fix(physics): make upright a real state, and actually start ships on the floor

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Six rounds of reward shaping (~700M steps) failed to produce upright ground
driving. A critical review of the simulation rather than the reward found
why:

1. The hull was a 1x1x4 box with inertia (1,1,1) and no restoring torque
   anywhere, so belly-down and rolled-90 were geometrically identical
   resting states. "Upright" was not a physically distinguished state at
   all - the reward was paying for a property the simulation did not have.
2. ~65% of episodes spawned ships via _random_position, which samples Y
   uniformly over the full 18m volume (mean ~8.7m). The measured
   airborne_fraction ~0.44 was largely that spawn distribution, and every
   ground-handling term fades out above 3m, so the shaping being tuned
   barely ever applied.
3. air_drill_chance 0.20 spawned deliberately unreachable-without-climbing
   states in the stage meant to teach ground driving, and its own
   air_touch_fraction (0.0002) shows the drills were never solved.

Fixes land in the physics and the task distribution, not the reward:
- ship.tscn: hull 1x1x4 -> 1.6x0.6x4 so it has one stable resting face;
  inertia (1,1,1) -> (7,1,7), physically correct for the hull, making
  tumbling reluctant while keeping yaw snappy.
- ship.gd: new altitude-faded righting torque (spring-damper toward
  belly-down, faded out by 3m so aerials keep full attitude freedom).
  This is the grav-plating analogue of Rocket League's auto-righting and
  helps human pilots land cleanly too.
- training_mode.gd: new ground_start_chance branch spawning ships level and
  resting on the floor with a floor-level ball - the state the handling
  stage's rewards are actually written for.
- generation5.py: ground-start-chance 0.50, air-drill-chance 0.20 -> 0.0.

Reward terms are left exactly as they were; they should finally pull in a
direction the ship can go.

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This commit is contained in:

Josh Creek

2026-08-16 08:17:16 +01:00

parent 033a774c92

commit ea756bd5ba

15 changed files with 146 additions and 270 deletions

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Game/bots/20260814-1939-gen5-s4-handling.json

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Game/bots/20260815-0156-gen5-s4-handling-retry1.json

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