Constraint Tools: decide how to unify them

[Nebual]

Currently SandboxPlus has both the Constraint Tool (modelled after Gmod's "(Easy) Precision Tool"), which can switch between any constraint, and standalone also has a Weld, Rope, and Wheel tool (which is basically just "make an axis" and spawn a wheel prop, right now).

The older Weld (and Rope/Wheel) tools create Sandbox.FixedJoint, rather than Sandbox.Physics.FixedJoint - the two have slightly different API's, and while the former appear to be a "component wrapping the underlying PhysicsJoint", unfortunately the inner joint is private so there isn't a practical way to convert between the two. We need to standardize on one set, so things like "Physgun unfreeze all connected" or "Dupe all connected" or "Break weld" can operate on 1 set of joints rather than 2.

Open Questions for debate:

1. Which type of constraint: Joint (component) or PhysicsJoint (underlying), should we use?
2. Is it helpful to players having "Weld" and "Constraint Tool - in Weld mode" as two separate tools, assuming they were compatible and did the same type of constraint?

[ninjrdevelop]

It looks Physics.FixedJoint might be the stronger of the two

E.g the PhysicsJoint class has the Collisions property, which would save us from using ropes 😅

[Nebual]

Sandbox.Joint (the component wrapping Sandbox.Physics.PhysicsJoint) has EnableCollision, which toggles the underlying PhysicsJoint.Collisions.
No-collide currently uses a rope because its a constraint I can otherwise "turn off" by giving it an extremely long length - I can't use FixedJoint just for nocollide since it would then be a weld too.

Lets compare in detail:

Sandbox.Physics.PhysicsJoint	Sandbox.Joint (base component wrapper)
❌ not findable without manual tracking like PropHelper.PhysicsJoints	➕ findable in component hierarchy
x	➕ Creates/Destroys the joint when its component is created/destroyed, which may be helpful for auto-handling serializing/networking/dupe scenarios ?
x	❓ AttachmentMode (Auto or LocalFrames), affects how it constructs itself in some way. May simplify some constructing code
❌ private	➕ exposes float LinearStress and AngularStress getters, which are how much current stress is applied to the joint

Sandbox.Physics.FixedJoint	Sandbox.FixedJoint (component wrapper)
PhysicsSpring SpringLinear	float LinearFrequency, float LinearDamping . ❌ lacks access to float PhysicsSpring.Maximum, which is "For weld joints only, maximum force. Not for breaking." ??? might not do anything anymore
PhysicsSpring SpringAngular	float AngularFrequency, float AngularDamping

Sandbox.Physics.HingeJoint	Sandbox.HingeJoint (component wrapper)
x	has a built in motor with MaxTorque, TargetVelocity, TargetAngle, "Fequency" (lol typo) + DampingRatio of motor

Ballsocket, Slider, and Spring (which is rope) appear to have an equivalent api, except two methods that look broken are hidden from the component version.

It does look like my Constraint tool may have backed the wrong horse. I'll look at trying to move it all over to using the component version.