/* 共享状态根：渲染器/场景/相机/灯光/栅格 + 关节链 + 网格构建 + 按需渲染标志 */
const TL = {}; for (const t of TRAVEL) TL[t.axis] = t;
const V3 = THREE.Vector3;
const VC = p => [p[0], p[2], -p[1]];           // CAD (x,y,z) -> viewer (x,z,-y); must precede use
const cv = document.getElementById('cv');
const rend = new THREE.WebGLRenderer({canvas:cv, antialias:true, preserveDrawingBuffer:true});
rend.setPixelRatio(Math.min(window.devicePixelRatio || 1, 1.5));
const scene = new THREE.Scene();
scene.background = new THREE.Color(0x0d0f13);
const cam = new THREE.PerspectiveCamera(38, 1, 1, 6000);
scene.add(new THREE.HemisphereLight(0xcfe4ff, 0x22262e, 1.15));
const key = new THREE.DirectionalLight(0xffffff, 1.5); key.position.set(420, 620, 520); scene.add(key);
const key2 = new THREE.DirectionalLight(0x9dc4ff, .7); key2.position.set(-520, 300, -420); scene.add(key2);
const grid = new THREE.GridHelper(600, 30, 0x2b323e, 0x1b2028); grid.position.y = -0.5; scene.add(grid);

let needRender = true;
function requestRender() { needRender = true; }

/* ---- kinematic groups: nested pivot matrices, serial chain ---- */
const ROOT = new THREE.Object3D(); scene.add(ROOT);
const JG = {root: ROOT};
const JO = DATA.joints;
const parentOf = {J1:'root', J2:'J1', J3:'J2', J4:'J3', J5:'J4', J6:'J5'};
const ang = {J1:0, J2:0, J3:0, J4:0, J5:0, J6:0};
for (const j of JO) {
  const g = new THREE.Object3D(); g.matrixAutoUpdate = false;
  JG[j.id] = g; JG[parentOf[j.id]].add(g);
}
/* 轴心 P / 轴向 D 只与 CAD 参数有关：预计算一次；矩阵合成改用 3 个共享实例。
   旧版每次调用新建 2 个 Vector3 + 3 个 Matrix4（一次关节写入 = 6 次调用 = 30 个临时对象），
   动画与实时追踪高频触发时纯属垃圾。数学与原式逐位相同：T(P)·R(D,θ)·T(−P)。 */
const JP = {}, JD = {};
for (const j of JO) { JP[j.id] = new V3(...VC(j.rear)); JD[j.id] = new V3(...VC(j.d)).normalize(); }
const _jmT = new THREE.Matrix4(), _jmR = new THREE.Matrix4(), _jmTi = new THREE.Matrix4();
function applyJoint(id) {
  // geometry vertices were built in the viewer frame (x, z, -y), so the pivot point and the
  // axis must go through the same swap - using raw CAD coords rotates about the wrong line
  const P = JP[id], D = JD[id]; if (!P) return;
  const a = (ang[id] || 0) * Math.PI / 180;
  const m = _jmT.makeTranslation(P.x, P.y, P.z)
    .multiply(_jmR.makeRotationAxis(D, a))
    .multiply(_jmTi.makeTranslation(-P.x, -P.y, -P.z));
  JG[id].matrix.copy(m);
  JG[id].matrixWorldNeedsUpdate = true;
  if (window.updateHarnessBridges && window.isHarnessVisible && window.isHarnessVisible()) {
    updateHarnessBridges();
  }
  requestRender();
}

