Dragging cloth along path

Dear community,

I have searched qiute a lot in the internet and this forum I could not find a solution to the following problem:

I want to move a curtain (cloth) which hangs on let’s say 10 points at an arbitrary path. At the beginning of the simulaiton the curtain is open. I want to close the curtain by moving only the first hanging point along the arbitrary path. The second hanging point should start following the first point when the cloth between those two points gets under tension and so on until all of the hanging points are being pulled along the arbitrary path by the tensioned cloth (and not by my manual point placement along the path). Meaning, the hanging points should move along the path by being dragged by the curtain, like it happens in real life.

The same reality in the other direction - I want to open the curtain by moving the first hanging point backwards until it hits the second one and then both of them hit the third one and so on until the curtain is open again.

I hope I have described the problem clearly and I would be grateful if somebody could link me to an existing thread for this problem or help me to understand how to define this simulation.

I am using Blender 2.8 and I am a Blender-beginner.

Thanks for any help!

I don’t think the sim can directly do that. It would mean the ‘inner’ hanging points should just be part of the cloth but constraint to motion along one horizontal axis.

A workaround I found is to attach these hanging points to pinned one very far above, which has a similar effect:

curtain-closing.blend (4.3 MB)

Thanks, omgold, for your reply and for the idea.

I thought there is somthing basic that I do not see, but obviously it is not so simple to achieve this within Blender. Here is an example of what kind of things I am trying to simulate: http://eccon.biz/case-study/royal-tulip-hotel-almaty/.

You can see that the trolleys are moving along defined paths. During opening the roof (starting in the video from 1:10) only the lowemost trolley is moving up and picking up the next one and so on until the membrane is folded in the middle of the roof. During membrane deploying (starting in the video at 0:17) it works the other way round: The first trolley is moving down and the others are being speed controlled and stopped by the membrane tension/selfweight. When the first trolley reaches the end of the path, the membrane gets tensioned.

Maybe a workaround could be that every trolley moves along it’s own path, but in this case their interaction (picking up each other) and their stopping by the membrane tension would need to be controlled/keyframed manually?

I guess the opening direction shouldn’t be a problem, as you get the membrane tension from the cloth sim to stop the trolleys, but yes, the other way, yes, there might be some additional trick needed. In my example blend it worked without it, due to the bending stiffness of the cloth, but that is not guaranteed to happen.

What comes to mind is that using hook modifiers you can use separate objects to control the location of the ‘trolley’ vertices. (Maybe you want to have these anyway, for rendering). This gives you more options to control the relative movement with object contraints. Try ‘Limit Distance’, this might be what you need.