hi guys, i need your help on this one, but first i must apologize for my english (not my mother language). The problem is that i need an electric cable with real gravity effect, below is a list of ingredients i use in my scene:

- 2 locators (to control ends of the cable)
- 1 NURBS curve with 6 CVs (to deform the cable)
- 6 clusters, 1 on each CV of the curve
- 1 NURBS cylinder with lots of spans for good deformation
- 1 wire deformer (put on cylinder and curve and Local influence = 1)
- 1 poly floor (passive rigid body)
- 2 little poly cubs (active rigid body)
- 1 gravity field

To deform the cylinder i`ve decide to use an wire deformer, so i`ll use that curve for this. To produce the deformation i`ve put a cluster on every CV of the curve (which is wire deformer). Now i`ve start to point constrain the clusters like below:

cluster_1 constrained to locator_1 (constraint value = 1)
cluster_2 constrained to cluster_1 and cluster_3 (constraint value = 0.5 for both)
cluster_3 constrained to cluster_2 and cluster_4 (constraint value = 0.5 for both)
cluster_4 constrained to cluster_3 and cluster_5 (constraint value = 0.5 for both)
cluster_5 constrained to cluster_4 and cluster_6 (constraint value = 0.5 for both)
cluster_6 constrained to locator_2 (constraint value = 1)

to use the gravity effect i`ve point constrained cluster 3 and 4 like below:

cluster_3 constrained to cube_1 (constraint value = 0.5)
cluster_4 constrained to cube_2 (constraint value = 0.5)

well every thing looks good but i want to be able to make the NURBS curve to have a fixed length, i mean if i move locator_1 up in Y i want cube_1 to follow according to curve length instead of stretching the curve, so i need to limits the gravity effect on the cube_1 in some way. Now the cubes don`t stop until then reach the floor and that`s not good.


any help, suggestion, comment will be greatly appreciated.