unity-physicscore2d-shapes-advanced

Use PhysicsChain.Create with a ChainGeometry built from your vertex list, or call body.CreateChain(chainGeometry, chainDefinition). The chain owns its segments and stitches ghost vertices automatically, with isLoop controlling closed loops.

PhysicsChain.Create creates an owned chain whose segments can only be destroyed together via PhysicsChain.Destroy. ChainSegmentGeometry.CreateSegments returns unowned geometries you attach as individual shapes, allowing per-segment destruction and mixing with hand-built segments.

Write vertices directly into the PolygonGeometry struct, set count, then call Validate() and check isValid before assigning it to a shape. This avoids the engine error that PolygonGeometry.Create logs on degenerate input and skips span ceremony in Burst jobs.

Yes, in Unity 6000.5.0b9+ assign a new ChainSegmentGeometry to shape.chainSegmentGeometry, which preserves contact state. For owned chains, PhysicsChain.UpdateVertices updates all segments but requires matching vertex count and isLoop.

Use PhysicsDestructor.Fragment and iterate fragmentResults.unbrokenGeometryIslands, creating a body per island. Test each island against a virtual ground segment with Intersect to decide whether it stays static or becomes dynamic debris.

Use compound shapes when multiple collision regions must move rigidly together, such as character capsules with ground sensors or vehicle bodies with wheels. They share one PhysicsBody, allow per-shape materials, and are cheaper than jointed bodies.