DISABLE_CAMS = true;
+    // Resolve the IIDX camera policy here so it also applies without the -iidx module.
+    const auto &cab_camera_access = options[launcher::Options::IIDXCabCamAccess];
+    if (cab_camera_access.is_active()) {
+        const auto value = cab_camera_access.value_text();
+        if (value == "off") {
+            games::iidx::CAB_CAMERA_ACCESS = games::iidx::cab_camera_access_mode::off;
+        } else if (value == "on") {
+            games::iidx::CAB_CAMERA_ACCESS = games::iidx::cab_camera_access_mode::on;
+        } else if (value == "legacy") {
+            games::iidx::CAB_CAMERA_ACCESS = games::iidx::cab_camera_access_mode::legacy;
+        }
     }
-    if (options[launcher::Options::IIDXCabCamAccess].is_active() &&
-        options[launcher::Options::IIDXCabCamAccess].value_text() == "off") {
-        games::iidx::DISABLE_CAMS = true;
+
+    if (options[launcher::Options::IIDXDisableCameras].value_bool()) {
+        games::iidx::CAB_CAMERA_ACCESS = games::iidx::cab_camera_access_mode::off;
     }
     if (options[launcher::Options::IIDXCamHook].value_bool()) {
         games::iidx::TDJ_CAMERA = true;
-        // Disable legacy behaviour to avoid conflict
-        games::iidx::DISABLE_CAMS = true;
+        games::iidx::CAB_CAMERA_ACCESS = games::iidx::cab_camera_access_mode::off;
     }
     // CONNECT_CAMERA env var will be set once logging is enabled
 
@@ -1717,14 +1719,13 @@ int main_implementation(int argc, char *argv[]) {
         GRAPHICS_FS_ORIENTATION_SWAP = true;
     }
 
-
-    // for cab usage - set environment variables (outside of -iidx module)
-    if (games::iidx::DISABLE_CAMS.has_value() &&
-        games::iidx::DISABLE_CAMS.value() &&
+    // apply an explicit off outside of the -iidx module so it also works on cabinets.
+    if (games::iidx::CAB_CAMERA_ACCESS == games::iidx::cab_camera_access_mode::off &&
         !cfg::CONFIGURATOR_STANDALONE) {
         log_misc("launcher::iidx", "CONNECT_CAMERA env var set to 0");
         SetEnvironmentVariable("CONNECT_CAMERA", "0");
     }
+
     if (games::iidx::SOUND_OUTPUT_DEVICE.has_value() &&
         games::iidx::SOUND_OUTPUT_DEVICE.value() != "auto" &&
         !cfg::CONFIGURATOR_STANDALONE) {

src/spice2x/launcher/options.cpp

@@ -640,17 +640,21 @@ static const std::vector<OptionDefinition> OPTION_DEFINITIONS = {
     },
     {
         // IIDXCabCamAccess
-        .title = "IIDX Use Official AC Cams",
+        .title = "IIDX Official AC Camera Access",
         .name = "iidxcabcams",
-        .desc = "For IIDX25+, allow direct access to cameras from real arcade cabinets. "
-            "Only turn this on if you have OFFICIAL arcade cameras connected to the correct USB ports. Default: auto.",
+        .desc = "Controls how the game accesses USB cameras for IIDX 25+.\n\n"
+            "auto (default): use [off] when the IIDX module is enabled; otherwise, use [on].\n\n"
+            "on: game discovers and directly accesses cameras; requires official cameras on correct USB ports.\n\n"
+            "legacy: for IIDX 25/26 only; allow camera access with emulated discovery.\n\n"
+            "off: prevent game from accessing USB cameras.",
         .type = OptionType::Enum,
         .game_name = "Beatmania IIDX",
         .category = "Cab Peripherals",
         .elements = {
             {"auto", ""},
+            {"on", ""},
+            {"legacy", ""},
             {"off", ""},
-            {"on", ""}
         },
     },
     {
@@ -977,7 +981,7 @@ static const std::vector<OptionDefinition> OPTION_DEFINITIONS = {
         .display_name = "sdvxsubredraw",
         .aliases= "sdvxsubredraw",
         .desc = "Check if submonitor in fullscreen mode doesn't update every frame; "
-            "this option forces subscreen to redraw every frame.",
+            "this option presents the subscreen when the game does not.",
         .type = OptionType::Bool,
         .game_name = "Sound Voltex",
         .category = "Advanced Game Options",
@@ -1171,7 +1175,7 @@ static const std::vector<OptionDefinition> OPTION_DEFINITIONS = {
         .title = "Pop'n Music PikaPika Subscreen Force Redraw",
         .name = "popnsubredraw",
         .desc = "Check if submonitor in fullscreen mode appears stuck; "
-            "this option forces subscreen to redraw every frame.",
+            "this option presents the subscreen when the game does not.",
         .type = OptionType::Bool,
         .game_name = "Pop'n Music",
         .category = "Advanced Game Options",