From c3c1e76e8a28f01b1d6e48daced80b546c34499e Mon Sep 17 00:00:00 2001
From: Major Cooke <paul.growney22@gmail.com>
Date: Sun, 31 Dec 2017 19:02:14 -0600
Subject: [PATCH] Added vector diff functions to ZScript LevelLocals class
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Vec2Diff() and Vec3Diff() work like Actor’s Vec2To() and Vec3To() but use arbitrary points
---
 src/g_level.cpp                | 46 ++++++++++++++++++++++++++++++++++
 wadsrc/static/zscript/base.txt |  3 +++
 2 files changed, 49 insertions(+)

diff --git a/src/g_level.cpp b/src/g_level.cpp
index cb5bc4baf..ce8ff0850 100644
--- a/src/g_level.cpp
+++ b/src/g_level.cpp
@@ -1954,6 +1954,52 @@ DEFINE_ACTION_FUNCTION(FLevelLocals, SetInterMusic)
 	return 0;
 }
 
+//==========================================================================
+//
+//
+//==========================================================================
+
+template <typename T>
+inline T VecDiff(const T& v1, const T& v2)
+{
+	T result = v2 - v1;
+
+	if (level.subsectors.Size() > 0)
+	{
+		const sector_t *const sec1 = P_PointInSector(v1);
+		const sector_t *const sec2 = P_PointInSector(v2);
+
+		if (nullptr != sec1 && nullptr != sec2)
+		{
+			result += Displacements.getOffset(sec2->PortalGroup, sec1->PortalGroup);
+		}
+	}
+
+	return result;
+}
+
+DEFINE_ACTION_FUNCTION(FLevelLocals, Vec2Diff)
+{
+	PARAM_PROLOGUE;
+	PARAM_FLOAT(x1);
+	PARAM_FLOAT(y1);
+	PARAM_FLOAT(x2);
+	PARAM_FLOAT(y2);
+	ACTION_RETURN_VEC2(VecDiff(DVector2(x1, y1), DVector2(x2, y2)));
+}
+
+DEFINE_ACTION_FUNCTION(FLevelLocals, Vec3Diff)
+{
+	PARAM_PROLOGUE;
+	PARAM_FLOAT(x1);
+	PARAM_FLOAT(y1);
+	PARAM_FLOAT(z1);
+	PARAM_FLOAT(x2);
+	PARAM_FLOAT(y2);
+	PARAM_FLOAT(z2);
+	ACTION_RETURN_VEC3(VecDiff(DVector3(x1, y1, z1), DVector3(x2, y2, z2)));
+}
+
 //==========================================================================
 //
 //
diff --git a/wadsrc/static/zscript/base.txt b/wadsrc/static/zscript/base.txt
index 4ffe34dce..01e2af795 100644
--- a/wadsrc/static/zscript/base.txt
+++ b/wadsrc/static/zscript/base.txt
@@ -552,6 +552,9 @@ struct LevelLocals native
 	native bool IsJumpingAllowed() const;
 	native bool IsCrouchingAllowed() const;
 	native bool IsFreelookAllowed() const;
+
+	native static clearscope vector2 Vec2Diff(vector2 v1, vector2 v2);
+	native static clearscope vector3 Vec3Diff(vector3 v1, vector3 v2);
 	
 	String TimeFormatted(bool totals = false)
 	{