Best practice for changing rope lengths and repositioning

[Holty]

Hi.

I'm having mixed results AFTER moving and changing the lengths of rope. Rope is fine and simulates well until I alter the position / rotation and change the length of the rope. Then it freaks out.

Just to double check my process (sanity check): 

1: Add Obi Rope to scene
2: Add blueprint 
3: Adjust to desired thickness via 'thickness scale' in the Obi Rope Extruded Renderer
4: Rotate the 'Obi Rope' object say 90 on Z so it's vertical and move to position
5: Adjust length with start and end particles

Thanks.

[josemendez]

Hi!

The entire process you're following is fundamentally wrong, let's go over all points one at a time:

1: Add Obi Rope to scene
2: Add blueprint 

These should be the very last steps, since adding a rope under a solver and setting its blueprint triggers the start of the simulation. You want to create a rope component and a blueprint, set the settings for both, and the last couple steps should be adding the blueprint to the rope and parenting the rope to a solver.

3: Adjust to desired thickness via 'thickness scale' in the Obi Rope Extruded Renderer

This does not adjust the physical thickness of the rope, it just scales the rendered thickness (as the name implies) which is for visuals (same as scaling an object in Unity does not make its mesh any bigger, it just draws it bigger). The physical thickness of the rope is specified by its blueprint. See rope blueprints in the manual.

4: Rotate the 'Obi Rope' object say 90 on Z so it's vertical and move to position

Altering the position/rotation of the rope transform at runtime has no impact whatsoever on the simulation, unless some control point in the rope is attached to it. The transform is only used at edit time to specify the initial position/rotation of the rope, once simulation starts it happens in the solver's local space as per the manual.

5: Adjust length with start and end particles

Not entirely sure what you mean by this, adjusting the start/end particles alone won't change the length of the rope in any way. It will just reposition the start/end particles but all other particles in the middle will stay at their original positions, and the number and length of constraints won't change at all.

Changing the length of the rope at runtime is done using cursors.

Depending on your use case, it might be simpler to create the rope entirely at runtime from scratch, specifying the blueprint's path (control points) as you see fit. The manual contains an in-depth explanation of how to do this, see:
http://obi.virtualmethodstudio.com/manua...ctors.html

Let me know if you need further help,

kind regards