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/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/launcher/options.cpp

@@ -981,7 +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",
@@ -1175,7 +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",