rotation tween anchors

Motion interpolation now uses a placement's local pivot. The anchor's stage position follows the authored tween progress; rotation, scale and skew follow that same progress. Translation is solved from the interpolated anchor and the current linear transform. Thus a turn around a stationary anchor keeps it stationary rather than interpolating the object's registration translation along a chord. Angles remain unwrapped and custom easing/overshoot is retained.

The shared implementation is q0s-format/src/motion_tween.rs. The editor's indexed renderer, software export, native player and timeline snapshots call it. Local anchors persist through copied/F6 keys and project history; moving a transform anchor records it on the selected placements. New motion tweens use the authored point or the artwork's default centre.

q1s v42 and vector q0s v41 add an optional local pivot after each placement's FX. Documents without pivots keep their previous writer revision. Old revisions are still readable. For old files, pure turns whose endpoints keep the default artwork centre fixed recover that missing pivot; translated-and-rotated moves are not assigned an arbitrary remote fixed point.

Input inspected: F:/Q0S/asdasdsd.q1s, original q1s v32, 60 fps, linear keys at frames 0 and 85, rotation 0 to 169.40 degrees. The old interpolation displaced the stationary anchor by about 340 pixels near the middle. Its recovered local point is (283.72577, 244.18343). Maximum displacement over frames 0..85 is 0.000068239 pixels after correction. The file is read without overwriting it.

The workspace compiles and the editor/player release binaries build. Native window interaction was not exercised; the supplied document's transforms and software-rendered middle frame were inspected. No tests were added or run. Existing test fixture constructors only gained the new optional field.

numeric rotation

Properties > Rotation (deg) uses the same anchor-preserving rotation helper as the stage handles. It resolves the saved local pivot, a current custom selection pivot, or the cached artwork centre, and compensates translation. A newly resolved pivot is stored only after the edit succeeds, including materialized hold-frame keys and rig-bound edits. The usual history snapshot covers the angle, translation and pivot together. Bounds are queried only when rotation changes, not on every idle Properties repaint.