Make realistic object coming out and going into water effect (i.e. water “clinginess” and resistance)

[Steve Bentley]

This is tough to get truly right in C4D – in fact its tough even in RealFlow.
What about using a displacement map and animating a grayscale movie with waves and droplets etc then using that to push the polys of the water around. It should give you better control albeit with higher render times due to the displacement level you may need to get it smooth.
Let the collider do its job to get the geometry out of the way of the foot but then augment the secondary animation of the water perturbations with a texture movie.

[Xavier Bonet]

Hi, Steve! Thanks a lot for your answer. Your idea sounds rather interesting. I’m going to try it out.

Any idea how I can smooth out the collider result, though? I don’t know if you were able to check out the project file I uploaded, but you’ll see the way the “water” behaves is not at all nice.

It’s true that I’m going to be looking at higher render times with the displacement, and I’m not sure if it’s worth it for that detail—I’m already using emitters for fire and smoke, and displacement on a couple of textures, so the project is render-heavy as it is. Still, I’d like to find a practical way of solving this for any future use, and your idea sounds like it could be just that. I’m also thinking of trying the Wind and Formula deformers to see how close I can get to something adequate without running my render too long.

Thanks!

[Steve Bentley]

I had not downloaded the file when I answered last time. Now I have. So its a miniscus look you are after – the sort of clingy way water crawls up anything it touches under surface tension right (that’s the only thing that “animates” in the file as far as I can see (what version of C4D was this done in?)

We’ve done exactly this in the past and used the technique I outlined in the first post. But you have to think of it as looking from the top down and where the leg interacts with the water.
A couple of ways to go about it.
You could tie a gradient to follow the position of the leg around in expresso – but the circular gradient would be mapped onto a plane or your water cube. As a straight render it would look like the person had two rings just above the ankles radiating out from their legs. But instead of a color map use the gradient in the displacement channel to make that water bulge up near the legs.
The other way is to animate that gradient by hand using as reference a temp render shot from the top down with just the legs and water (use a parallel camera sized to the cube of water for easy mapping).

If you want to keep using the collision you could turn up the divisions of the cube and make it an editable object. Then you can animate the friction and stiffness in the collider and you can also animate the steps per frame in the project settings. This will keep the water from jumping around once its settled.
I think too I’d use an invisible dummy leg linked to the real leg so the dummy moves with the real one. That dummy leg should be simpler than the real one and it should not have a foot – almost just a cylinder. Its the dummy you use for the collisions. If you drag the foot through the water in your current project you can see the foot is affecting the collisions too and it messes it up a bit.