I’m playing around with chaos destruction and modeling at the moment, and have a few questions that i cant find the answers to anywhere.
!! When fracturing objects like buildings with rooms or more complex meshes more than once into level 2 clustering or above the physics seem to break. Instead of breaking at the point of impact the entire mesh fractures at random places, as though the collision box covers the entire surface of the mesh(I know about level set collision and implicit setting- they are also different in recent UE updates, but that does not work past fracture level 1)
I tried to convex the mesh and geometry collection in fracture mode with no luck and just about everything else with no luck. I want the clustering effect and i want it to work at point of impact…
Also when optimising I find that using nanite in the blueprint editor simply makes my builiding mesh disappear and I cant click on it-this is supposed to work so idk what im missing and no i didnt use a nanite mesh to fracture i did it the ‘correct’
way
so if u can help ill obstensibly buy u a crypto-island that could speculatively possibly really exist
Ty!
What method are you using to break the building ? Are you using fields ?
Regarding levelsets, it is recommended in UE5 to use convex instead as they are more predictable from a performance and behavior point of view
Regarding nanite, I’m assuming you are referring to the Nanite option in the geometry collection asset? this should work out of the box
You can also enable nanite on a mesh ahead of time and create a geometry collection out of it after the fact the nanite check box will be automatically set when doing so
I have anchor fields to keep them in place and using a physical projectile with collision to fracture.
Nanite-yes im talking about the geometry collection but also a regular mesh, it happens on basic shapes like cubes too (the mesh becomes invisible) *i will share screen grab you will see only the pivot point.
I do use convex yes, still impact is spread all over mesh after 2 fracture levels breaking the realism, as though it convexed in the shape of a flat box or whatever with minimal vertices
you can even see they chunks sitting in thin air in the shape of the invisible box I spoke of…have been tweaking the settings every which way but still no luck
my damage threshold is index 0-35000 1-30000 2-20000 3-5000, mass is 2300kg per square meter. works nice visually watching it collapse and break apart etc.
BUT i cannot have the clustering effect and the ‘Invisible box’ around the structure is a prob
Anchoring:
I’m assuming that the anchor field is a box at the ground level ?
You can also set the initial dynamic state of few the ground pieces to be kinematic which has the same effect as using an anchor field
Floating pieces
Often this is an issue of the way the pieces under a cluster are connected to each other by their connection graph.
The minimal span Delaunay option ( default ) as limitations but should still be able to handle case like that
Sadly, in 5.0.3 there’s no option to visualize the connection graph at runtime, however 5.1 will offer a way to do it
5.1 will also introduce a better connection graph algorithm that has is more aware of the proximity of the pieces to connect and less likely to generate floating islands
Clustering
How are you clustering the buildings right now?
A way to work around the current limitation of the connection graph is to organize the clusters to better match the way the building is architected
I would recommend starting by creating a cluster for each level, then having maybe rooms / walls be clusters within the level clusters, and continuing breaking down those clusters logically into smaller ones to the desired resolution
Invisible box
Do you refer to an invisible collision around the building not following the concave shapes?
You can visualize the convex shapes in the fracture editor by selecting the convex tool in the toolbar and selecting the piece you want to inspect
If a cluster does not have an acceptable convex, you can delete it ( option in the convex tool ) and it should use the union of the convex of the children
If you haven’t watch them yet, I recommend the tutorial available in the learning section:
very helpful TY, will go ahead and try ur advice otherwise im sure 5.1 should make it a bit easier…will update if i need to but thx for now i will spend some hours studying the tutorials
Thanks @HenryMa96, I didn’t realize that the command was already in version 5.0.3
The image you show is a good example of over-reaching connection graph that can cause pieces to float in the air that the new connection graph will be able to better handle
