How to constrain the hairs of Object 1, within the volume of Object 2?

Hey everyone!

I’m experimenting with Ice, Ice Cubes, and melted water . . . results so far below:


Ice cubes from home often have areas that look as if air bubbles radiated out from a point or line. I can simulate this with some hair applied to the faces of a meandering cylinder.

But i feel limited in the hair dynamics settings by the requirement to make sure they don’t extend outside of the ice cube.

Is there a way to set the ice cube as the “domain” so to speak (to use fluid dynamics term), of the second object?

I could theoretically apply the hair system, and use a nightmarish boolean system to only keep the union of each individual hair and the cube . . . but that would be insanely time consuming, right?

What obvious method am I missing here?

thanks!

It’s an interesting problem, and I think the ice cube is looking great right now. As for containing the bubble particles there’s a few ways. The particles (When using an object or group) are emitted from the faces according to the face normals, and are emitted from the objects origin. So you can play a game by changing the objects origin. Basically you tab into edit mode on the object and select all verts and move it. You sometimes need to experiement on the direction to see which direction the particles move, but by moving the origin (or moving the mesh around the origin) you can can force the spheres to be within the emitting mesh. You can also just change the system to emit from the volume, in advanced) this is probably simpler.

As for making sure the cylinder emitter is within the cube, you could just use snapping. Create a circle and snap it to the surface of the cube. Turn of fsnap and extrude a couple times, and then snap it to the other side of the ice cube. You should probably fill the ends of the cylinder for good measure, topology doesn’t really matter is it will never be rendered.

Now here’s the part I’m not 100% sure on. I think that the proper way to do it is to have the bubbles as part of the ice cube mesh, with the normals facing the opposite way they normally would on a sphere. You should be facing inward, toward the center) It’s kind of like a hole in the mesh with ice on the outside and nothing on the inside. So I guess, in theory you should create your sphere(s) with the normals flipped. Create the particle system, apply it, and then join the spheres with the ice cube.

I probably mis-spoke, the bubbles i’m trying to simulate is this (and thank you for the compliment on its current state):


the streams of translucent within the clear. Bubbles within a volume i get, i can fake that.

here’s what i’m trying to manipulate to both flesh out and keep within the volume of the cube:


I want those hairs to extend as long as possible, but always be within the volume of the cube (a seperate object from the long and narrow cylinder they’re generated from)

does that make sense?

Ah, I see. Well I guess you coule apply the system, join the individual hairs, and use boolean union with the ice cube. Don’t forget that when you apply a hair system, blender converts each particle into a new object, and also keeps the original particle system. That’s the opposite of what most applys do. So, in short make sure to hide the original particle system.

Or just make the hair objects a little bit smaller, and cycle through some seeds until nothing pops out. You could make the viewport color different so it’s obvious. Ice cubes are tough, I haven’t seen a lot of good ones, but I think you’re heading in the right direction.

In Particle Edit mode you can cut hair strands exactly at surface with the Cut brush.

paolo

I just assumed he was using objects, but if they are strands then of course you could just give it a hair cut.

Yeah Photox, I assumed he was using strands, but if they are object the only way is a boolean, as you suggested.

paolo

haha, Particle Edit Mode!?! right there in front of me the whole time.

awesome, thanks everyone!


i probably took it too far here, but my habit is to always take it all the way to NO, and bring it back to yes :slight_smile:

Looks really good. Try out a glossy floor with an hdri and you’ll be cooking with oil. I don’t know why I always assume the most complex scenario.

I know exactly how you feel. I usually get caught up in the clever solution rather than the simple one. Fortunately, i’m still living in the realm of simple Blender solutions for now . . .