Cineversity

I have a simple assemby - a long vertical cylinder with a small diameter cylinder passing through it at right angles to form a pivot pin. The two cylinders are unioned together and the “boole"is set as a solid body. I have two cubes (one on each side of the tall cylinder) set as collision objects.

When I start the animation the assembly falls until the pivot pin hits the top of the two cubes and stops. So far so good.

If I cut the two cubes such that there is a semicircular hole cut out of the top, the assembly stops falling when it hits the edge of the cube - ie it doesnt fall into the cutout.‘If I cut the holes in the cemter of the cubes (or in the cubes’top edges) and position the assembly with the pivot pin in the cutout it of course flies out of the cutout.

How can I cut holes in the two cubes so the assembly is trapped with the pivot pin sticking though the two holes? I want the tall cylinder to hang between the “cubes” and swing about the pivot pin as it is hit by other objects (actually a Realflow fluid)

Hi andrada,

The key is here to set the Collider to Attribute Manager> Collision> Mode> Static Mesh. This will use the real geometry instead of a simplified idea of the shape.

Please have a look at the scene file
https://www.amazon.com/clouddrive/share/IL897u5EudivvOafHnpHkVAtePAUV1DGA30oQNEJ4B8

Let me know if there is another question, I’m happy to look into it.

Cheers

Thanks much

I do have another question if you don’t mind

Can the mass of a Realflow fluid in combination with an object be taken into account by the dynamics system?

What I really want to model is a “deer chaser” - (鹿脅し/Shika-odoshi in Japanese.) It’s the (usually) bamboo tube on a pivot where the fluid runs into the tube until it overbalances and dumps the water, then swings back into position making a loud noise that will supposedly scare away the deer as it hits a stone or something. I know I can (maybe more simply!) model this with keyframed animation, but I was curious to know if I could also model it with C4D dynamics.

So what I would need is a tube that is heavier on one (blocked) end than the other, let fluid flow in until it overbalances and dumps the fluid. Every time I’ve tried to build an object with assymetric mass distribution it seems as though the engine is calculating as if the center of gravity is centered in the object. Probably because I don’t know enough about C4D dynamics - Or anything else, for that matter. This is all about learning more about dynamics than producing a real result right now.

Thanks again

You’re welcome, andrada!

I do not have a license for Realflow currently available, so it is hard to tell.

But a quick search in their manual showed me:
https://support.nextlimit.com/display/RFC4D2/Ask+:+Fluids+and+Objects
scroll down…
Are RealFlow | Cinema 4D particles able to influence Cinema 4D dynamic bodies (rigid and soft bodies, cloth)?
No, RealFlow | Cinema 4D does not change the motion or shape of Cinema 4D dynamic bodies, but they are able to collide.
The definition of objects must be done inside of RealFlow, but I do not know much about v2.6, if that would work.

If not, my suggestion would be to fill the tube and get the time when the tipping point is reached. Animate the Tube accordingly, then fill it again.
OR just animate the tube as you needed it and fill it accordingly (faster or slower)

The Center of Gravity can be adjusted (Mass tab.).

If you would share a scene file, I could replace the water with spheres and try to get it working.

Let me know if that sounds like a good plan.

Cheers.

P.S.: Here is a rough sketch of what I have suggested above. You will find most of the parameters on default. (Water has not that amount of friction, etc, but for now, that is not important)

Screen capture of the editor view, cycling twice through a filling process, and two scene files (a simple version and a meshed one)

https://www.amazon.com/clouddrive/share/arTwRMa2Qe8Jt7OfBw8GbDPhGk6tqsvXmeAP0YGdt33

Thanks much

I folowed your thinking and set up a C4D emiter that dropped a few spheres into the open end of the tube and by playing with the mass of the spehere got the thing to cycle fairly well. The only inconvenient thing was trying to figure out how to get the emmitter to cycle on and off, but for this exercise I just duplicated the emitter several times with different start-stop frames.  Then I added a Realflow emitter and sure enough it dumps water on each cycle.

I set the spheres to “Invisible in renderer” and that made it possible to do all the dynamics in C4D. I think doing it this way looks better than if I’d just animated the tube - I wouldn’t have thought of the little bounce as the tube returns to the starting position and this way I can move theemmiters around a little to get some randomness into the animation.

https://drive.google.com/file/d/1rlcMLmit3GD6p53VTeUoOvs2c-HD4e8g/view?usp=sharing

You’re very welcome, andrada.

That looks already promising.

Can you share the emitter set up, so I can see what you have done?

I’m happy to look into it and provide some suggestions.

BTW, I have had sent an hour ago a scene to render… (edit:) and here is the one minute clip to showcase the results.
https://youtu.be/6RbvEZmlMwE
Scene file
https://www.amazon.com/clouddrive/share/UVj5LnhdUN8dnjOJwOOliN9YRuLGXltuEgn8g8d9Dfs
/edit

Cheers

Thanks to all your help I finally got everything working.

I also demonstrated to myself that if you tag a Realflow-C4D mesher correctly it will properly interact with C4D dydnamics. But SLOWLY - to the point where I don’t think it’s practical on my 16 core i9.

Here’s a link to the video   https://drive.google.com/file/d/1rna997TzdELDkBf3THsgPxZt2tYushPo/view?usp=sharing

And a link to the C4D file   https://drive.google.com/file/d/1rr1lFXno_IHS0Tpx6o6HtGR-xa1TIZNe/view?usp=sharing

I’ve had C4D since release 6 or 8 but this is the first time I’ve tried using the Dynamics engine, so I’d welcome any comments or suggestions about a better way to make this all work

The only problem I haven’t figured out yet is why the emitted sphere objecst won’t enter the hollow tube generated with the Lathe function.

Also - I haven’t come up with any way yet to make the realflow-C4D emitter move together with a C4D object.

Thanks again.

Hi andrada, thank you, and you’re very welcome.

Thanks for the file and video-clip. Very much appreciated.

The sphere doesn’t go into the tube based on the Emitter.4 size. While the Emitter.4 is active go the Attribute Manager> Emitter Tab and set the size to 25cm for X and Y. If you like to get the sphere a little bit deeper into the tube, set the speed in the Particle tab higher. I had good results with 250-300. Sphere Size 10cm. For Emitter and Emitter.1 (if positioned correctly) the same values will work in the same way of course. I’m not sure if that caching of the C4D set up might help at all to speed it up, since it is just a small set up with only a few objects involved.

The Realflow Mesher, if I remember correctly, can write for each frame a mesh into a hard-drive-based cache. So the first run should be slow, but then it shouldn’t be really a problem given your horsepower. But perhaps, if you have, use an SSD for the cache file. In my DIY fluid-sim, the Alembic file was 2GB for 400 frames.

Let me know if I can do anything else, I’m happy to look in it.

Cheers