Freezing some fractured mesh objects

[stevenls]

Hi there,

I have a building that is made up of lots of different panels that I am trying to collapse.

The whole thing is fractured into decent sized chunks for the pieces to initially fall based on the next operators. I have the usual in place, Physx Shape, then the Physx Collision, Physx Bind set to glue, then I have a property test for the Bind Break which steps down into another even where there is some more fracturing.

When the collision happens, the fractures move, then there is some more fracturing and then over time as pieces come away the whole thing collapses, which is good but not what I want.

I want to have sections of the building still standing so it all just doesn't end up in a fractured pile on the floor.

As a second part to that I don't want ALL the fractured pieces to separate.  When you see a building fall the parts away from the impact points don't all just fly apart they fall in larger chucks and come apart at ground impact or stay in larger pieces.

So basically what I want to do is freeze some parts of the building and keep other sections together.  Just not sure what operators I should be using in conjunction with the physx stuff in place already to achieve this.

Thanks

[d4rk3lf]

For the "inactive parts" of the building:
- Just build some simple geometry that will cover (in it's volume) all parts of the building you want to be stationary.
Then add a surface test operator (set to volume inside), bellow PhysX operator, add the geometry you just built, and in the new event add PhysX Switch operator set to kinematic.
---------------
For the clusters of chunk:
Add a cluster operator bellow voronoi, and play with the options until you get the right size of the clusters.
Name the cluster channel whatever you want (for example "big parts").
Then add another PhysX Bind operator, and change it's ID to 1 (because you're already using PhysX bind with ID 0).
Scroll down and enable clustering, and choose the cluster name you previously typed (for example "big parts").
You'll probably want these groups of chunks to brake at certain force, so enable braking force, and play with the settings until you're happy.

[stevenls]

ok thank you, the first part is crystal clear.

Second part, not as clear but will have a muck around with it when I am back in front of the computer.

Thank you kindly.

[stevenls]

So I am going down a bit of a rabbit hole with this one.

I have a particle bind for the fractured shapes, that has bind breaking and a force setting
under that I have a particle bind for the cluster now.  Do I turn on bind breaking for that also and a force or that shouldn't have breaking, but I assume it would so it breaks on other impacts?

Just a little confused.

[d4rk3lf]

I would turn it on, in most cases.
You will probably want that even big cluster of particles brake when falling from great height, or if the collide with great force.
You'll probably want some of them to brake, and some of them to not brake.
You can disable display operator, and enable binding connection preview, so you can see how exactly binds look, in both bind operator.

Now it's all a matter of trials and errors with "bind braking" and force parameter.
If you have a very dense fractured mesh, the force should go up (sometimes even above 500k)... but that depends on the scale of the scene also, bind numbers and distance.

As I said.. trials and errors

Also, keep in mind that you have brake binds op... so you can even manually isolate certain particles (lie you did for inactive), and just send them to next event to brake.