editor: error on d3d12

Assets/VLCUnity/Editor/PreBuild.cs

@@ -26,6 +26,10 @@ public class PreProcessBuild :
         "\n\nPlease go to Player Settings > Android > Auto Graphics API and remove Vulkan from the list." +
         "\nOnly OpenGL ES 2.0 and 3.0 are currently supported on Android.";
 
+        const string WindowsD3D12ErrorMessage = "The Direct3D12 graphics API is not supported by the VLC Unity plugin." +
+        "\n\nPlease go to Player Settings > Windows or UWP > Auto Graphics API and remove Direct3D12 from the list." +
+        "\nOnly Direct3D11 is currently supported on Windows and UWP targets.";
+
 #if UNITY_SUPPORTS_BUILD_REPORT
         public void OnPreprocessBuild(BuildReport report)
         {
@@ -42,10 +46,19 @@ public void OnPreprocessBuild(BuildTarget target, string path)
                     throw new BuildFailedException(AndroidVulkanErrorMessage);
                 }
             }
+            else if(target == BuildTarget.StandaloneWindows64 || target == BuildTarget.WSAPlayer)
+            {
+                if(IsD3D12Configured(target))
+                {
+                    throw new BuildFailedException(WindowsD3D12ErrorMessage);
+                }
+            }
         }
 
         static bool IsVulkanConfigured => GetGraphicsApiIndex(BuildTarget.Android, GraphicsDeviceType.Vulkan) >= 0;
 
+        static bool IsD3D12Configured(BuildTarget target) => GetGraphicsApiIndex(target, GraphicsDeviceType.Direct3D12) >= 0;
+
         static int GetGraphicsApiIndex(BuildTarget target, GraphicsDeviceType api)
         {
             int result = -1;