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Bounce animation with exact parabolic arcs

Key a bouncing motion on the active object from drop height, restitution and gravity: exact parabolic arcs, decaying rebounds, constant travel and optional squash at contacts. Use it for balls, props and motion tests.

Recorded render of Bounce animation with exact parabolic arcs

What this component contains

  • ATTRIBUTION.md
  • LICENSE
  • README.md
  • anim_bounce.py
  • component.json
  • graphcheck.py
  • meshcheck.py
  • preview.png
  • test_anim_bounce.py
  • test_package.py
  • verification/native.json

How it works

Operator
baltor.anim_bounce
Parameters
drop_height, ground_z, radius, measure_radius, restitution, gravity, fps, start_frame and 4 more
Result
Keyframes on the active object: location Z with free handles, location X linear, scale squash keys.
Blender
4.2 or later
Axes
Blender Z up, -Y forward
Units
metres

Recorded checks

blender 5.2.1 LTS (hash 9e2066aef7ef built 2026-08-25 02:12:34)

  • addon_install_and_enable
  • operator_runs_with_defaults
  • blender_data_matches_core
  • addon_disable_unregisters
  • script_mode_runs
  • clean_reopen_addon_file
  • clean_reopen_script_file
  • gltf_separate_export
  • engine_output_clean

Limits to consider

Point-mass free fall with a constant restitution: no air drag, spin, rolling or deformation physics. The squash is a stylized scale key at each contact, scaled with impact speed, and it lowers the contact key by radius times squash so the object stays on the ground. Motion is along +X on a flat ground only. Keys sit on fractional frames. Verified in Blender 5.2.1, where F-curves live in the action's channel bag; the 4.2 code path uses action.fcurves and was not run.