Explicitly load the correct FFX API DLL based on the active graphics backend, and use functions dynamically loaded from that library. This allows both DX12 and Vulkan to work properly from the same codebase.

FSR3UnityPlugin.cpp

@@ -14,6 +14,7 @@
 #include "UnityPluginAPI/IUnityGraphicsD3D12.h"
 #include "UnityPluginAPI/IUnityGraphicsVulkan.h"
 
+#include "ffx_api/ffx_api_loader.h"
 #include "ffx_api/ffx_upscale.hpp"
 #include "ffx_api/dx12/ffx_api_dx12.hpp"
 #include "ffx_api/vk/ffx_api_vk.hpp"
@@ -48,6 +49,8 @@ static std::vector<FSR3Feature> s_Features;
 static std::queue<uint32_t> s_FeatureSlots;
 static std::mutex s_FeatureMutex;
 
+static HMODULE s_ffxModule = nullptr;
+static ffxFunctions s_ffxFunctions{};
 static ffx::CreateBackendDX12Desc s_DX12BackendDesc{};
 static ffx::CreateBackendVKDesc s_VulkanBackendDesc{};
 
@@ -156,6 +159,25 @@ static PFN_vkVoidFunction GetVulkanDeviceProcAddr(VkDevice device, const char* p
     return instance.getInstanceProcAddr(instance.instance, pName);
 }
 
+static bool LoadFidelityFXLibrary(_In_ LPCWSTR lpLibFileName)
+{
+    s_ffxModule = LoadLibrary(lpLibFileName);
+    if (s_ffxModule == nullptr)
+    {
+        UNITY_LOG_ERROR(s_Log, "Failed to load FidelityFX library!");
+        return false;
+    }
+
+    ffxLoadFunctions(&s_ffxFunctions, s_ffxModule);
+    if (s_ffxFunctions.CreateContext == nullptr)
+    {
+        UNITY_LOG_ERROR(s_Log, "Failed to load FidelityFX library functions!");
+        return false;
+    }
+
+    return true;
+}
+
 extern "C" bool UNITY_INTERFACE_EXPORT UNITY_INTERFACE_API AMDUP_InitApi()
 {
     if (s_GraphicsD3D12 != nullptr)
@@ -165,7 +187,8 @@ extern "C" bool UNITY_INTERFACE_EXPORT UNITY_INTERFACE_API AMDUP_InitApi()
             return false;
 
         s_DX12BackendDesc.device = device;
-        return true;
+
+        return LoadFidelityFXLibrary(TEXT("amd_fidelityfx_dx12.dll"));
     }
     else if (s_GraphicsVulkan != nullptr)
     {
@@ -176,7 +199,8 @@ extern "C" bool UNITY_INTERFACE_EXPORT UNITY_INTERFACE_API AMDUP_InitApi()
         s_VulkanBackendDesc.vkDevice = instance.device;
         s_VulkanBackendDesc.vkPhysicalDevice = instance.physicalDevice;
         s_VulkanBackendDesc.vkDeviceProcAddr = &GetVulkanDeviceProcAddr;
-        return true;
+        
+        return LoadFidelityFXLibrary(TEXT("amd_fidelityfx_vk.dll"));
     }
 
     return false;
@@ -189,11 +213,17 @@ extern "C" void UNITY_INTERFACE_EXPORT UNITY_INTERFACE_API AMDUP_ShutdownApi()
         auto& feature = s_Features[slot];
         if (feature.upscalingContext != nullptr)
         {
-            ffx::DestroyContext(feature.upscalingContext);
+            s_ffxFunctions.DestroyContext(&feature.upscalingContext, nullptr);
             FreeFeatureSlot(slot);
         }
     }
 
+    if (s_ffxModule != nullptr)
+    {
+        FreeLibrary(s_ffxModule);
+        s_ffxModule = nullptr;
+    }
+    
     s_VulkanBackendDesc.vkDevice = nullptr;
     s_VulkanBackendDesc.vkPhysicalDevice = nullptr;
     s_VulkanBackendDesc.vkDeviceProcAddr = nullptr;
@@ -288,7 +318,7 @@ static void UNITY_INTERFACE_API OnRenderEventAndData(int eventID, void* data)
         auto& feature = s_Features[featureSlot];
         if (feature.upscalingContext != nullptr)
         {
-            ffx::DestroyContext(feature.upscalingContext);
+            s_ffxFunctions.DestroyContext(&feature.upscalingContext, nullptr);
             FreeFeatureSlot(featureSlot);
         }
         break;
@@ -359,7 +389,7 @@ static void UNITY_INTERFACE_API OnRenderEventAndData(int eventID, void* data)
             dispatchUpscale.cameraNear = params->cameraNear;
         }
 
-        ffx::Dispatch(feature.upscalingContext, dispatchUpscale);
+        s_ffxFunctions.Dispatch(&feature.upscalingContext, &dispatchUpscale.header);
         break;
     }
     case BaseEventId + FSR3PluginEvent::ePostExecute:
@@ -385,11 +415,11 @@ static void UNITY_INTERFACE_API OnRenderEventAndData(int eventID, void* data)
 
         if (s_GraphicsD3D12 != nullptr)
         {
-            ffx::CreateContext(feature.upscalingContext, nullptr, createUpscaling, s_DX12BackendDesc);
+            s_ffxFunctions.CreateContext(&feature.upscalingContext, ffx::LinkHeaders(createUpscaling.header, s_DX12BackendDesc.header), nullptr);
         }
         else if (s_GraphicsVulkan != nullptr)
         {
-            ffx::CreateContext(feature.upscalingContext, nullptr, createUpscaling, s_VulkanBackendDesc);
+            s_ffxFunctions.CreateContext(&feature.upscalingContext, ffx::LinkHeaders(createUpscaling.header, s_VulkanBackendDesc.header), nullptr);
         }
         break;
     }

FSR3UnityPlugin.vcxproj

@@ -124,7 +124,7 @@
       <SubSystem>Windows</SubSystem>
       <GenerateDebugInformation>true</GenerateDebugInformation>
       <EnableUAC>false</EnableUAC>
-      <AdditionalDependencies>$(CoreLibraryDependencies);%(AdditionalDependencies);lib\amd_fidelityfx_dx12.lib;lib\amd_fidelityfx_vk.lib;vulkan-1.lib</AdditionalDependencies>
+      <AdditionalDependencies>$(CoreLibraryDependencies);%(AdditionalDependencies);vulkan-1.lib</AdditionalDependencies>
       <AdditionalLibraryDirectories>%VULKAN_SDK%\Lib;%(AdditionalLibraryDirectories)</AdditionalLibraryDirectories>
     </Link>
   </ItemDefinitionGroup>
@@ -146,7 +146,7 @@
       <OptimizeReferences>true</OptimizeReferences>
       <GenerateDebugInformation>true</GenerateDebugInformation>
       <EnableUAC>false</EnableUAC>
-      <AdditionalDependencies>$(CoreLibraryDependencies);%(AdditionalDependencies);lib\amd_fidelityfx_dx12.lib;lib\amd_fidelityfx_vk.lib;vulkan-1.lib</AdditionalDependencies>
+      <AdditionalDependencies>$(CoreLibraryDependencies);%(AdditionalDependencies);vulkan-1.lib</AdditionalDependencies>
       <AdditionalLibraryDirectories>%VULKAN_SDK%\Lib;%(AdditionalLibraryDirectories)</AdditionalLibraryDirectories>
     </Link>
   </ItemDefinitionGroup>