/* ---- meshes ---- */
const meshes = [], byName = {};
let expl = 0;
for (const p of DATA.parts) {
  const geo = new THREE.BufferGeometry();
  const pos = new Float32Array(p.v.length * 3);
  for (let i = 0; i < p.v.length; i++) { pos[i*3] = p.v[i][0]; pos[i*3+1] = p.v[i][2]; pos[i*3+2] = -p.v[i][1]; }
  p.triCount = p.t ? p.t.length : 0;
  p.vertCount = p.v.length;
  /* 外形三围：模型坐标系 X×Y×Z 包围盒（装配零位、打印朝向 Z=高），悬停面板显示用 */
  { let x0=1e9,y0=1e9,z0=1e9,x1=-1e9,y1=-1e9,z1=-1e9;
    for (let i = 0; i < p.v.length; i++) { const a = p.v[i];
      if (a[0]<x0)x0=a[0]; if (a[0]>x1)x1=a[0];
      if (a[1]<y0)y0=a[1]; if (a[1]>y1)y1=a[1];
      if (a[2]<z0)z0=a[2]; if (a[2]>z1)z1=a[2]; }
    p.dims = [x1-x0, y1-y0, z1-z0]; }
  const isEnv = p.name.slice(0, 4) === 'ENV_';          // 可达包络：运动学边界，不随关节动
  /* 索引按顶点数降位：单件 ≤65535 顶点时 Uint16 合法（92 件实测最大 47483），
     索引内存与上传带宽减半；超大件保留 Uint32 兜底。 */
  const IDX16 = p.v.length <= 65535;
  if (p.kind === 'line') {                              // 经纬线：LineSegments，无三角面
    const sIdx = IDX16 ? new Uint16Array(p.s) : new Uint32Array(p.s);
    geo.setAttribute('position', new THREE.BufferAttribute(pos, 3));
    geo.setIndex(new THREE.BufferAttribute(sIdx, 1));
    geo.computeBoundingSphere(); geo.computeBoundingBox();
    const lm = new THREE.LineBasicMaterial({color: p.color, transparent: true, opacity: 0.8});
    const ls = new THREE.LineSegments(geo, lm);
    ls.userData = p;
    ls.position.set(p.ex[0], p.ex[2], -p.ex[1]);
    ls.base = ls.position.clone();
    ls.visible = !isEnv;                               // 包络默认隐藏，走开关显示
    JG[p.grp || 'root'].add(ls);
    meshes.push(ls); byName[p.name] = ls;
    delete p.v; delete p.s;
    continue;
  }
  const idx = IDX16 ? new Uint16Array(p.t.length * 3) : new Uint32Array(p.t.length * 3);
  // the vertex map (x,y,z)->(x,z,-y) has determinant +1, so triangle winding must be kept
  // as-is; swapping two indices here inverted every face and made the normals point inward
  for (let i = 0; i < p.t.length; i++) { idx[i*3] = p.t[i][0]; idx[i*3+1] = p.t[i][1]; idx[i*3+2] = p.t[i][2]; }
  geo.setAttribute('position', new THREE.BufferAttribute(pos, 3));
  geo.setIndex(new THREE.BufferAttribute(idx, 1));
  geo.computeVertexNormals();
  geo.computeBoundingSphere();
  geo.computeBoundingBox();
  delete p.v;
  delete p.t;
  const isMo = !p.printed && p.name[0] === 'M';
  const isScr = !!p.screw;                              // 紧固件（螺钉）：金属亮色，可被 BOM 行高亮
  const mat = new THREE.MeshStandardMaterial({
    color: p.color, metalness: isScr ? .78 : (isMo ? .55 : .05),
    roughness: isScr ? .30 : (isMo ? .42 : .78),
    transparent: isEnv, opacity: isEnv ? .06 : 1,
    depthWrite: !isEnv,
    flatShading: false, side: isEnv ? THREE.DoubleSide : THREE.FrontSide});
  const ms = new THREE.Mesh(geo, mat);
  ms.userData = p;
  ms.position.set(p.ex[0], p.ex[2], -p.ex[1]);
  ms.base = ms.position.clone();
  ms.zero = [0,0,0];
  if (isEnv) ms.visible = false;                        // 包络默认隐藏，走开关显示
  JG[p.grp || 'root'].add(ms);
  meshes.push(ms); byName[p.name] = ms;
}