Shape Cage crushes Unreal static meshes in the vertex shader

A new Unreal plugin bends, dents and squashes static meshes at runtime without a soft-body solver, doing the whole job in the material's World Position Offset. For anyone who has ever wanted crates that crumple when something lands on them, the cost is a handful of shader instructions per vertex and about twelve bytes on the wire.

Shape Cage, by Woziva, fits a 27-point cage around any static mesh. You add the component to the actor, drop the supplied material function into the mesh's material and plug its Offset output into World Position Offset. From there the cage takes an impact's position, force and direction and works the resulting shape out arithmetically rather than solving it. Three modes cover the common cases: box for crates and panels, sphere for balls, curtain for cloth. The eight handles can also be dragged by hand, and a shape crushed in the editor can be saved and replayed later from a single node.

The networking is the interesting part. The server sends what happened rather than the geometry, roughly twelve bytes per dent, and every machine runs the same maths to arrive at the same shape. A player who joins late still sees the crate as it currently is, and an object that has stopped moving sends nothing at all. On the render side there is no CPU mesh work and no skeletal mesh involved; it works with Nanite and without, and the component switches its own tick off two frames after a shape settles.

The caveat is inherent to the technique rather than to this implementation. World Position Offset moves vertices at draw time, so the collision primitive never moves with them. A crate flattened to half its height still blocks a character at its original size, and a line trace will not find the dent. That is fine for set dressing and wrong for anything the player has to climb over or shoot through. It is static meshes only, too, so it has nothing to say about character or skeletal work.

Practical details: Unreal Engine 5.6, 5.7 and 5.8, Windows only, and between €51.14 and €92.08 depending on licence. The 5.6 floor rules out anyone still shipping on 5.4 or 5.5. The listing went up on Fab on 26 August and was last updated on 2 September; 80 Level covered it this week. The listing sums it up as a "soft-body look, without soft-body cost".