Joint demo: Body sleep bug

[FSA]

The spring-damped cube in the basic joints demo from Newton 4 look like to have a bug related to sleeping.
When you pull the cube down on the floor and release the mouse button, the cube seems like it went to sleep and wont move anymore. If you move it a millimeter up, it goes back to normal behavior.

Here's a video: https://youtu.be/ke_Bbl9nYws

[Julio Jerez]

Yes I am aware of that, I was fine a bug with the joint solver that David pointed out.
I disabled the limit on the spring until I get it fixed.

Hopefully I do it today.
Thank for the report.

[Julio Jerez]

You can check it out, I disabled limits for the moment just to test the spring.
I made it more like it was in 3.xx where the regularizer is set independently rather than calculating it from the spring damper parameters.
This may be less accurate, but is far more controllable. Plus any app can made the auto calculation if they want to for more accurate spring/damper behavior.

Later I will add the limits.

[Julio Jerez]

Now I added the hard limits.
I am not sure if this is a robust solution because it makes the mass matrix ill formed, but seems to work very well for now.
You can test it again and see if it is what you expect.

later I will test it with the vehicle suspension to see if in fact is robust with a more complex joints configuration like a vehicle that has many kinematic loops and extreme mass ratios.
I do not put my hope too high, but I have been wrong many time before, this will be one case where been wrong is actually good.