Animate semantic state, not unrelated transform curves. Define phases, coordinate frames, velocities, and ownership before writing per-frame updates.
Build order
- Define the timeline phases and event boundaries.
- Choose the frame for each motion: world, subject local, orbital radial, docking axis, or camera shot.
- Derive target position/orientation from that frame.
- Use analytic kinematics for authored travel and springs for responsive convergence.
- Preserve world transforms when detaching children from a hierarchy.
- Separate translation, alignment, spin, and secondary debris state.
- Clamp integration delta and reset every state variable on replay/disposal.
Read references/procedural-motion-and-docking-systems.md for the launch, staging, docking, debris, spring, quaternion, and frame-rate-independent response implementations.
Non-negotiable rules
- Use elapsed seconds and
deltaSeconds; do not make motion frame-count based. - Derive orientation from direction/frame, then apply roll or spin as a separate quaternion.
- Decompose docking error into axial and radial components.
- Switch from spring convergence to an exact terminal pose at the end of a sequence.
- When reparenting an animated object, capture world position, quaternion, and scale before removal.
- Use seeded randomness when motion must be reproducible.
- Keep visual shake in a bounded envelope and separate it from trajectory.
Routing boundary
Use $threejs-camera-direction for shot composition and camera handoffs.
Use $threejs-procedural-vfx when the deliverable is primarily plasma, sparks,
or effect pooling rather than object transform motion.