nx_part_solver_lib.nx

nx_part_solver_lib.nx -- ★CONSTRAINT-BASED PART PLACEMENT (operator method pointer 2026-08-12: arXiv 2406.11824 Infinigen Indoors organizes ROOMS with a constraint DSL + maximal-satisfaction solver; operator transfer: "use similar logic ... to organizing the generated elements of a human"). This is rung 1 of that transfer: parts are POINTS with radii; constraints are DECLARATIVE ROWS in a data file (rule 11 -- the anatomy lives in data, never typed coordinates in an emitter); the solver is deterministic integer constraint PROJECTION (fixed pass count, fixed order). The SAME engine is meant to assemble face/organ parts AND, later, furnish rooms and city blocks (one engine, bodies AND worlds). ★RUNG 2 (2026-08-14): EXTENT + ORIENTATION + ENVELOPE AS FIRST-CLASS PARTS -- the rung named from two directions on /world/procgen ("orientation + extent (parts are points today)" and W4 R1 "orientation + extents + envelope as first-class parts"). A part may now carry a BOX and a FACING, and three new constraints consume them, so orientation is SOLVED geometry, not decoration: turning a part swaps its footprint, which changes what it collides with and whether it still fits its envelope. Constraint rows (whitespace-separated, # comments): part <name> <x> <y> <z> <r> declare a part with an INITIAL (possibly garbage) placement extent <a> <ex> <ey> <ez> give a declared part HALF-EXTENTS (a box). Default 0 = a point. facing <a> <fx> <fy> orientation as an integer direction vector in the ground plane, snapped to the nearest cardinal. Default (1,0) = +x. attach <a> <b> <dx> <dy> <dz> hard: pos[a] = pos[b] + (dx,dy,dz) mirror <a> <b> bilateral symmetry about the x=0 plane: ax=-bx, ay=by, az=bz station <a> <lo> <hi> a.z clamped into [lo,hi] (the anatomical station band) clear <a> <b> <mind> centre distance >= mind (no-intersection of POINTS) inside <a> <b> <maxd> centre distance <= maxd (containment; a moves toward b) band <a> <b> <lo> <hi> centre distance inside [lo,hi] ratio <a> <b> <c> <d> <num> <den> [tol_permil] dist(a,b) : dist(c,d) = num:den noclip <a> <b> [gap] BOX no-intersection: the two oriented footprints must be separated by >= gap on some ground axis. Parts whose z-intervals do not overlap are exempt (different storeys never collide). envelope <a> <b> box a lies ENTIRELY INSIDE box b -- the room shell / city block / skull cavity. Only a moves: an envelope is GIVEN, not solved. face <a> <b> a's facing is the cardinal direction toward b (chairs face the table, buildings face the street). Orientation solved from geometry, never typed. ORIENTATION IS EXACT BY CONSTRUCTION, AND THE BOUND IS DECLARED: facing snaps to the four cardinal directions, so a rotated footprint is an exact swap of ex/ey -- no trig, no fixed-point error, and the measured violation is the true violation. Arbitrary-angle boxes need an exact-enough integer rotation contract (the fleet's rc_sin_q14 is a Bhaskara approximation, ~2 permil -- fine for a camera, NOT for a predicate whose whole contract is an exact refusal). That is the NEXT rung, and it is named, not claimed.