Very weird behaviour of a Limit Location Constraint

Hi,

While working on a Third version on my 4x4 Autodrive system, I have encountered a
Very weird behaviour of a Limit Location Constraint.

I have put on these links below two Blend files. They are indentical, except the fact that one has been saved with the Limit Location set with its influence factor to 1.0, and the other one has been saved with the Limit Location set with its influence factor to 0.0.

The constraint (look at the right upper corner of the screen) is applied to the red object named Axle-Front. You can check the effect of the constraint by going one frame forward. When the constraint is not efficient, the whole system is delayed and the red object named Axle-Rear appears separated from the blue object named Bar-Rear.

  • When the file is saved with the influence of the constraint set to 0, when you reload the file the constraint does its work only if you set it to 1 : normal behaviour.

But you can notice 2 abnormal things :

  • When the file is saved with the influence of the constraint set to 1, when you reload the file, the constraint does its work only if it is set to 0 !

  • If you have saved the file with the constraint set to 1, as the constraints works correctly with the influence set to 0 when you re-open the file, you could expect that the constraint is useless.

So, try to delete the constraint. You will see that it doesn’t work : The unwanted delay in the rig appears again ! :eek:

What do you thing about this problem ?

http://3d-synthesis.com/Bugs/WeirdConstraint-ON_01.blend

http://3d-synthesis.com/Bugs/WeirdConstraint-OFF_01.blend

Thanks in advance for any idea. Do you think it’s a bug ? :confused:

Philippe.

Well, no response at all…

Meanwhile, I have encountered one more stange behaviour with constraints :

An object with a parent and having two Copy Rotation constraints pointing to two objects has its dimensions changing during the animation !

It appears in the 3D view and in the Transform panel values as well !

I had never seen that before ! :eek:

Sheesh… your dependency cycles are worse / more numerous than I imagined from just reading the description. Just to remind you again: Blender’s dependency graph is stupid when it comes to resolving any dependency that it perceives to be even slightly ‘cyclic’. Very weird bugs often result from messing around with this.

Well, I know that there are several dependency cycles in my setup, but they are absolutely necessary. I haven’t been able to found a solution to get the same result without them.

Since I posted, I have modified the setup and avoided the bugs (it still has cyclic dependencies though), but it is very strange to get these phenomenons, even because of dependencies.

A different behaviour of Blender according to the value of the influence cursor when the file was saved, or object dimensions changing during the animation only because of rotations constraints don’t seem to be very logical ! :eek: