Boole object animated intersection edge

[education-common]

Boole object, A without B, A and B are 2 spheres, B is animated and intersects with A.
As a result I get A with a moving hole in it (in the shape of the intersection).
I want to use the intersection edge of this animation.
If I was to use a single frame, I could just tick "select intersections" and press C to merge all and I would have a selection of the intersection edge. How do I do this for the animation, inother words how can I get an animated intersection edge? (I will use this animated edge to emit particles)
Thanks

[Dr. Sassi]

Hi education-common,

That animated edge is new in each frame, which means no motion blur or continuous data. So, I will discuss some options below.

There are options, perhaps to use the Curvature Node, but I didn't get a prominent clean line there. Perhaps bake an Ambient Occlusion (inverted), and use it with PMatterwave.

I checked to get an XPresso set up, whereby a Spline circle (as an Emitter) would sit between the two spheres, and the ratio in the distance is also based on the ratio in radius, while the calculation needs to be split into sphere B is outside or inside Sphere A. After a while, I thought that was a lot of math and how to communicate about it. So, I looked for something simpler. Here is an incomplete but working setup:
https://stcineversityprod02.blob.core.windows.net/$web/Cineversity_Forum_Support/2023_Clips_DRS/20230910_Circle-intersection.mp4

Here is the simple yet cleanest result that I found so far. … 01.c4d (in the link below)

Below is a little idea to have just the ring, and emit from it. Since the spheres are cutting into each other, changing the surface angle, the ring changes its width accordingly. But I assume you like to have it stable. … 00.c4d (in the link below)

This would lead to this option, not a bool, but a sphere with a round adjustable hole and a ring around. … 11.c4d (in the link below)

Files
https://stcineversityprod02.blob.core.windows.net/$web/Cineversity_Forum_Support/2023_PROJECTS_DRS/20230910_CV4_2023_drs_23_ANsr_00-01-11.zip

All the best

[entry-newspaper]

Not sure what plug you intend to use, to generate the particles. But couldn't you drive that emission, with a luminance-based texture? If you apply a pure white material, to the boolean "B" object, and have it subtract from "A". Something like XP would allow you to drive the emission, with a material, so if you simply made everything else luma-black, then maybe that would work?

[Dr. Sassi]

Thank you, entry-newspaper,

Your post showed me that I must make it more transparent, for example how to use the ring project file. Here is the Ring version from a Boole with Thinking Particles. (I left particles so far out as particles can mean a lot, standard, Thinking Particles, X-Particles, etc.

CV4_2023_drs_23_ANsr_21.c4d

All the best

[education-common]

super, thank you

[Dr. Sassi]

You're very welcome, education-common!

My best wishes for your project.