Add AMD FSR2 SDK detection and backend integration scaffolding

CMakeLists.txt

@@ -22,6 +22,25 @@ set(CMAKE_ARCHIVE_OUTPUT_DIRECTORY ${CMAKE_BINARY_DIR}/lib)
 option(BUILD_SHARED_LIBS "Build shared libraries" OFF)
 option(WOWEE_BUILD_TESTS "Build tests" OFF)
 option(WOWEE_ENABLE_ASAN "Enable AddressSanitizer (Debug builds)" OFF)
+option(WOWEE_ENABLE_AMD_FSR2 "Enable AMD FidelityFX FSR2 backend when SDK is present" ON)
+
+# AMD FidelityFX FSR2 SDK detection (drop-in under extern/FidelityFX-FSR2)
+set(WOWEE_AMD_FSR2_DIR ${CMAKE_SOURCE_DIR}/extern/FidelityFX-FSR2)
+set(WOWEE_AMD_FSR2_HEADER ${WOWEE_AMD_FSR2_DIR}/src/ffx-fsr2-api/ffx_fsr2.h)
+if(WOWEE_ENABLE_AMD_FSR2 AND EXISTS ${WOWEE_AMD_FSR2_HEADER})
+    message(STATUS "AMD FSR2 SDK detected at ${WOWEE_AMD_FSR2_DIR}")
+    add_compile_definitions(WOWEE_HAS_AMD_FSR2=1)
+    include_directories(
+        ${WOWEE_AMD_FSR2_DIR}/src
+        ${WOWEE_AMD_FSR2_DIR}/src/ffx-fsr2-api
+        ${WOWEE_AMD_FSR2_DIR}/src/ffx-fsr2-api/vk
+    )
+else()
+    add_compile_definitions(WOWEE_HAS_AMD_FSR2=0)
+    if(WOWEE_ENABLE_AMD_FSR2)
+        message(WARNING "AMD FSR2 SDK not found at ${WOWEE_AMD_FSR2_DIR}; using internal fallback implementation.")
+    endif()
+endif()
 
 # Opcode registry generation/validation
 find_package(Python3 COMPONENTS Interpreter QUIET)

docs/AMD_FSR2_INTEGRATION.md

@@ -0,0 +1,50 @@
+# AMD FSR2 Integration Notes
+
+This project currently has two FSR2 states:
+
+- `AMD FidelityFX SDK` backend (preferred): enabled when SDK sources are present.
+- `Internal fallback` backend: used when SDK is missing.
+
+## SDK Location
+
+Drop AMD's official FSR2 repo at:
+
+`extern/FidelityFX-FSR2`
+
+Expected header for detection:
+
+`extern/FidelityFX-FSR2/src/ffx-fsr2-api/ffx_fsr2.h`
+
+## Build Flags
+
+- `WOWEE_ENABLE_AMD_FSR2=ON` (default): try to use AMD SDK if detected.
+- `WOWEE_HAS_AMD_FSR2` compile define:
+  - `1` when SDK header is found.
+  - `0` otherwise (fallback path).
+
+## Current Status
+
+- CMake detects the SDK and defines `WOWEE_HAS_AMD_FSR2`.
+- UI shows active FSR2 backend label in settings.
+- Runtime logs clearly indicate whether AMD SDK is available.
+
+## Remaining Work (to finish official AMD path)
+
+1. Add backend wrapper around `FfxFsr2Context` and Vulkan backend helpers.
+2. Feed required inputs each frame:
+   - Color, depth, motion vectors
+   - Jitter offsets
+   - Delta time and render/display resolution
+   - Exposure / reactive mask as needed
+3. Replace custom compute accumulation path with `ffxFsr2ContextDispatch`.
+4. Keep current fallback path behind a runtime switch for safety.
+5. Add a debug overlay:
+   - Backend in use
+   - Internal resolution
+   - Jitter values
+   - Motion vector validity stats
+6. Validate with fixed camera + movement sweeps:
+   - Static shimmer
+   - Moving blur/ghosting
+   - Fine geometry stability
+

include/rendering/renderer.hpp

@@ -270,6 +270,11 @@ public:
     float getFSRSharpness() const { return fsr_.sharpness; }
     void setFSR2Enabled(bool enabled);
     bool isFSR2Enabled() const { return fsr2_.enabled; }
+#if WOWEE_HAS_AMD_FSR2
+    bool isAmdFsr2SdkAvailable() const { return true; }
+#else
+    bool isAmdFsr2SdkAvailable() const { return false; }
+#endif
 
     void setWaterRefractionEnabled(bool enabled);
     bool isWaterRefractionEnabled() const;

src/rendering/renderer.cpp

@@ -3739,6 +3739,11 @@ bool Renderer::initFSR2Resources() {
     LOG_INFO("FSR2: initializing at ", fsr2_.internalWidth, "x", fsr2_.internalHeight,
              " -> ", swapExtent.width, "x", swapExtent.height,
              " (scale=", fsr2_.scaleFactor, ")");
+#if WOWEE_HAS_AMD_FSR2
+    LOG_INFO("FSR2: AMD FidelityFX SDK detected at build time.");
+#else
+    LOG_WARNING("FSR2: AMD FidelityFX SDK not detected; using internal fallback path.");
+#endif
 
     VkFormat colorFmt = vkCtx->getSwapchainFormat();
     VkFormat depthFmt = vkCtx->getDepthFormat();

src/ui/game_screen.cpp

@@ -6311,6 +6311,10 @@ void GameScreen::renderSettingsWindow() {
                         saveSettings();
                     }
                     if (fsrMode > 0) {
+                        if (fsrMode == 2 && renderer) {
+                            ImGui::TextDisabled("FSR2 backend: %s",
+                                renderer->isAmdFsr2SdkAvailable() ? "AMD FidelityFX SDK" : "Internal fallback");
+                        }
                         const char* fsrQualityLabels[] = { "Ultra Quality (77%)", "Quality (67%)", "Balanced (59%)", "Performance (50%)" };
                         static const float fsrScaleFactors[] = { 0.77f, 0.67f, 0.59f, 0.50f };
                         if (ImGui::Combo("FSR Quality", &pendingFSRQuality, fsrQualityLabels, 4)) {