Joints: Difference between revisions

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== Automatic creation ==
== Automatic creation ==
<!-- mention how they're automatically created here -->


== How joints work ==


== Advanced ==
=== Fixed Joints ===
Joints have a conceptual origin coordinate frame, to which both parts are attached.


jointOrigin == joint.Part0.CFrame * joint.C0 == joint.Part1.CFrame * joint.C1


In the case of fixed joints, this origin position is not important. <!--Or do explosions only act on joint origins? -->


  weld.Part1.CFrame == weld.Part0.CFrame * weld.C0 * weld.C1:inverse()
It is sufficient to make the origin position the center of Part1, and C1 the identity CFrame. For example:
 
local cf = ... --The transformation from A to B
   
local weld = Instance.new("Weld")
      weld.Part0 = workspace.A
      weld.Part1 = workspace.B
      weld.C0 = cf
      weld.C1 = CFrame.new(0,0,0)
 
Will ensure that workspace.A * cf == workspace.B
 
=== Rotating Joints ===
 
In a rotating joint, the conceptual origin is important. This dictates the position, and in some cases, the axis around which the joint rotates.
 
<!-- Which axis does it rotate around? jointOrigin * Vector3.new(1,0,0), jointOrigin * Vector3.new(0,1,0), or jointOrigin * Vector3.new(0,0,1)? -->

Revision as of 17:18, 15 January 2012

A joint, called a "connection" while a game is loading, is something that connects two parts together. Common types of joints are Welds, Snaps, and Hinges. Joints are represented using a JointInstance object, which has four important properties: C0, C1, Part0, and Part1.

Automatic creation

Advanced

Fixed Joints

Joints have a conceptual origin coordinate frame, to which both parts are attached.

jointOrigin == joint.Part0.CFrame * joint.C0 == joint.Part1.CFrame * joint.C1

In the case of fixed joints, this origin position is not important.

It is sufficient to make the origin position the center of Part1, and C1 the identity CFrame. For example:

local cf = ... --The transformation from A to B

local weld = Instance.new("Weld")
      weld.Part0 = workspace.A
      weld.Part1 = workspace.B
      weld.C0 = cf
      weld.C1 = CFrame.new(0,0,0)

Will ensure that workspace.A * cf == workspace.B

Rotating Joints

In a rotating joint, the conceptual origin is important. This dictates the position, and in some cases, the axis around which the joint rotates.