[Fixed]1.8.0 Simulation changes by undoing

[tatt61880]

Edit: (by tatt61880 on 2011.09.10 12:23)
Fixed in v1.9.9.9b. Thanks
-Tatt
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Edit: not fixed yet. Fixed!
I've uploaded scene for reproducing this bug.
[scene]46036[/scene]
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With both Phun(v5.28) and Algodoo(v1.6.0-).

Undoing changes the simulation.

[How to reproduce]

Before undoing, motor cannot rotate geom.
After undoing, motor can rotate geom.

i.e. This can be a kind of cause of non-deterministic.

[Matten]

I think it's something with the velocities of the object.
Algodoo stores the vels of the object, and maybe they're loaded wrong.

[electronicboy]

its a well known problem.
its caused by the "randomness" of a the physics engine.

[Mystery]

No, that is different. Watch the video.

[tatt61880]

I've uploaded scene for reproducing this bug.
[scene]46036[/scene]

[tatt61880]

Not fixed yet with v1.9.8b

[PhunWars]

Momentum ? Probably the object "stored" some of the angular velocity and kept it also after he undoed, and that energy helped the hinge

[emilk]

AHA! It took me a while to find the cause of this - but now it will be fixed! Well done tatt

[tatt61880]

AHA! It took me a while to find the cause of this - but now it will be fixed! Well done tatt

Did you mean that next Algodoo has no randomness? =)

[emilk]

No, I'm still not quite there yet - there will still be small rounding errors and souch that can have big effects over time (butterfly-effect).

This bug in particular was much more than that though - this bug caused the hinge motor to be off for a few time steps after an undo, if undoing to a running state. That's a big difference (as you could see).

[tatt61880]

This bug in particular was much more than that though - this bug caused the hinge motor to be off for a few time steps after an undo, if undoing to a running state. That's a big difference (as you could see).

Oops, sorry, I didn't notice that cutting geom is not something to do with this issue.
(This issue can be happened by undoing, as emilk wrote)