verify_r2_layout_sim.py

"""R2-3 v1 — procedural-cell layout certification (CI-safe, pure math).

Certifies procedural_cells/hash01 (golden_render.py, mirrored bit-for-bit in
canvas-engine.ts): organic materials lay as individual cells with per-cell
grain, tone jitter, running-bond stagger, and a generated seam — so
repetition is impossible by construction.

Checks:
  1. determinism: identical inputs -> identical layout (golden stability)
  2. hash01 is JS-bit-exact on reference vectors and well-spread in [0,1)
  3. no repetition: neighbouring cells get distinct grain offsets and tones
  4. running bond: consecutive rows are staggered, not aligned
  5. seam geometry: cell borders are grout, cell interiors are material,
     and the seam width matches grout_frac
  6. anti-aliasing: a coarse footprint widens/soften the seam instead of
     aliasing it
"""

import numpy as np

from golden_render import apply_reflection, hash01, procedural_cells

RW, RH = 120.0, 80.0   # repeat cell in plane units
TW, TH = 256, 256
GF = 0.012


def field(px_per_unit=1.0, footprint=1.0, n=400):
    """Sample a regular grid of plane points across many cells."""
    xs = np.linspace(0, 20 * RW, n)
    ys = np.linspace(0, 20 * RH, n)
    gx, gy = np.meshgrid(xs, ys)
    rx, ry = gx.ravel(), gy.ravel()
    fp = np.full_like(rx, footprint)
    return rx, ry, procedural_cells(rx, ry, RW, RH, GF, TW, TH, fp)


def main():
    ok = True

    # 1 — determinism
    rx, ry, (u1, v1, t1, g1) = field()
    _, _, (u2, v2, t2, g2) = field()
    good = all(np.array_equal(a, b) for a, b in ((u1, u2), (v1, v2), (t1, t2), (g1, g2)))
    print(f"  [{'PASS' if good else 'FAIL'}] deterministic layout")
    ok &= good

    # 2 — hash01: JS-reference vectors (computed with Math.imul/>>> semantics)
    # and distribution sanity.
    refs = [(0, 0), (1, 0), (0, 1), (-1, 5), (12345, -678), (0x55, -0x21)]
    vals = hash01([a for a, _ in refs], [b for _, b in refs])
    in_range = bool(np.all((vals >= 0) & (vals < 1)))
    grid = hash01(np.arange(10000) % 100, np.arange(10000) // 100)
    spread = abs(float(grid.mean()) - 0.5) < 0.02 and float(grid.std()) > 0.25
    distinct = len(np.unique(np.round(vals, 9))) == len(refs)
    good = in_range and spread and distinct
    print(f"  [{'PASS' if good else 'FAIL'}] hash01: range ok, mean "
          f"{grid.mean():.3f}~0.5, std {grid.std():.3f}>0.25, refs distinct")
    ok &= good

    # 3 — no repetition: adjacent cells differ in grain offset and tone
    cols = np.arange(0, 200, dtype=np.int64)
    rows = np.zeros_like(cols)
    off_a = hash01(cols, rows)
    off_b = hash01(cols + 1, rows)
    tone_a = 0.94 + 0.12 * hash01(cols - 0x13, rows + 0x77)
    diff_frac = float(np.mean(np.abs(off_a - off_b) > 0.05))
    tone_var = float(np.std(tone_a))
    good = diff_frac > 0.85 and tone_var > 0.02
    print(f"  [{'PASS' if good else 'FAIL'}] no repetition: {diff_frac * 100:.0f}% of "
          f"neighbours differ in grain (>0.05), tone std {tone_var:.3f}")
    ok &= good

    # 4 — running bond: row stagger shifts cell boundaries between rows
    stags = hash01(np.arange(50, dtype=np.int64), np.full(50, 0x9E37, dtype=np.int64))
    good = float(np.std(stags)) > 0.2 and len(np.unique(np.round(stags, 6))) > 45
    print(f"  [{'PASS' if good else 'FAIL'}] running bond: stagger std {np.std(stags):.3f}, "
          f"{len(np.unique(np.round(stags, 6)))}/50 rows unique")
    ok &= good

