HAMMER THROW
An independent browser reimplementation of the World Athletics field event.

WHAT THIS IS
  The hammer throw is one of the four throwing events in outdoor track and field. Its
  modern form - a metal head on a steel wire with a rigid handle, thrown from a 2.135 m
  circle inside a safety cage into a 34.92 degree sector - is codified by World Athletics
  in the Book C - C2.1 Technical Rules. The sport traces to the Tailteann Games; it has
  been on the Olympic programme for men since 1900 and for women since 2000.

  This build is an ORIGINAL, INDEPENDENT reimplementation of that event. It reproduces no
  third-party code, artwork, audio or data files. It is not affiliated with, endorsed by,
  sponsored by or connected to World Athletics or to any athlete, federation or publisher.
  The eleven rival throwers in the competition mode are invented; no real athlete is
  represented, and their marks are drawn from a seeded random distribution.

  Records referenced: men's 86.74 m, Yuriy Sedykh, European Championships, Stuttgart,
  30 August 1986. Women's 82.98 m, Anita Wlodarczyk, 28 August 2016.

WHAT IS REPLICATED, AND FROM WHERE
  Every rule, dimension and judging decision comes from the World Athletics Book C - C2.1
  Technical Rules, which was downloaded from worldathletics.org and read for this build:
  TR 25 (competition format, time allowed, result, ties), TR 32 (throwing circle, landing
  sector, the trial, distance measurement, assistance), TR 36 (the hammer throw and the
  hammer itself) and TR 37 (the hammer cage). The implement table, circle and sector
  dimensions, cage geometry, failure conditions, the countback and the cut to eight are
  all implemented as written, and tested against the text.

  The thrower's mechanics are a model, not a rule. Where the model needed a number, it was
  calibrated against published championship biomechanics - the IAAF/World Athletics
  biomechanical reports for London 2017 and Berlin 2009, Otto's analysis of Sedykh's world
  record, Murofushi et al. (2005), Brice's 2014 thesis and Horvath et al. (2023). All are
  named in the in-app Sources panel with what was taken from each.

WHAT DIFFERS FROM THE REAL EVENT
  * The thrower is a point-mass model of a rotating system, not a human body. Its limb
    drawing is decorative and feeds nothing back into the physics.
  * The centre of the head's orbit is held at a constant height. Real throwers lift it
    into the delivery, so this build matches the measured RELEASE height rather than the
    measured low point.
  * The measured final turn lengthens again because of the delivery; this engine's turns
    only get shorter.
  * A head that strikes the NEAR side of the cage and still lands in the sector is a valid
    throw under TR 32.14 Note (iii). The game ends the trial instead, because a deflected
    hammer cannot be modelled honestly. The rule itself is implemented and tested.
  * Wind, latitude, altitude, air temperature, ground obliquity and the rotation of the
    Earth are not modelled. Horvath et al. (2023) compute those effects as up to 45 cm
    (pole to equator), 70 cm (2 m/s wind), 1 m (3500 m altitude), 35 cm (20 C), 17.4 cm
    (ground obliquity) and 1.5 cm (Coriolis across the sector).
  * The player sees the throw at a slowed-down clock, because the release window of a real
    hammer throw is a few hundredths of a second wide.
  * There is no fatigue, no weather, no crowd and no officiating discretion.

PROVENANCE
  192 items are tagged in js/provenance.js:
    133 DOCUMENTED    (69.3%)  quoted from a source that was opened
     24 DERIVED                computed from documented values by a stated rule
     14 MEASURED               produced by this engine and re-measured every run
      6 CALIBRATED             fitted so the model reproduces a published observable
     15 RECONSTRUCTED  (7.8%)  my own choice, with nothing published to pin it
  Three of the documented items - standard gravity, sea-level air density and viscosity,
  and the textbook smooth-sphere drag curve - are general reference values rather than
  things taken from a document opened for this build, and are marked as such so the
  percentage is not flattered. tools-harness-page.js recounts the list from the shipped
  file and checks it against this file and against index.html.

BUILD
  Engine, renderer, geometry, icons and og-card are hand-written for this build. No
  third-party library of any kind is loaded, bundled or vendored: the WebGL renderer, the
  4x4 matrix maths, the meshes and the PIL artwork are all original. No network calls, no
  analytics, no cookies. The only thing stored is your best mark, in this browser's
  localStorage.

LICENCE
  See LICENSE.txt.