"""Door robot arm: every link of the arm as surface points in its own frame (origin on its joint, unscaled), for the
fit (2026-10-18, scale-up). Reads this model's file; writes build/arm_points.npz (per link: points, joint, parent).

    blender -b --factory-startup --python build/dra_arm_points.py -- <DoorRobotArm.blend>
"""
import os
import sys
import math
import random
import numpy as np
import bpy

HERE = os.path.dirname(os.path.abspath(__file__))
sys.path.insert(0, HERE)
args = sys.argv[sys.argv.index("--") + 1:]
bpy.ops.wm.open_mainfile(filepath=args[0], load_ui=False)
import dra_rigdata as rd      # noqa: E402

STEP = 0.035
rng = random.Random(5)
out = {}
for spec in rd.LINKS:
    me = bpy.data.meshes.get(rd.mesh_name(spec["name"]))
    if me is None:
        continue
    me.calc_loop_triangles()
    V = [v.co.copy() for v in me.vertices]
    lay = me.attributes.get('part')
    dec = list(me.get("decals", []))
    pts = [tuple(v) for v in V]
    for lt in me.loop_triangles:
        if lay is not None and dec:
            pv = lay.data[lt.polygon_index].value
            if 0 <= pv < len(dec) and dec[pv]:
                continue
        a, b, c = (V[i] for i in lt.vertices)
        area = (b - a).cross(c - a).length / 2
        n = int(area / (STEP * STEP))
        for _ in range(n):
            r1, r2 = rng.random(), rng.random()
            if r1 + r2 > 1:
                r1, r2 = 1 - r1, 1 - r2
            p = a + (b - a) * r1 + (c - a) * r2
            pts.append((p.x, p.y, p.z))
    P = np.array(pts, np.float32)
    key = spec["name"].replace(" ", "_")
    out["pts__" + key] = P
    out["joint__" + key] = np.array(spec["joint"], np.float64)
    out["parent__" + key] = np.array(spec["parent"] or "")
    print("[ap] %-26s %6d points" % (spec["name"], len(P)), flush=True)
np.savez_compressed(os.path.join(HERE, "arm_points.npz"), **out)
print("[ap] written", flush=True)