simready-foundation-conform-fet-003-newton

SimReady Conform FET_003_NEWTON

Purpose

Use this exact feature skill when the selected profile, validation report, or user request names FET_003_NEWTON. It repairs or stages rigid body physics (newton) conformance without drifting into another runtime contract.

Default to FET_003_NEWTON@0.1.0 when the user asks for this feature without a version. Use an older integer version only when the profile, validation report, or user explicitly pins it. If the report names a different FET_###_RUNTIME feature, switch to that feature's matching skill before editing.

Source of Truth

Before changing an asset or package, read:

• nv_core/tiers/simready_foundation_tier_core/simready/foundation/tier_core/features/FET_003_NEWTON-0.1.0.json
• nv_core/tiers/simready_foundation_tier_core/simready/foundation/tier_core/features/FET_003_NEWTON.md

Treat the selected JSON manifest as authoritative for dependencies and requirement IDs. Use the feature markdown for human-readable contract details, requirement links, samples, benchmarks, and adapters.

Feature Versions

Version	Dependencies	Requirements
0.1.0	None	RB.COL.001, RB.COL.002, RB.COL.003, RB.COL.004, RB.001, RB.003, RB.005, RB.007, RB.009, RB.010, NEWTON.COL.001, NEWTON.COL.002, NEWTON.MAS.001, NEWTON.MAT.001

Feature Adapter

When the input already conforms to the neutral base feature, prefer the deterministic feature adapter to author the runtime-specific data first (via the workspace upgrade command; see nv_core/sr_specs/docs/guides/feature_adapters/feature_adapters.md), then repair only the residual requirements below.

Adapter module	Adapter	Transition	Authors
nv_core/cip_specs/asset_handler_modules/neutral_to_newton	rigid_body_neutral_to_prop_newton	FET_003_STANDARD@0.1.0 -> FET_003_NEWTON@0.1.0	Mesh extents; NewtonCollisionAPI + NewtonMeshCollisionAPI on existing colliders; newton:contactGap = 0; NewtonMaterialAPI + default friction tuning on bound physics materials. Satisfies NEWTON.COL.001/NEWTON.COL.002/NEWTON.MAT.001.

• The adapter runs on a staged output stage and never creates geometry; it only annotates existing colliders.
• It authors NewtonMeshCollisionAPI (not NewtonSDFCollisionAPI). If the collider needs SDF-backed collision, or the base RB.* rigid-body data is missing, repair that manually per the Workflow below. Strict Newton isolation: do not author Mjc*/Physx* data or physics:approximation = "sdf".

Workflow

1. Confirm the input exists and identify the exact selected feature/version from the profile TOML, validation report, or user request.
2. Load the selected FET_003_NEWTON manifest and the feature markdown before editing.
3. Load requirement docs linked from the feature markdown for every reported failing requirement.
4. Create or use a staged output location unless the user explicitly asks for in-place edits.
5. Repair only the requirements listed by the selected FET_003_NEWTON manifest and its dependencies.
6. Rerun the same profile gate or the narrowest available feature/capability validation gate. If runtime evidence is required and unavailable, report that limitation instead of claiming a pass.
7. Summarize the selected FET_003_NEWTON version, changed files, validation evidence, and the first remaining blocker or next exact feature gate.

Feature Guidance

• NewtonCollisionAPI carries the shared contact tuning: newton:contactMargin (default 0, outward surface inflation) and newton:contactGap (default -inf = engine default; the samples author 0). Both must be non-negative when authored.
• NewtonMeshCollisionAPI is the ordinary mesh path (it inherits NewtonCollisionAPI). Newton reads the inherited physics:approximation; keep it at the intended value (convexHull, convexDecomposition, ...). newton:maxHullVertices (default -1 = exact hull, minimum -1) only matters when physics:approximation = "convexHull".
• NewtonSDFCollisionAPI is the SDF/hydroelastic path. It is mutually exclusive with NewtonMeshCollisionAPI on the same prim. When SDF tuning is authored, keep contact distances/padding non-negative, newton:sdfMaxResolution a positive multiple of 8, newton:sdfTextureFormat one of uint8/uint16/float32, and newton:sdfNarrowBandInner < newton:sdfNarrowBandOuter. Do not guess SDF tuning values when source data or policy is missing.
• Hydroelastic contact (newton:hydroelasticEnabled, bool; newton:hydroelasticStiffness, positive) is Newton-only (no PhysX equivalent to port). newton:hydroelasticStiffness alone does not enable it. When newton:hydroelasticEnabled = true, author an SDF source (newton:sdfMaxResolution or newton:sdfTargetVoxelSize) on the same prim — Newton requires one at parse time unless the mesh carries an attached mesh.sdf (a missing source is a warning, not a hard failure).
• NewtonMassAPI (NEWTON.MAS.001) is optional and applies on an Xformable (rigid body or collision Gprim), extending PhysicsMassAPI. Author it only to override neutral mass resolution: newton:inertia must be empty (no opinion) or exactly 6 finite elements [Ixx, Iyy, Izz, Ixy, Ixz, Iyz] with non-negative diagonal; newton:massModel is solid or shell; newton:shellThickness (default -inf = solver chooses) must be finite and > 0 when authored, and only matters under the shell model. Do not invent inertia values — derive them from source data or leave the attribute empty.
• NewtonMaterialAPI (NEWTON.MAT.001) applies on the UsdShade.Material bound to the collider via material:binding:physics, extending PhysicsMaterialAPI. Aligned with the UsdPhysicsMaterialAPI convention (PMT.001), validation checks placement only: the schema must sit on a UsdShade.Material that also carries PhysicsMaterialAPI. The Newton tuning attributes (newton:torsionalFriction default 0.005, newton:rollingFriction default 0.0001, and the newton:contact* attributes, default -inf = engine default) are trusted, not value-checked — author them as needed, or leave the contact attributes at the -inf sentinel (equivalent to omitting them).
• Strict Newton isolation (RV.011): do not author Mjc* / Physx* schemas or attributes, and do not set physics:approximation = "sdf" (use NewtonSDFCollisionAPI instead).

Samples

• sample_content/common_assets/props_general/obs_orange_a02/runnables/physics/newton.usd - single-mesh prop collider with NewtonMeshCollisionAPI, physics:approximation = "convexHull", newton:maxHullVertices = -1, and newton:contactGap = 0; and the bound physics material with NewtonMaterialAPI authoring all six Newton material attributes at their defaults.

Report Fields

Field	Meaning
feature	Exact feature ID and version, for example FET_003_NEWTON@0.1.0.
input	Source asset, package root, or package definition inspected.
output	Staged output path, or in-place only when explicitly requested.
requirements_repaired	Requirement IDs repaired in this pass.
validation	Command or inspection used to verify this exact feature.
status	passed, failed, skipped, or blocked.
next_step	The next exact feature skill or user/runtime evidence needed.