1.7.5- motorTorque and its forward compatibility issue

[tatt61880]

The meaning of motorTorque is difference between v1.7.5 and pre-1.7.5 (i.e. v1.7.4 etc.).
This fact causes forward compatibility issue.

v1.7.5 re-calculate motorTorque and save the value into phn file.
When you opened the phn-file with v1.7.4(or earlier version), the motorTorque is NOT re-calculated (It should be! but it's not possible...).

This can be a troublesome issue for Algobox users.
The behavior of simulation is not correct with v1.7.4 or earlier, if the scene was created with v1.7.5!

[Solution]
I suggested one of the solution.

Keep the current motor strength(=motorTorque) and add the variable for real motor torque, just similar with "mass and density".
And save current motorTorque into scene data and do not save realMotorTorque. (density is saved and mass is not saved).
"motorTorque" is not good name. However for forward compatibility, the name shouldn't be changed...

Maybe, "motor strength" should be renamed to "motor angular acceleration" or something.

[Sonic]

We have motor torque now?

[tatt61880]

We have motor torque now?

Thank you for your comment, Sonic. =)
I suggested the solution and created the picture before v1.7.5.

[Sonic]

Oh. So we don't have motor torque. I was going to ask what the difference between strength and torque was.

[emilk]

1.7.5 have "motor torque" in Nm, 1.7.4 and earlier has "motor strength" with the actual unit rad/s^2, but displayed wrongly as Nm. Now, both are/where serialized under the name "motorTorque" which leads to forward compatibility issues, i.e. scenes made in 1.7.5 will have wrong motor strength in older version, but old scenes should work fine in new version.

That's not optimal, but Algodoo has only ever promised (to varying degree of success) backwards compatibility - NOT forward compatibility. The same issue exists for spring strength and polygon inertia, for instance. Basically, my stance on the issue is this: upgrading is free, and so if you open a scene an it says "made in a newer version of Algodoo", you can just upgrade and presto - problem solved! Having forward compatibility for everything will just be too much work, and leave to much extra code in both the Algodoo source, and also in the serialized files.

[Sonic]

That makes sense. Good solution, I guess.

[tatt61880]

Basically, my stance on the issue is this: upgrading is free, ...(snip)...

I believe your stance is correct.
I also prefer KISS design principle.

However, upgrading is not free for Phun users, now. :s

Best regards,

/Tatt