Solver-Integrated Deformation-Aware BVH Updates for Real-Time Soft-Body Simulation

Real-time deformable simulation relies on bounding volume hierarchies (BVHs) that must be updated continuously under mesh deformation. Existing BVH maintenance strategies are executed as separate post-processing stages, requiring repeated global scans of mesh geometry regardless of deformation locality. This design introduces unnecessary computational overhead and limits scalability in interactive applications. We revisit this design assumption and propose a solver-integrated BVH framework that embeds hierarchical maintenance directly into the physics solver's per-vertex update loop. By performing lightweight boundary checks during vertex updates and propagating changes only when bounds are violated, the method eliminates redundant full-mesh traversals and restricts recomputation to deformation-affected regions. We establish the correctness of the update for triangle meshes with shared vertices through a one-to-many vertex-to-leaf mapping, and we evaluate the approach across meshes ranging from a few thousand to 7.2 million triangles, multiple deformation regimes, a real XPBD cloth solver, baked skeletal character animation, parallel multi-core CPU execution, and a GPU compute implementation. Under static and localized deformation the method reduces BVH update cost by up to roughly 20 times relative to the refitting, kinetic, and dynamic fat-bound baselines, for example from 19 to 62 ms down to 2.9 ms on an 871 thousand triangle mesh at rest, while preserving collision-detection correctness on every frame. We further report end-to-end collision cost and identify the globally contact-rich regime in which a dynamic fat-bound hierarchy remains competitive, giving a clear account of where solver-integrated maintenance helps and where it does not. These results show that integrating acceleration-structure maintenance into the simulation loop is a more efficient and scalable alternative to traditional post-processing pipelines for real-time deformable systems.