Newton 4.00

[zak]

Ok, waiting for Scene Collision/Compound Collision, i have completed all the rest of the conversion of my engine from 3.14 to 4.00
You can spend some minutes to explain the joint solver modes: jointIterativeSoft, jointKinematicOpenLoop, jointKinematikCloseLoop, jointKinematicAttachment. What they do and when to use one or another, thank you.

[Julio Jerez]

Ok scene and compound are all in. Sorry for late reply.

The different joint options are not too hard to understand.
This goes to our mission statement about the newton solver.

Basically the solver has a post prossesing pass that uses a linear time direct solver.
In the pass I try to use that solver for contact but it degenerated into a cubic time complexity.
Since late 3.xx I now only use this solver for joint and the iterative is only use to get the initial guess.

The linear time solve is only linear for joint arrangement than can be set like a skeletal structure. Typical cases are organic creatures, vehicles, and few others.

This is graph theory is known as an acrylic graph, which means a graph in which a node can only have one parent.

This creates a problem, which is the engine need to know which joints form close kinematic loops.
The engine usually does a very good job at figuring that out.
But there are cases where two of more joint can form a close loop, and those flag are use a the tide breaker.

Here is an example.
Say you have a character.
From the hip to the hands and feet, all joints form open kinematic loops.
But say now the character grab a weapon with two hands.

The weapon will have two joints, one for the right and another for the left hand.

One of those can be open loop, so in this case you probably want the hand that is at the triger to be the kinematic open loop. So you set that joint set that to be kinematic open loop.
And the other kinematic close loop.
Not the play can grab the weapon with one hand by disabling the close loop. And with both hand when yo active the joint.
I will be demonstrating this functionality soon.

The other options are self explanatory, like soft means do not use joint solver. Attachment for joint that be use to connect something to something else like a hanging lamp, but the joint all have limit.

One typical example of that is the pick joint.
It is alway set to kinematic close loop. This way it does not has to reconstruct the articulation each time you pick a body from the scene.

It is eassy to get how all that works because it is as I tuition as whe people who made animations and encounter similar problem with loop joint. So the use the notion of constraint.

I hope this clear it a little.