VR Lua interface (scp-fs2open#5858)

* Allow lua to check whether VR is enabled

* Add global hook condition

* Add missing descriptionm

Author: BMagnu

code/scripting/api/libs/graphics.cpp

@@ -23,6 +23,7 @@
 #include <freespace.h>
 #include <globalincs/systemvars.h>
 #include <graphics/2d.h>
+#include <graphics/openxr.h>
 #include <graphics/material.h>
 #include <graphics/matrix.h>
 #include <hud/hudbrackets.h>
@@ -2269,5 +2270,10 @@ ADE_FUNC(createColor,
 	return ade_set_args(L, "o", l_Color.Set(thisColor));
 }
 
+ADE_FUNC(isVR, l_Graphics, nullptr, "Queries whether or not FSO is currently trying to render to a head-mounted VR display.", "boolean", "true if FSO is currently outputting frames to a VR headset.")
+{
+	return ade_set_args(L, "b", openxr_enabled());
+}
+
 } // namespace api
 } // namespace scripting

code/scripting/scripting.cpp

@@ -11,6 +11,7 @@
 #include "bmpman/bmpman.h"
 #include "controlconfig/controlsconfig.h"
 #include "gamesequence/gamesequence.h"
+#include "graphics/openxr.h"
 #include "hud/hud.h"
 #include "io/key.h"
 #include "mission/missioncampaign.h"
@@ -41,6 +42,7 @@ flag_def_list Script_conditions[] =
 	{"Version", CHC_VERSION, 0},
 	{"Application", CHC_APPLICATION, 0},
 	{"Multi type", CHC_MULTI_SERVER, 0},
+	{"VR device", CHC_VR_MODE, 0}
 };
 
 int Num_script_conditions = sizeof(Script_conditions) / sizeof(flag_def_list);
@@ -263,6 +265,10 @@ static bool global_condition_valid(const script_condition& condition)
 		return static_cast<bool>(condition.condition_cached_value == 1) == static_cast<bool>(MULTIPLAYER_MASTER);
 	}
 
+	case CHC_VR_MODE: {
+		return static_cast<bool>(condition.condition_cached_value == 1) == openxr_enabled();
+	}
+
 	default:
 		break;
 	}
@@ -310,6 +316,17 @@ int cache_condition(ConditionalType type, const SCP_string& value){
 			return 0;
 		}
 	}
+	case CHC_VR_MODE:
+	{
+		if (stricmp("VR", value.c_str()) == 0 || stricmp("HMD", value.c_str()) == 0 || stricmp("enabled", value.c_str()) == 0)
+		{
+			return 1;
+		}
+		else
+		{
+			return 0;
+		}
+	}
 	default:
 		return -1;
 	}

code/scripting/scripting.h

@@ -62,7 +62,8 @@ enum ConditionalType {
 	CHC_KEYPRESS,    
 	CHC_VERSION,    
 	CHC_APPLICATION, 
-	CHC_MULTI_SERVER
+	CHC_MULTI_SERVER,
+	CHC_VR_MODE
 };
 
 //Actions