Hinge Joints Alternative?

[josemendez]

Unfortunately my tests with ObiStitcher in trying to emulate some hinge of some sort have been underwhelming to say the least but I am not surprised as it was never made for this.

Even as a simple test, take the Barrels deformation demo scene and try and stitch 2 barrels together - no mater how I define the stich(es), the barrel will move and travel together without me even doing anything - similar to the dancing effect you can sometimes get with soft bodies in a scene 

Did you try setting the stitched particles to the same phase value, so that they don't collide with each other? Stitching them and making them collide will likely cause feedback (dancing) effects.

Also, I believe the only way to break a stitch is to disable it via the API. In my project, I need hinges to rotate on a single axis and break potentially - this is a physics game with soft bodies.

Unfortunately stitches can't break depending on force.

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@josemendez Last, how hard would it be to implement some hinge in Obi?

Hinge constraints remove rotational DOFs (degrees of freedom) from a pair of bodies. This usually requires fine control of angular motion per-axis, as well as proper inertia tensors (which Obi only roughly approximates). While particles in Obi are augmented with rotation to some extent, they're not yet fully rigidbodyfied so to speak. Implementing hinge constraints would take quite some time as core parts of the engine need to be augmented/modified. We will consider adding this in the future.

An alternative could be using dynamically attaching particle groups to rigidbodies, then using hinge constraints on those rigidbodies. Less than ideal, but I think it's the best workaround for now.