From df6e2ac98dbaafa98fee66ee118e1b1e41b35662 Mon Sep 17 00:00:00 2001
From: maelstrom <maelstrom@maelstrom.dev>
Date: Wed, 30 Apr 2025 17:20:04 +0200
Subject: [PATCH] fix(part): hinge joint only made if other part intersects the
 hinge

---
 core/src/objects/joint/rotate.cpp | 2 +-
 core/src/objects/part.cpp         | 8 +++++---
 core/src/objects/part.h           | 2 +-
 3 files changed, 7 insertions(+), 5 deletions(-)

diff --git a/core/src/objects/joint/rotate.cpp b/core/src/objects/joint/rotate.cpp
index 10b7ce3..c0c5c89 100644
--- a/core/src/objects/joint/rotate.cpp
+++ b/core/src/objects/joint/rotate.cpp
@@ -28,7 +28,7 @@ void Rotate::buildJoint() {
     part1.lock()->cframe = newFrame;
     workspace->SyncPartPhysics(part1.lock());
     // Do NOT use Abs() in this scenario. For some reason that breaks it
-    rp::HingeJointInfo jointInfo(part0.lock()->rigidBody, part1.lock()->rigidBody, newFrame.Position(), -(part0.lock()->cframe * c0).LookVector().Unit());
+    rp::HingeJointInfo jointInfo(part0.lock()->rigidBody, part1.lock()->rigidBody, (part0.lock()->cframe * c0).Position(), -(part0.lock()->cframe * c0).LookVector().Unit());
     this->joint = dynamic_cast<rp::HingeJoint*>(workspace->physicsWorld->createJoint(jointInfo));
     jointWorkspace = workspace;
 
diff --git a/core/src/objects/part.cpp b/core/src/objects/part.cpp
index 3c952a4..21538d6 100644
--- a/core/src/objects/part.cpp
+++ b/core/src/objects/part.cpp
@@ -183,8 +183,7 @@ bool Part::checkJointContinuityUp(std::shared_ptr<Part> otherPart) {
     return true;
 }
 
-bool Part::checkSurfacesTouching(CFrame surfaceFrame, Vector3 myFace, Vector3 otherFace, std::shared_ptr<Part> otherPart) {
-    // Vector3 otherPartCenterToMine = surfaceFrame.Inverse() * otherPart->cframe.Position();
+bool Part::checkSurfacesTouching(CFrame surfaceFrame, Vector3 size, Vector3 myFace, Vector3 otherFace, std::shared_ptr<Part> otherPart) {
     Vector3 farCorner0 = surfaceFrame.Inverse() * otherPart->cframe * (Vector3::ONE * (otherPart->size / 2.f));
     Vector3 farCorner1 = surfaceFrame.Inverse() * otherPart->cframe * (-Vector3::ONE * (otherPart->size / 2.f));
     
@@ -251,12 +250,15 @@ void Part::MakeJoints() {
                 if (dot > -0.99) continue; // Surface is pointing opposite to ours
 
                 if (abs(surfacePointLocalToMyFrame.Z()) > 0.05) continue; // Surfaces are within 0.05 studs of one another
-                if (!checkSurfacesTouching(surfaceFrame, myFace, otherFace, otherPart)) continue; // Surface do not overlap
+                if (!checkSurfacesTouching(surfaceFrame, size, myFace, otherFace, otherPart)) continue; // Surface do not overlap
                 if (!checkJointContinuity(otherPart)) continue;
 
                 SurfaceType mySurface = surfaceFromFace(faceFromNormal(myFace));
                 SurfaceType otherSurface = surfaceFromFace(faceFromNormal(otherFace));
 
+                // If it is a hinge, only attach if actually touching the "hinge"
+                if (mySurface == SurfaceHinge && !checkSurfacesTouching(surfaceFrame, Vector3(0.4, 0.4, 0.4), myFace, otherFace, otherPart)) continue;
+
                 // Create contacts
                 // Contact always occurs at the center of Part0's surface (even if that point does not overlap both surfaces)
                 // Contact 0 is Part0's contact relative to Part0. It should point *opposite* the direction of its surface normal
diff --git a/core/src/objects/part.h b/core/src/objects/part.h
index e885033..cd7bf3c 100644
--- a/core/src/objects/part.h
+++ b/core/src/objects/part.h
@@ -43,7 +43,7 @@ protected:
     bool checkJointContinuity(std::shared_ptr<Part>);
     bool checkJointContinuityUp(std::shared_ptr<Part>);
     bool checkJointContinuityDown(std::shared_ptr<Part>);
-    bool checkSurfacesTouching(CFrame surfaceFrame, Vector3 myFace, Vector3 otherFace, std::shared_ptr<Part> otherPart); 
+    bool checkSurfacesTouching(CFrame surfaceFrame, Vector3 size, Vector3 myFace, Vector3 otherFace, std::shared_ptr<Part> otherPart); 
 
     friend JointInstance;