Contraption Builder: complete object/joint settings + sandbox upgrades

[SethMorrowSoftware]

Two commits. The first completes the per-object and per-joint settings; the second adds a batch of "compelling & customizable" sandbox features. Everything reuses existing Kit calls, follows the project's LiveCode conventions (p/t/g/k/u prefixes, no reserved-word identifiers), and is append-only on disk so older saves still load.

Commit 1 — Complete object & joint settings

Part inspector

• Independent dimensions per shape: width/height (box, image, plate, anchor), length/thickness (capsule), diameter (ball, balloon, bomb), replacing the single blind "Size" scale. Re-fit on the same body via b2kReshape, so joints survive.
• Exact numeric entry (click a value to type it) and +/− steppers, funneled through one setter.
• New physics settings: linear/angular damping and bullet/CCD.
• Settings grouped into tabs so the 8-row panel no longer overflows.

Per-joint inspector (new) — select a joint with the Drag tool to set motor (on/off + speed), limits (on/off + lo/hi), springs (Hz + damping), and rope min/max length, per joint kind.

Persistence — damping, bullet, and density now round-trip (density was previously lost on save and not copied by Duplicate), plus all joint settings.

Kit — added b2kMotorOff / b2kHingeLimitOff / b2kSliderMotorOff / b2kSliderLimitOff / b2kWheelMotorOff (existing wrappers only enabled features).

Commit 2 — Sandbox upgrades

Build & control

• Part rotation — an Angle control on the Shape tab tilts box/image/capsule/poly/plate (b2kMoveTo); build ramps and slopes.
• World gravity — a Gravity button cycles Normal / Low (moon) / Zero-G / Reverse / Sideways (b2kSetGravity), saved with the scene.
• Pause / Step — a new b2kStepOnce Kit command plus Pause/Step buttons freeze the sim and advance one frame at a time.

Customize & content

• Material presets — a Material control cycles Default / Ice / Rubber / Metal / Wood (friction + density + bounce together; label derived from current values).
• Launch velocity & spin — a new Motion tab sets a per-part initial push (speed + angle) and spin, fired when Run starts (b2kSetVelocity / b2kSpin).
• Adjustable motor power — the joint inspector exposes motor torque/force (was fixed) for hinge/slider/wheel.
• Three new sample contraptions — Catapult, Newton's Cradle, Domino Run (the Domino Run also showcases the new Launch feature).

The part inspector now has four tabs: Shape / Physics / Motion / Special.

Verification

Static checks (LiveCode can't run in this environment): handler start/end balance is exact (336/336); every property key has matching cases across all dispatch functions; the busiest tab (Physics) is exactly the row cap; the new Kit command references valid Kit locals; all save fields are append-only.

Suggested manual test in LiveCode:

1. Place a box → Shape tab: set Width/Height and Angle (tilt it); Physics: pick a Material preset and adjust damping/bullet; Motion: set Launch speed/angle/spin → Run, confirm it launches and spins.
2. Gravity button → cycle to Zero-G / Reverse → Run; Save, reload → gravity restored.
3. Pause mid-run, then Step repeatedly to inspect frame-by-frame; Pause again to resume.
4. Build a hinge → Drag-select it → raise Motor power and speed → Run.
5. Examples menu → Catapult, Newton's Cradle, Domino Run → Run each.
6. Save a scene with angles/launch/materials/joint power, reload → all restored; load an old save → opens cleanly with defaults.

Out of scope / possible follow-ups: keyboard shortcuts, sleep-threshold control, a polygon point editor.

🤖 Generated with Claude Code

https://claude.ai/code/session_01AyoQTVuyLtPMrR5oVW6FFr