Make mobility links into objects, also fix to obscure gearbox bug

What it says on the tin, making a step into a mobility rewrite more accessible
As of right now they still function the same as before, but they are more centralized and at least a little bit easier to understand; these have accessor functions to modify certain parts of the links as well as obtain them
Eventually it might be a good idea to solely use these to transfer torque throughout the drivetrain as opposed to doing it per gearbox, and these have debugoverlay drawings to represent that transfer

Also a sort of bandaid fix for a bigger issue when it comes to splitting power from an engine to multiple gearboxes, only to then rejoin them afterwards to one wheel

lua/acf/mobility/objects_sv/link.lua

@@ -0,0 +1,47 @@
+local ACF	= ACF
+local Meta	= {}
+local String	= "Link [Source = %s, Target = %s, Origin = %s, Axis = %s]"
+local Debug		= ACF.Debug
+local Objects	= ACF.Mobility.Objects
+
+function Objects.Link(Source, Target)
+	local Link	= {
+		Vel		= 0,
+		ReqTq	= 0,
+
+		Source	= Source,
+		Target	= Target,
+		Origin		= Vector(),
+		TargetPos	= Vector(),
+		Axis 		= Vector(1, 0, 0),
+		IsGearbox	= Target.IsACFGearbox or false
+	}
+
+	setmetatable(Link, Meta)
+
+	return Link
+end
+
+local red		= Color(255, 0, 0)
+local orange	= Color(255, 127, 0)
+function Meta:Transfer( Torque )
+	local P1 = self.Source:LocalToWorld(self.Origin)
+	local P2 = self.Target:LocalToWorld(self.TargetPos)
+	Debug.Line(P1, P2, 0.05, self.IsGearbox and red or orange, true)
+	Debug.Text(LerpVector(0.5, P1, P2), math.Round(Torque, 1) .. " Nm", 0.05, false)
+
+
+end
+
+function Meta:ToString()
+	return String:format(self.Source, self.Target, self.Origin, self.Axis)
+end
+
+AccessorFunc(Meta, "Source", "Source")
+AccessorFunc(Meta, "Target", "Target")
+AccessorFunc(Meta, "Origin", "Origin", FORCE_VECTOR)
+AccessorFunc(Meta, "Axis", "Axis", FORCE_VECTOR)
+AccessorFunc(Meta, "TargetPos", "TargetPos", FORCE_VECTOR)
+
+Meta.__index	= Meta
+Meta.__tostring	= Meta.ToString

lua/entities/acf_engine/init.lua

@@ -4,6 +4,8 @@ AddCSLuaFile("shared.lua")
 include("shared.lua")
 
 local ACF = ACF
+local Mobility	  = ACF.Mobility
+local MobilityObj = Mobility.Objects
 local MaxDistance = ACF.LinkDistance * ACF.LinkDistance
 
 --===============================================================================================--
@@ -69,11 +71,14 @@ do
 			Rope = constraint.CreateKeyframeRope(OutPos, 1, "cable/cable2", nil, Engine, Engine.Out, 0, Target, Target.In, 0)
 		end
 
-		local Link = {
-			Rope = Rope,
-			RopeLen = (OutPos - InPos):Length(),
-			ReqTq = 0
-		}
+		local Link = MobilityObj.Link(Engine, Target)
+
+		Link:SetOrigin(Engine.Out)
+		Link:SetTargetPos(Target.In)
+		Link:SetAxis(Direction)
+
+		Link.Rope	= Rope
+		Link.RopeLen	= (OutPos - InPos):Length()
 
 		Engine.Gearboxes[Target] = Link
 		Target.Engines[Engine]	 = true
@@ -781,6 +786,7 @@ function ENT:CalcRPM(SelfTbl)
 
