Cineversity

Hello

I’m having an issue with a dynamics simulation that I want to have happen very slowly, but unfortunately I keep getting an “explosion”.
I set the Project Settings>Dynamics>General to have a Time Scale of 10%, and the Expert tab is set to 20 Steps per Frame.

I have a Random Effector with extremely low values making the dynamics triggered “At Velocity Peak”.  But no matter what, the initial “break up” is extremely strong.  I tried with a sphere as a collider as well, but no luck. 
I left all my Particle forces in there, but deactivated them.

https://www.dropbox.com/s/drppumifqt78ygq/BrokenGlass_Cine.c4d?dl=0

Thanks!
Alex

Hi Alex,

Please have a look at both files. The _51 is slow, the _52 is even slower, based on an continuously advancing offset of the MoGraph Cache.

Some notes:

The Dynamic Body Tag> Collision> Shape: Automatic is certainly always the worse idea for this kind of set ups. It takes often a Box Or Egg-Like shape around the chunks, and an explosion is the typical sign of it.
For the glass shards “Moving Meshes” should be used.

The Size iIncrement underneath of that parameter, should be held small, if an explosion happen.

A simple Main Menu> Simulation> Particles> Friction supports a slow down effect as well.

You might explore the Bounce values from both Dynamic tags as well.

——

I have no idea about the X-Particles use here. I have had for a short time an evaluation license, but after three times requesting a free license, just to support people here, I think I will not try again. It’s certainly a great product, but I can’t support anything of that here, sorry.

Have a nice Sunday!

Here are the two scene-files (one zip)
https://www.amazon.com/clouddrive/share/nKEzmtKNQg0vnrz7AUfayH99bn1aPQahrMStpo3sNLc?ref_=cd_ph_share_link_copy

Thank you Sassi!
I like the Mograph cache concept, because it gives me a lot of control, but I don’t completely understand it.  Does the Mograph cache store the dynamics information?  I noticed your Dynamics tag is not using cached data, so does that mean it passes the data to the Mograph cache?

Thanks!

Hi Alex,

The MoGraph calculations are typically done before the Dynamics. Per Frame. The next frame needs to implement things MoGraph is supposed to supply to the clones. Since it can’t just ignore the dynamics, it needs to know the last state of the clones. From there it adds everything that would have happen without the dynamics even. Then comes the next dynamic calculation. The next frame starts that all over again.

So, which cache to use? As usual, it depents. MoGraph Cache holds all needed information from MoGraph of course, and as the manual states, some parts should not cached otherwise. Dynamics excludes most MoGraph data, but contains collision data for example, if needed. To get more used to it, set up a simple scene, a sphere and a floor, and experiment with it. To start with complex scenes and run into problems will wear one down, and that is not fun. Small scenes are fast and most of the time much clearer.

https://help.maxon.net/us/#TMOGRAPH_CACHE

https://help.maxon.net/us/#DYNRIGIDBODYTAG-RIGID_BODY_GROUP_CACHE

https://help.maxon.net/us/#DYNWORLDOBJECT-WORLD_GROUP_CACHE

In the file above, the offset is progessively animated. Practically, this is like being in a train and walking in the opposite direction. The impression will be, that the movement will be lower, e.g., if the train moves as fast as the walker, the surrounding will not change/progress. Yes, to see that in a simple slider might be kind of abstract, but I hope it helps.

All the best