Enum SolverBackend 

#[non_exhaustive]
pub enum SolverBackend {
    Xpbd,
    Tgs,
}

Selects which rigid-body integrator PhysicsWorld::step dispatches to.

Both variants read and write the same RigidBody fields, so a world can be migrated between backends between steps without changing any other configuration. They are not numerically interchangeable — XPBD is position-based (Macklin/Müller) and TGS is a sub-stepping impulse-based projected Gauss-Seidel integrator (Müller et al. 2020, see the crate-internal solver_tgs module) — so the same scene produces different (both physically valid) trajectories under each backend. Pick one and stay on it for a given simulation; do not expect bit-identical replay across a backend switch.

Notes on the Tgs path

DistanceConstraints are enforced as bilateral velocity-level impulse joints (JointOriented in solver_tgs_hooks_6dof_oriented), solved every TGS inner sub-step alongside contacts, plus a Baumgarte position correction for residual drift — a genuinely different algorithm from XPBD’s position-based compliance solve, so the two backends converge to slightly different equilibria for the same scene (not a bug; see tests/analytic_tgs_wiring.rs‘s joint tests for both backends’ measured bands).

Pre-solve hooks and contact modifiers run once over the tick’s contacts before the solve (tests/analytic_tgs_backend_coverage.rs).

The world’s Joints are solved inside the TGS substep loop: after each substep’s impulse solve, the same position-level joint projection the XPBD substep runs is applied and its correction is added to the bodies’ linear and angular velocities (tests/analytic_tgs_joints_in_substep.rs).

• Requires the std feature (solver_tgs is std-gated, same as the rest of the TGS family). Selecting Tgs in a build without std is not silently ignored at the type level — the variant still exists — but PhysicsWorld::step falls back to running Xpbd for that build, since there is no TGS implementation to dispatch to. This is a documented, defined fallback (a different already-correct solver runs), not state corruption.

Variants (Non-exhaustive)

Non-exhaustive enums could have additional variants added in future. Therefore, when matching against variants of non-exhaustive enums, an extra wildcard arm must be added to account for any future variants.

Xpbd

Extended Position-Based Dynamics — the solver this crate has shipped since 0.1.0. Default.

Tgs

Sub-stepping impulse-based temporal Gauss-Seidel. See the gaps listed on SolverBackend itself before using this in production.

Trait Implementations

impl Clone for SolverBackend

fn clone(&self) -> Self

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Copy for SolverBackend

impl Debug for SolverBackend

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for SolverBackend

fn default() -> Self

Returns the “default value” for a type.

impl Eq for SolverBackend

impl PartialEq for SolverBackend

fn eq(&self, other: &Self) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl StructuralPartialEq for SolverBackend