Destruction and Cloth

Apex Destruction

Apex Destruction fractures a mesh into a hierarchy of chunks that break apart under impact. Assets are authored as Destructible Meshes, either fractured in-editor with Voronoi decomposition or imported from external tools.

It is a mature, well-understood system with a straightforward cost model: chunk count drives everything. A destructible with a two-level hierarchy and modest chunk counts is cheap; one with deep hierarchies and hundreds of chunks is not.

Key settings live on the Destructible Mesh asset:

• Depth controls how many fracture levels exist. Each level multiplies chunk count.

• Damage Threshold and Damage Spread control how readily chunks break and how far damage propagates.

• Support Depth determines which level participates in structural support calculations.

• Debris Timeout and Debris Max Separation clean up chunks after they settle. Set these. Chunks that never despawn accumulate until frame time collapses.

Instructional video on Apex Destruction

Apex Cloth

Apex Cloth is the PhysX-era clothing system, authored either through the in-editor Clothing Tool or imported from APEX clothing assets produced in external DCC tools.

The in-editor workflow paints cloth parameters directly onto a skeletal mesh: max distance, backstop radius and backstop distance. Max distance is the primary control — it defines how far each vertex may move from its skinned position, so painting it to zero pins a region and increasing it lets the cloth swing free.

Practical notes:

• Cloth cost scales with simulated vertex count. Paint a low-resolution simulation mesh and skin the render mesh to it rather than simulating the render mesh directly.

• Cloth is simulated per skeletal mesh component. Ten characters in cloth cost ten times one character.

• Cloth does not substep with the rest of the scene. Fast character motion can produce stretching that no amount of parameter tuning fixes; the answer is usually reducing how fast the attachment point moves.

NVIDIA Blast

Blast is NVIDIA's successor to Apex Destruction, and the more capable of the two fracture systems.

Official Blast Plugin Documentation

Blast separates the destruction graph from the physics simulation. A Blast asset describes chunks and the bonds between them; damage propagates through the bond graph, and chunks become physics bodies only once they actually detach. This is why Blast handles large structures better than Apex Destruction: an intact building is a graph, not a thousand sleeping rigid bodies.

Blast also supports runtime fracture, so the fracture pattern can depend on where and how the object was hit rather than being fully baked at author time.

Enable the plugin from Edit > Plugins > GameWorks, then use the Blast Mesh Editor to author assets.

Choosing

Performance

Destruction is one of the easiest ways to destroy a frame budget, because the cost is invisible until something breaks and then arrives all at once.

• Cap simultaneous debris. Set debris timeouts and maximum separation distances on every destructible.

• Budget chunk counts against the worst case, not the typical one. A grenade in a room full of destructibles is the frame you have to survive.

• Consider the instanced physics subsystem for debris. Chunks that have settled and no longer need individual actors can be handled far more cheaply as instances.

• Profile with stat physics while destroying things, not while standing still.

Licensing

Apex Destruction, Apex Cloth and Blast are NVIDIA GameWorks technologies inherited through the PhysX and NvRTX lineage. Their licence terms apply to shipped titles. See the GameWorks source SDK EULA.

See also

• PhysX

• Instanced Physics Subsystem

• Bundled Plugins

• Profiling