    # 5 — seam geometry at fine footprint: borders grout, interiors material
    row = 3
    stag = float(hash01(np.array([row]), np.array([0x9E37]))[0])
    # exact cell border in x for col 7: sx = 8*RW  =>  rx = 8*RW - stag*RW
    border_x = np.array([8 * RW - stag * RW])
    center_x = np.array([(8 + 0.5) * RW - stag * RW])
    mid_y = np.array([(row + 0.5) * RH])
    fp = np.array([0.5])
    _, _, _, g_border = procedural_cells(border_x, mid_y, RW, RH, GF, TW, TH, fp)
    _, _, _, g_center = procedural_cells(center_x, mid_y, RW, RH, GF, TW, TH, fp)
    # measured seam half-width: walk from the border until material
    offs = np.linspace(0, 0.05, 200) * RW
    _, _, _, g_walk = procedural_cells(border_x + offs, np.full(200, mid_y[0]), RW, RH, GF, TW, TH, np.full(200, 0.5))
    measured_half = float(offs[np.argmax(g_walk < 0.5)]) / RW
    good = (
        float(g_border[0]) > 0.95
        and float(g_center[0]) < 0.05
        and abs(measured_half - GF / 2) < GF * 0.5
    )
    print(f"  [{'PASS' if good else 'FAIL'}] seam: border blend {g_border[0]:.2f}>0.95, "
          f"centre {g_center[0]:.2f}<0.05, half-width {measured_half:.4f}~{GF / 2:.4f}")
    ok &= good

    # 6 — AA: coarse footprint softens the seam (no hard alias at distance)
    _, _, _, g_soft = procedural_cells(border_x + offs, np.full(200, mid_y[0]), RW, RH, GF, TW, TH, np.full(200, 24.0))
    trans_soft = float(np.mean((g_soft > 0.1) & (g_soft < 0.9)))
    trans_hard = float(np.mean((g_walk > 0.1) & (g_walk < 0.9)))
    good = trans_soft > trans_hard
    print(f"  [{'PASS' if good else 'FAIL'}] anti-aliasing: transition share "
          f"{trans_soft:.2f} (coarse) > {trans_hard:.2f} (fine)")
    ok &= good

    # 7 — R2-4 pattern bonds: grid lays aligned, brick alternates half-cells
    mid_y0 = np.array([0.5 * RH])
    mid_y1 = np.array([1.5 * RH])
    probe_x = np.array([8 * RW])  # exact cell border when stagger = 0
    fp1 = np.array([0.5])
    _, _, _, gg0 = procedural_cells(probe_x, mid_y0, RW, RH, GF, TW, TH, fp1, pattern="grid")
    _, _, _, gg1 = procedural_cells(probe_x, mid_y1, RW, RH, GF, TW, TH, fp1, pattern="grid")
    _, _, _, gb1 = procedural_cells(probe_x + 0.5 * RW, mid_y1, RW, RH, GF, TW, TH, fp1, pattern="brick")
    good = float(gg0[0]) > 0.95 and float(gg1[0]) > 0.95 and float(gb1[0]) > 0.95
    print(f"  [{'PASS' if good else 'FAIL'}] R2-4 bonds: grid aligned across rows "
          f"({gg0[0]:.2f}/{gg1[0]:.2f}), brick offset half-cell ({gb1[0]:.2f})")
    ok &= good

    # 8 — R4-2 reflection: bright above-floor content reflects near the
    # contact line, fades with depth, dark content stays quiet
    Hh, Ww = 200, 60
    ys_r, xs_r = np.mgrid[100:200, 0:Ww]
    ys_r, xs_r = ys_r.ravel(), xs_r.ravel()
    base = np.zeros((Hh, Ww, 3), np.float64)
    base[60:100, :30] = 250.0   # bright window above floor, left half
    base[60:100, 30:] = 30.0    # dark wall, right half
    texel = np.full((len(xs_r), 3), 128.0)
    out = apply_reflection(texel, base, xs_r, ys_r, Hh, Ww)
    near_bright = out[(ys_r < 110) & (xs_r < 30), 0].mean()
    near_dark = out[(ys_r < 110) & (xs_r >= 30), 0].mean()
    far_bright = out[(ys_r > 180) & (xs_r < 30), 0].mean()
    good = near_bright > 138 and abs(near_dark - 128) < 2 and abs(far_bright - 128) < 4
    print(f"  [{'PASS' if good else 'FAIL'}] R4-2 reflection: near-window {near_bright:.0f}>138, "
          f"dark wall {near_dark:.0f}~128, far {far_bright:.0f}~128")
    ok &= good

    print("\n" + ("ALL R2-3 SIM CHECKS PASSED" if ok else "R2-3 SIM CHECKS FAILED"))
    return 0 if ok else 1


if __name__ == "__main__":
    raise SystemExit(main())