add SetupMetaXRAvailability during the build time to define WITH_METAXR

Source/SenseGloveTracking/SenseGloveTracking.Build.cs

@@ -33,7 +33,9 @@
  */
 
 
+using EpicGames.Core;
 using System;
+using System.Diagnostics;
 using System.IO;
 using UnrealBuildTool;
 
@@ -104,5 +106,87 @@ public class SenseGloveTracking : ModuleRules
         );
 
         AddEngineThirdPartyPrivateStaticDependencies(Target, "OpenXR");
+
+        SetupMetaXRAvailability(Target);
+    }
+
+       private string FindPluginPath(string PluginName)
+       {
+           string[] PossiblePluginDirs = new string[]
+           {
+               Path.Combine(EngineDirectory, "Plugins"),
+               Path.Combine(EngineDirectory, "Plugins", "Marketplace"),
+               Path.Combine(ModuleDirectory, "..", "..", "..", "..", "Plugins"),
+           };
+
+           foreach (string BaseDir in PossiblePluginDirs)
+           {
+               string PluginDir = Path.Combine(BaseDir, PluginName);
+               if (Directory.Exists(PluginDir))
+               {
+                   return PluginDir;
+               }
+           }
+
+           return string.Empty;
+       }
+
+    private void SetupMetaXRAvailability(ReadOnlyTargetRules Target)
+    {
+        const string MetaXRFriendlyName = "MetaXR";
+        const string MetaXRPluginName = "OculusXR";
+
+        PublicDefinitions.Add("WITH_METAXR=0");
+
+        if (JsonObject.TryRead(Target.ProjectFile, out var UProjectRawObject))
+        {
+            if (UProjectRawObject.TryGetObjectArrayField("Plugins", out var PluginsObject))
+            {
+                foreach (JsonObject PluginObject in PluginsObject)
+                {
+                    PluginObject.TryGetStringField("Name", out var PluginName);
+                    PluginObject.TryGetBoolField("Enabled", out var PluginEnabled);
+
+                    if (PluginName == MetaXRPluginName && PluginEnabled)
+                    {
+                        string MetaXRDir = Path.GetFullPath(FindPluginPath(MetaXRFriendlyName));
+                        if (MetaXRDir == string.Empty)
+                        {
+                            Debug.Assert(false, "Cannot find the MetaXRDir!");
+                        }
+
+                        string MetaXRSourceDir = Path.Combine(MetaXRDir, "Source");
+                        string OculusXRHMDDir = Path.Combine(MetaXRSourceDir, "OculusXRInput");
+                        string OculusXRHMDPrivateIncludeDir = Path.Combine(OculusXRHMDDir, "Private");
+                        string OculusXRInputDir = Path.Combine(MetaXRSourceDir, "OculusXRHMD");
+                        string OculusXRInputPrivateIncludeDir = Path.Combine(OculusXRInputDir, "Private");
+
+                        string MetaXRThirdPartyDir = Path.Combine(MetaXRSourceDir, "ThirdParty");
+                        string OVRPluginIncludeDir =
+                            Path.Combine(MetaXRThirdPartyDir, "OVRPlugin", "OVRPlugin", "Include");
+
+                        PrivateIncludePaths.AddRange(
+                            new string[]
+                            {
+                                OculusXRHMDPrivateIncludeDir,
+                                OculusXRInputPrivateIncludeDir,
+                                OVRPluginIncludeDir,
+                            }
+                        );
+
+                        PrivateIncludePathModuleNames.AddRange(
+                            new string[]
+                            {
+                                "OculusXRHMD",
+                                "OculusXRInput",
+                            }
+                        );
+
+                        PublicDefinitions.Remove("WITH_METAXR=0");
+                        PublicDefinitions.Add("WITH_METAXR=1");
+                    }
+                }
+            }
+        }
     }
 }