IsPointerEqual (ACS and Decorate)

Decorate: IsPointerEqual(int aaptr_selector1, int aaptr_selector2)
ACS: IsPointerEqual(int aaptr_selector1, int aaptr_selector2, int tid1 = 0, int tid2 = 0)

Compare the pointers values returned by two pointer select operations. Returns true if they both resolve to the same value. Null values can be explicitly tested using IsPointerEqual(AAPTR_NULL, ...)

ACS: IsPointerEqual(int aaptr1, int aaptr2, int tid1 = 0, int tid2 = 0)

This function lets you compare pointers from other actors than the activator, using tids. Tid1 determines the actor used to resolve aaptr1, Tid2 does the same for aaptr2. If tid1 and tid2 are equal, the same actor will be used for resolving both pointers (that could always happen randomly; this way you know it will happen).

src/namedef.h

@@ -299,6 +299,7 @@ xx(ACS_NamedExecuteWithResult)
 xx(CallACS)
 xx(Sqrt)
 xx(CheckClass)
+xx(IsPointerEqual)
 
 // Various actor names which are used internally
 xx(MapSpot)

src/p_acs.cpp

@@ -4373,6 +4373,7 @@ enum EACSFunctions
 	ACSF_GetArmorInfo,
 	ACSF_DropInventory,
 	ACSF_PickActor,
+	ACSF_IsPointerEqual,
 
 	/* Zandronum's - these must be skipped when we reach 99!
 	-100:ResetMap(0),
@@ -5630,6 +5631,22 @@ doplaysound:			if (funcIndex == ACSF_PlayActorSound)
 			}
 			break;
 
+		case ACSF_IsPointerEqual:
+			{
+				int tid1 = 0, tid2 = 0;
+				switch (argCount)
+				{
+				case 4: tid2 = args[3];
+				case 3: tid1 = args[2];
+				}
+
+				actor = SingleActorFromTID(tid1, activator);
+				AActor * actor2 = tid2 == tid1 ? actor : SingleActorFromTID(tid2, activator);
+
+				return COPY_AAPTR(actor, args[0]) == COPY_AAPTR(actor2, args[1]);
+			}
+			break;
+
 		default:
 			break;
 	}

src/thingdef/thingdef_function.cpp

@@ -260,4 +260,37 @@ class FxGlobalFunctionCall_CheckClass : public FxGlobalFunctionCall
 		}
 	};
 
-GLOBALFUNCTION_ADDER(CheckClass);
+GLOBALFUNCTION_ADDER(CheckClass);
+
+//==========================================================================
+//
+// Function: ispointerequal
+//
+//==========================================================================
+
+class FxGlobalFunctionCall_IsPointerEqual : public FxGlobalFunctionCall
+{
+	public:
+		GLOBALFUNCTION_DEFINE(IsPointerEqual);
+		
+		FxExpression *Resolve(FCompileContext& ctx)
+		{
+			CHECKRESOLVED();
+			
+			if (!ResolveArgs(ctx, 2, 2, true))
+				return NULL;
+			
+			ValueType = VAL_Int;
+			return this;
+		}
+		
+		ExpVal EvalExpression(AActor *self)
+		{
+			ExpVal ret;
+			ret.Type = VAL_Int;
+			ret.Int = COPY_AAPTR(self, (*ArgList)[0]->EvalExpression(self).GetInt()) == COPY_AAPTR(self, (*ArgList)[1]->EvalExpression(self).GetInt());
+			return ret;
+		}
+};
+
+GLOBALFUNCTION_ADDER(IsPointerEqual);