interaction

The rules for touching a thing — the pure half of b3d-interactive. Babylon-free, deterministic, unit tested, so what counts as "you used it" can be argued about without a scene.

Why this exists

tosijs-3d could shoot things long before it could touch one. b3d-button is a floating Babylon GUI widget, not world geometry you reach for, so doors, knobs, switches, levers and consoles had no substrate — the gap tosijs-3d-ensemble named as "almost nothing for building a PLACE, as opposed to a battle" (#36).

The rules, and why each is a rule

• Activation is press-then-release ON the thing. Not press. A press you drag off and release elsewhere is a cancelled press, which is how every real button behaves and how anyone recovers from touching the wrong thing. In a headset, where your aim wanders, this matters more rather than less.
• Reach is part of the rule, not decoration. A knob across the room should not be operable because your ray happens to land on it. Out of reach behaves exactly like not-over: no hover, no activation.
• Disabled means disabled, mid-gesture too. A press in flight is dropped if the thing is disabled under you — otherwise a door that locks while you are pressing it still opens.
• Vetoes are consulted at ACTIVATION, not at hover. A locked door still highlights and still reports being used; it just does not open. That is what lets lockable and interactive compose on the same piece instead of one knowing about the other (ensemble's ctx.feature() finding).