Phase 6 updates

Phase 6 · Slice 12 ·

WheelCollider

  • wheel_colliders (6000.3, the Vehicles module added to the conformance project): a wheel's defaults, sprung masses, and a 1000 kg car settling, accelerating on rear-wheel torque, braking and turning, plus a lifted car whose wheel spins up and stops. PhysX's vehicle SDK isn't in physx-sys's bindings, and Unity's own glue around it isn't public, so the wheel is Tassix's own model, fitted to the recording.
  • What Unity shows and the model does: the suspension's spring carries the sprung mass at its target position (a resting wheel sits there) and pushes by its distance from it, with the damper; sprung masses share the body's mass out to balance about its center of mass; a free wheel spins as I dω/dt = torque − wheelDampingRate·ω (I = ½·mass·radius²), and one in the air that nothing drives stops; slips are measured against the speed plus 0.1 m/s (a locked wheel at v slips v/(v + 0.1)); forward and sideways grip are independent, the friction curves times the tire's load (the suspension's plus the wheel's weight); a held brake stops the body it carries. Wheels step in four substeps before each physics step (Physics.Simulate too), and have no shape.
  • Checked: everything at rest, the lifted wheel's rpm (within 0.1%), accelerating within 5%, braking within 15%, a rolling wheel's rpm within 10%, turning within 25%. Not checked: WheelHit.force (Unity reports about two thirds of the load), slips (sampled from Unity's substeps), driven wheels' rpm while spinning up, the wheel's turned angle.
  • For the corpus: Mesh.CombineMeshes (mesh_combine, exact: an instance's submesh brings the vertex range its triangles span, through its matrix), CombineInstance, Mesh.indexFormat. The street racer now compiles and plays its menu with no exceptions (8 of 14 projects compile, 7 load a scene); its title's RectTransform and CanvasGroup animation curves and its TextMeshPro font asset aren't imported yet.
  • The renderer no longer panics on empty meshes (wgpu can't bind empty buffers; they get a placeholder that draws nothing).
  • Sample: wheels.json (a car driving circles, trails behind its rear wheels).
  • Next: IMGUI from the corpus, recorded in 6000.3; animation curves on RectTransform and CanvasGroup, TextMeshPro font assets and TMP_TextUtilities for the corpus; the remaining overloads as the corpus and plugins need them.