PhysX

Rigid bodies

• static, dynamic and kinematic actors;

• box, sphere, capsule, convex and triangle-mesh collision geometry;

• physical materials with friction, restitution and density;

• gravity, damping, forces, impulses and torque;

• sleeping, waking and active-body tracking;

• continuous collision detection for fast-moving bodies;

• collision filtering and simulation/query shape flags;

• contact, overlap and wake/sleep notifications.

Scene queries

PhysX provides the collision-query path used throughout the engine:

• raycasts;

• shape sweeps;

• overlaps;

• single-hit and multi-hit queries;

• object-channel, trace-channel and profile filtering;

• synchronous scene queries used by movement, weapons, navigation and gameplay systems.

Query cost depends on collision complexity, broad-phase population, filter callbacks and result count. Use simple collision for repeated gameplay queries and avoid requesting multi-hit results when only the first blocking hit is needed.

Constraints

The integration supports fixed, distance, hinge, spherical and D6-style constraints through Unreal's constraint framework. Available controls include:

• linear and angular limits;

• motors and drives;

• break force and break torque;

• constraint projection;

• collision enablement between constrained bodies;

• mass and inertia scaling;

• skeletal constraint chains authored in Physics Assets.

Character and skeletal physics

PhysX supplies collision queries for Character Movement and rigid-body simulation for Physics Assets. This includes ragdolls, physical animation, hit reactions, body welding and per-body collision configuration.

Vehicles

Vite retains the UE4.27 PhysX vehicle stack, including wheel simulation, suspension, tire friction, engine, gearing, differential and drivetrain configuration. Vehicle behavior is authored through the standard vehicle and tire data assets used by UE4 projects.

Modern toolchain support

Vite's PhysX libraries and build files have been updated for newer MSVC and Clang toolchains, including the Android NDK Clang path used by current Vite builds. Toolchain changes are validated with the physics test and stress workloads before release.

Fixed-timestep simulation

The optional fixed-timestep path decouples the simulation cadence from variable render frames and adds render interpolation. It is intended for projects that require a stable simulation delta or reproducible captures. See Fixed Timestep for compile-time setup and integration requirements.

Instanced physics subsystem

The instanced subsystem represents large homogeneous rigid-body sets through instanced meshes instead of one Actor and component hierarchy per body. It is intended for debris, shells, environmental objects and other high-count simulations. See Instanced Physics Subsystem.

Native actor path

Engine-level systems that already own compact simulation state can operate closer to native PhysX actors and avoid unnecessary high-level Actor/component work. This is a specialized integration path: ownership, lifetime, transform synchronization, collision filtering and teardown remain the caller's responsibility.

Substepping

Without substepping, the physics scene advances with the frame delta. Large or variable deltas can reduce contact and constraint stability. Substepping performs multiple smaller advances when required; its CPU cost increases with the number of executed substeps.

Choose Max Substep Delta Time from the fastest interaction that must remain stable, then set Max Substeps to cap worst-case work. A cap prevents a slow frame from creating an unbounded simulation backlog.

For a fixed simulation cadence rather than frame-triggered substeps, use the fixed-timestep path.