How to stop constraints exploding


I’m trying to make some procedurally generated physics based trees at the moment.

I have gotten to the point where my trees generate ok, I can have branches and a bunch of other stuff is working too.

I have worked out that you basically need to turn the physics off (I go through every mesh component and turn off it’s physics before I do this) before adding a constraint and a new mesh to the tree (which I need to be able to do at game time) and then turn it back on later, otherwise thing’s bounce around.

But as my tree grows it gets to the point where it just explodes crazy. I don’t know if it’s angular or linear drive, or projection or springs or WHAT is causing it to explode and fly around. I wish I knew

Any clues how to keep my constraints holding my meshes in place?

1st. Check that a simple collision is set up.

2nd. The very weakly visible coordinate systems of a constraint have to be exactly aligned to the limit coordinate system to null it. In other words, a simple ‘A constraint is starting outside of it`s limits’ would have reduced the time the physics system ate humanities lifetime significantly. As well as the tooltips. F.i. the 2nd (blue colored) Bone is the Parent and the 1st (red colored) is the Child.

  • Use ALT and Ctrl to Position the Constraint Reference Frames. Try ‘Snap’ or ‘Reset’.
  • Use Alt+Shift+Enter to check single components on desired functionality. The constriants should work properly in Simulate.
  • Activate Show Mass Properties, Show Bones to see if the correct bones are used
  • Rigging and bone scales from Blender might be an issue (as discussed here)
  • Do not use extreme values, the constraints are very sensitive
  • I tried to lower the collision depenetration velocity from 1000 to 500 in the project settings, which doesn’t feel bad right now

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