Deforming geometry that progressively fractures initially and then those fractured chunks undergo successive fracturing?
The first part is the tricky bit as you need to interrogate your incoming deforming geometry and then cut it up in to sizeable chunks, deforming over time. Pre-cut and deform is the idea.
Once this is in play, you introduce rbd objects point by point in to the sim which at that time, freezing their deformation and cull that piece from the reduced deforming collider also feeding the DOP sim as a deforming collider.
Google Searches:
“fracture deforming geometry houdini”
“houdini progressive fracturing”
Interesting link here:
https://vimeo.com/65238554 [
vimeo.com]
Once the pieces are cut and in DOPs and you get the deformation handoff of rbd pieces in to DOPs going, you can hijack the Voronoi Fracture Configure Object DOP to progressively fracture the pieces as you will. This tool is designed to work with bullet rbd impacts or meatballs, but the logic is all “SOP Solver” so you can unlock the asset and add your own trigger logic if you find hijacking attributes doesn't work.
Or use carefully placed meatballs in the deforming rig to blow your pieces about and to trigger sub-fracturing if you want to use the Voronoi Fracture Configure Object DOP in stock form and enable the use meatball option.
