cascading fractures

[Mdonovan]

hey guys ... i am trying to figure out the best way to cascade a voronoi fracture ... so I can fracture the fractured pieces with control ... I am sure this has been done ... any pointers would be great ?

 

thanks

 

M

[lukeiamyourfather]

It's a feature that's included. What's your question? What specifically is the problem you're running into?

[Mdonovan]

I was not aware there was a tool for what. want to do .... I have a fractured object that I have breaking apart using a glu network ... I want to fracture the resulting pieces of the first fracture in a controlled manner (timing wise) , and then fracture those pieces .... and so on and s on until I am off with incredibly small pieces at which point I will emit sand or dust.

Hope that makes sense.

[djiki]

Scatter some points (not much, let say 10 for test purpose) on your geometry by Scatter SOP and connect its output to VoronoiFracturePoints SOP at second input "Impact Points". At first input connect your geometry. Adjust Impact Radius to such value you can see clusters impact areas in blue. Change other parameters to see how they affect on new points generation which will serve for fracture. You will probably need to increase resolution of volume and number of points but that depends on details of your geometry. Also you can adjust distribution of newly generated points (inside, on surface, outside). Finally, output from VoronoiFracturePoints connect to VoronoiFracture SOP at second input and on first input connect your geometry. On VoronnoiFracture  node turn on clustering. It will allow that small pieces of fracture stick together in clusters. You can use ExplodeView SOP to better visualize clusters and pieces. Geometry prepared on this way can be simulated to achieve goal you want. First, clusters will be separated but keeping all small pieces they made of still glued. Eventually all pieces could separate by applying more forces or decreasing glue strength. 

[Mdonovan]

djiki ... ok ... so its really still one fracture ... just using clustering to control the glu breaking.  Thanks I will give that a try.

 

M

[djiki]

Yes. That's it.

 

In general that's just "two levels" fracturing but inside single sim. The first (larger parts) are clusters and second is pieces of clusters. If you can control the rate of how fast clusters losing their smaller parts you get smaller, and smaller clusters over time which could looks like there are several stages of fracturing. Depends on effect you want, this way you get larger parts loose their small pieces which is more crumble-like effect. If you need that every stage gives you approx half sized pieces then try to divide your whole geo into let say 3 or 4 large pieces and create point attribute glue with value let say 1, then repeat process but instead to fracture your initial geo, fracture that already fractured pieces into smaller ones with same method and give their's points  value 2 for glue, repeat that for stage 3 and so on. So smaller the pieces higher the glue value. After several stages your geo is prepared for sim. At first impact force (or manually  applied force) geo will breaks on larger clusters because their glue strength is smallest, and so on....      

[HM_2020]