How to simulate a long sequence of Cloth simulation?

Support Particles and Physics Simulations
1

So I have an animation ready for say 1500 frames. Minus 100 frames I have kept in the beginning for the cloth to settle down first. My question is can I do the simulations in increments? Like not simulate the whole thing in one go. And still have a final baked simulation, like in the same place and not in parts.

2

I’ve never tried this, but it would be easy enough to test. My gut feeling is it would not allow for a continuous baked sequence, at least not reliably. Why the need to break the sim into segments?

3

Not say segments. But it would be better than having a sim on for like the next 24 hours.
I thought I could do it in parts. Test simulating small segments where I feel the cloth would not react the way I want it to.
All in all test some of the parts. And then do the whole 1500 frames in say 3 parts.

4

The problem as I see it is that each part (or segment, same meaning here) would have a different starting configuration for the cloth mesh, since in a continuous sim each frame is dependent on the result of the preceding frame. How would you get the cloth “into shape” at the start of each part, to match the end of the previous part? Again, some testing is in order. Maybe using “Update to frame”?

When making “Kata” (see my sig for a link), I often had this problem, and converted the cloth frame to a shape key which I then applied to the mesh and started the new sim from that point. But the results were never the same as running the sim continuously, since the initial conditions were different, and even small differences can create a very different result.

5

Exactly my point. I knew that would be the problem. That’s why started the thread.
And I tried the update to frame thingy. Doesn’t work. Each time it refreshes even though you have a previous sim saved.
Oh well guess have to run the sim all the way multiple times to test and then do the final sim.

Thanks for pooling in though.

6

One thing to look into is how to optimize your Cloth simulation settings. I know Cloth can be time-consuming, but 24 hours for 1500 frames seems excessive unless you have a rather weak computer (I did for years and it was nightmarish!)

Example: I’m currently running a Hair Simulation (based on the Cloth sim algos) and 2 Soft Body sims with a 1355 frame range, and they never take more than about ten minutes even when I bake them all at once.

7

Haha. Nah man it won’t take 24 hours. Excuse my language, I was being sarcastic. I have an old HP Z400 Workstation. It runs okay. Though not as good as I want it to be. Have to get myself a new one.

For now it took 20-30 mins. to do 500 frames.

8

Maybe you know these already, but here are some sim-baking optimizations:

  1. Have only your Cloth/SB/Hair object in the 3D view during a sim. Put everything else, including collision objects, on separate hidden layers (making sure the sim object & the collision mesh share a layer!).

  2. Use the least dense mesh possible to accomplish your sim, e.g., use simple topology wherever you can. Thus, make sure any Subsurf or other Generating modifiers FOLLOW the sim modifier in the stack. Disable these during your sim bake.

  3. Use Collision only if necessary, otherwise disable it entirely if you can.

  4. If Quality is a parameter, use the lowest acceptable value. Use Cache Steps greater than one whenever possible.

  5. Etc., etc., etc. :wink:

9

Thanks man. :eyebrowlift2: