Hello everyone,
When I was trying to make a simulation of falling of a rope using softbody, I noticed that there is a huge difference between results when using different subdivision levels on the same model (in my case it is a spline with different number of points). The settings are the same (tried to attach .blend file but (I don’t know why) failed). Does anybody know why this happens and what is the cure for this?
http://www.pasteall.org/pic/102274
http://www.pasteall.org/pic/102275
I consider that your results are expected. Using a higher subdivision means that the calculations have to be much more complicated - a subdiv of 1 increases the number of faces by 4, subdiv 2 = 16x more calculations.
Basically, use the best level of subdivision (if any) to get a nice simulation, and then add another subdiv AFTER the softbody modifier to give the cloth a better shape.
I understand that the more subdivs, the more calculations needed. But it’s unclear why the results are so different (in my case with a larger number of subdivs the rope jumps to the infinity… which is very strange). I run simulations while playing with parameters and I was using a “low-poly” spline for that. Had I used a “high-poly” spline, it’d have taken me my whole life to choose correct parameters. On the other hand, low-poly models tend to penetrate other objects (as far as I understand). Correct me, if I’m wrong.
Any suggestions why it happens so and/or recommendations on the physics workflow? 
Are your subdivisions coming from a Modifier? That’s what BiggR is assuming, and what I was assuming, until I noticed you’re using your softbodies on a curve rather than a mesh. What’s more, you can’t put a Subdivision Surfaces Modifier before a Softbody Modifier – Blender won’t allow it (you get an error message instead). How are you subdividing? Are you doing it in edit mode? Are you increasing the surface resolution?
I’ve tried to recreate this but I can’t get it to slow down like you’re describing. Please find a way to post that .blend and maybe we can be of more help!
Here it is: Rope.blend.zip (1.04 MB) (at least and at last I managed to upload a .zip archive).
Subdivision I made in edit mode and only to the spline since as you said it is impossible to use a Subdiv modifier before a SoftBody.
Baking that scene took less than a minute. How long is it taking with you?
Benu, with a low number of points it took me about a minute or two. With a high number of points – about an hour. There are both models in the file (just on different layers).
Baking was no problem for me (less than a minute for both). But on frame 7, the rope on layer 2 decided to fly off to somewhere.
Looks like a problem with the soft body edges. be careful to not use extreme values (like 0 and 0.999)
