From 5e6b6133ca4d046f7513d57af00f7beeca54d049 Mon Sep 17 00:00:00 2001
From: Wojtek Figat <wojtek@figat.pl>
Date: Wed, 27 Oct 2021 20:37:46 +0200
Subject: [PATCH] Add `Joint.SetJointLocation` for easier joints setup

---
 Source/Engine/Physics/Joints/Joint.cpp | 12 ++++++++++++
 Source/Engine/Physics/Joints/Joint.h   | 11 +++++++----
 2 files changed, 19 insertions(+), 4 deletions(-)

diff --git a/Source/Engine/Physics/Joints/Joint.cpp b/Source/Engine/Physics/Joints/Joint.cpp
index d688041ff..f9808efc6 100644
--- a/Source/Engine/Physics/Joints/Joint.cpp
+++ b/Source/Engine/Physics/Joints/Joint.cpp
@@ -89,6 +89,18 @@ void Joint::SetTargetAnchorRotation(const Quaternion& value)
     }
 }
 
+void Joint::SetJointLocation(const Vector3& location)
+{
+    if (GetParent())
+    {
+        SetLocalPosition(GetParent()->GetTransform().WorldToLocal(location));
+    }
+    if (Target)
+    {
+        SetTargetAnchor(Target->GetTransform().WorldToLocal(location));
+    }
+}
+
 void Joint::GetCurrentForce(Vector3& linear, Vector3& angular) const
 {
     if (_joint && _joint->getConstraint())
diff --git a/Source/Engine/Physics/Joints/Joint.h b/Source/Engine/Physics/Joints/Joint.h
index f2950874f..95d33c421 100644
--- a/Source/Engine/Physics/Joints/Joint.h
+++ b/Source/Engine/Physics/Joints/Joint.h
@@ -36,8 +36,6 @@ public:
     API_FIELD(Attributes="EditorOrder(0), DefaultValue(null), EditorDisplay(\"Joint\")")
     ScriptingObjectReference<Actor> Target;
 
-public:
-
     /// <summary>
     /// Gets the break force. Determines the maximum force the joint can apply before breaking. Broken joints no longer participate in physics simulation.
     /// </summary>
@@ -130,6 +128,13 @@ public:
         return _joint;
     }
 
+    /// <summary>
+    /// Sets the location of the joint by automatically computing local position and target anchor to place a joint at the given location (world-space).
+    /// </summary>
+    /// <remarks>Use this utility to automatically place joint at the given location after setting up joint parent and target.</remarks>
+    /// <param name="location">The joint location to set (world-space).</param>
+    API_FUNCTION() void SetJointLocation(const Vector3& location);
+
     /// <summary>
     /// Gets the current force applied by the solver to maintain all constraints.
     /// </summary>
@@ -142,8 +147,6 @@ public:
     /// </summary>
     void Create();
 
-public:
-
     /// <summary>
     /// Occurs when a joint gets broken during simulation.
     /// </summary>