 		-- Split the torque fairly between the gearboxes who need it
 		for Ent, Link in pairs(BoxesTbl) do
+			Link:Transfer(Link.ReqTq * AvailRatio * MassRatio)
 			Ent:Act(Link.ReqTq * AvailRatio * MassRatio, DeltaTime, MassRatio)
 		end
 	end

lua/entities/acf_gearbox/init.lua

@@ -9,11 +9,14 @@ include("shared.lua")
 
 local ACF         = ACF
 local Contraption = ACF.Contraption
+local Mobility	  = ACF.Mobility
+local MobilityObj = Mobility.Objects
 local Utilities   = ACF.Utilities
 local Clock       = Utilities.Clock
 local Clamp       = math.Clamp
 local abs         = math.abs
 local min         = math.min
+local max         = math.max
 local HookRun     = hook.Run
 local MaxDistance = ACF.LinkDistance * ACF.LinkDistance
 
@@ -158,7 +161,7 @@ do -- Spawn and Update functions -----------------------
 		if not next(Ropes) then return end
 
 		for Ent, Link in pairs(Ropes) do
-			local OutPos = Entity:LocalToWorld(Link.Output)
+			local OutPos = Entity:LocalToWorld(Link:GetOrigin())
 			local InPos = Ent.In and Ent:LocalToWorld(Ent.In) or Ent:GetPos()
 
 			-- make sure it is not stretched too far
@@ -168,7 +171,7 @@ do -- Spawn and Update functions -----------------------
 			end
 
 			-- make sure the angle is not excessive
-			local DrvAngle = (OutPos - InPos):GetNormalized():Dot((Entity:GetRight() * Link.Output.y):GetNormalized())
+			local DrvAngle = (OutPos - InPos):GetNormalized():Dot((Entity:GetRight() * Link:GetOrigin().y):GetNormalized())
 
 			if DrvAngle < 0.7 then
 				Entity:Unlink(Ent)
@@ -573,15 +576,15 @@ do -- Linking ------------------------------------------
 		local Phys = Target:GetPhysicsObject()
 		local Axis = Phys:WorldToLocalVector(Entity:GetRight())
 
-		return {
-			Side = Side,
-			Axis = Axis,
-			Rope = Rope,
-			RopeLen = (OutPosWorld - InPosWorld):Length(),
-			Output = OutPos,
-			ReqTq = 0,
-			Vel = 0
-		}
+		local Link	= MobilityObj.Link(Entity, Target)
+		Link:SetOrigin(OutPos)
+		Link:SetTargetPos(InPos)
+		Link:SetAxis(Axis)
+		Link.Side = Side
+		Link.Rope = Rope
+		Link.RopeLen = (OutPosWorld - InPosWorld):Length()
+
+		return Link
 	end
 
 	local function LinkWheel(Gearbox, Wheel)
@@ -794,6 +797,8 @@ do -- Movement -----------------------------------------
 		local RClutch = SelfTbl.RClutch
 		local GearRatio = SelfTbl.GearRatio
 
+		if GearRatio == 0 then return 0 end
+
 		for Ent, Link in pairs(SelfTbl.GearboxOut) do
 			local Clutch = Link.Side == 0 and LClutch or RClutch
 
@@ -832,7 +837,7 @@ do -- Movement -----------------------------------------
 						if Link.Side == 0 then
 							Multiplier = min(0, Rate) + 1
 						else
-							Multiplier = -math.max(0, Rate) + 1
+							Multiplier = -max(0, Rate) + 1
 						end
 					end
 
@@ -872,6 +877,7 @@ do -- Movement -----------------------------------------
 		end
 
 		for Ent, Link in pairs(self.GearboxOut) do
+			Link:Transfer(Link.ReqTq * AvailTq)
 			Ent:Act(Link.ReqTq * AvailTq, DeltaTime, MassRatio)
 		end
 
@@ -883,6 +889,7 @@ do -- Movement -----------------------------------------
 				local WheelTorque = Link.ReqTq * AvailTq
 				ReactTq = ReactTq + WheelTorque
 
+				Link:Transfer(WheelTorque)
 				ActWheel(Link, Ent, WheelTorque, DeltaTime)
 			end
 		end