v0.1.0

0.1.0 (2026-10-25)

Changed

• Breaking: the family API shape. m2World is an opaque pointer,
  and m2CreateWorld(def, &worldOut) returns an m2Result. Every call
  on a world's objects takes the world first, and readers take
  const m2World*. Ids are {index1, generation}, with no world field.
  Creates, destroys, snapshots, restores, the journal calls and the
  polygon builders return an m2Result and write through Out
  parameters. The world table, m2WorldId, m2World_IsValid, the
  *_GetWorld getters, m2SetAllocator, m2SetAssertHandler,
  m2LastResult, m2_errorConfig and m2WorldDef.workerCount are
  removed. The allocator is part of m2WorldDef, which begins with its
  cookie and an ABI version that m2CreateWorld checks
  (m2_errorVersion). Worlds share nothing, so separate worlds may be
  created, stepped and destroyed on separate threads.
  (#12)

• Breaking: misuse counting. m2Counters.misuse counts the calling
  code's bugs: an invalid argument, a stale id, a writer called from
  host code. A stale id counts one misuse in every call, while a stale
  particle id counts nothing, since particles die on their own. Corrupt
  snapshot or tape bytes count nothing. Host code a replay runs (the
  task hooks and the allocator) counts like any other caller.
  Motor and limit calls on a joint without a motor or limit change
  nothing and count one misuse; for a distance joint, use
  m2DistanceJoint_SetLengthRange.
  (#13,
  #14,
  #15)

• Breaking: ranges. Defs, setters and tapes refuse values past the
  ranges in base.h, each listed in docs/user/limits.md: speeds up to
  1e5 m/s, masses from 1e-9 to 1e12 kg, time steps from 1e-6 to 10 s,
  M2_JOINT_REACH of 1e9 m, and the rest. These are the other refusals:

  • Body-local lengths beyond M2_HUGE (1e5 m) in shapes, chains,
    outlines and joint defs.
  • Substeps: more than M2_MAX_SUBSTEPS (64) in m2World_Step.
  • Body defs with a non-finite value, an unknown type, a negative
    damping or a zero rotation, and world defs with a non-finite
    gravity or particle setting.
  • Velocities on a static body.
  • Negative dampings, which used to be stored as 0.
  • Mass data whose fields do not fit together in
    m2Body_SetMassData.
  • Outlines: m2DecomposeOutline refuses an outline that touches
    itself, or one whose vertex comes within 0.005 m of an edge it does
    not end.

  (#17,
  #22,
  #23,
  #24,
  #25,
  #26,
  #32,
  #34,
  #40)

• Breaking: what a restore or replay accepts. m2World_Restore
  refuses a snapshot in any of these cases, and leaves the world as it
  was:

  • its arrays do not fit together (free queues, shape lists, owners,
    broadphase trees);
  • it holds shape geometry the world would not build;
  • its mass data is not what the body's shapes give it;
  • a body rotation in it is not of unit length.

  Replay refuses a tape record whose bool flags are not 0 or 1.
  Snapshots are format 3 and journal tapes format 4, so those written
  by 0.0.1 are refused.
  (#23,
  #27,
  #29,
  #31,
  #39)

• Breaking: the world hash. m2World_Hash and
  m2World_GetHashParts now also cover:

  • every setting the step reads;
  • the live slots, keyed by index;
  • the id pools;
  • the broadphase's fat boxes.

  So two worlds with the same hash step on to the same bits. Every
  hash value changes, and m2WorldHashParts gains a volumes part.
  Queries capped at a number of hits keep the lowest shape slots, so
  they choose the same shapes in every world that hashes the same.
  (#37,
  #38)

• Breaking: m2World_ShatterBody returns an m2Result and hands
  the count back through countOut, and m2IsNormalizedRot returns
  bool.
  (#19,
  #20)

Added

• m2DistanceJoint_IsSpringEnabled reads a distance joint's spring
  toggle back.
  (#21)

Fixed

• The host's floating-point setting. The library computes in its
  own setting (round to nearest, subnormals kept, every exception
  masked) on any host thread. A thread left in flush-to-zero,
  denormals-are-zero or another rounding mode therefore gets the same
  bits. Task hooks, draw callbacks and the allocator run in the host's
  own setting.
  (#44)
• Saturation in the step. Every velocity saturates at
  M2_MAX_SPEED, and every joint and contact impulse at
  M2_IMPULSE_LIMIT, and water and wind loads at M2_MAX_FORCE. A 2x2
  joint solve whose couplings would overflow solves its rows one at a
  time instead.
  (#42)
• Far-apart joints. A joint between two bodies far apart clamps
  its separation to M2_JOINT_REACH, where it used to leave NaN in the
  bodies.
  (#35)
• Rotations. Normalizing a rotation keeps its direction for any
  finite nonzero input. Very long, very short or infinite components
  used to give {0, 0}, NaN or the identity.
  (#23)
• Far particles. A particle far beyond the grid's reach no longer
  overflows its cell coordinate.
  (#28)
• Polygons. A created or set polygon is rebuilt from its vertices,
  so its normals are always the world's own.
  (#31)