Tips for Making Particles move down Mesh

Hey! I’ve got a problem I’m hoping someone could help with. I’m looking to emit particles from only a portion of a mesh, then to make the section that’s emitting particles move down the mesh. That is, the mesh itself stays static but the part that’s emitting particles changes - like this:

The reason for me doing this is I’ve got a 3D scan of someone’s head which I’m planning to make melt - with the particles coming off the flesh as it ‘burns’ down… I thought I might be able to use shape keys but as far as I’m aware you can’t keyframe them. :confused:

Any help would be much appreciated!

I would probably create another emitter object, a mesh with a decent number of verts. Move the verts so they are pretty close to the face. Then shrinkwrap modifier on the emitter onto the face object. Keyframe the emitter moving down, and maybe even shapekey it. Then add the particle system making sure you check ‘use modifier stack’ checkbix

This is really cool… thanks for the advice on that. I’ve got an issue tho where some particles don’t seem to move from the main mesh after being emitted. I’ve turned off gravity for the particles and set a high normal emitter geometry but some still get stuck on the mesh.

This is the main look: https://imgur.com/0k5pe4C

And these are the particles that don’t seem to budge… https://imgur.com/lBj3w17

Don’t suppose you could advise on this? Apart from that it works amazingly!

PS. Additional question - is there a way to make the main mesh disappear as the shinkwrapped mesh passes over it? To make it look like it’s disappearing away into particles (kind of like a Thanos dusting look… :D)

Nice work. Can’t say for sure why those particles are staying put. The general rule of thumb for particle system is to spend an hour or so saving different versions, checking checkboxes, sliding sliders and changing configs, re-baking and having a look. I’d literally just start making random changes all over and re baking.

Making the mesh disappear can be done many ways, here’s a thread from 6 years ago, but the ideas still work today!