Function toggleRotateMode

js/main.js:2393–2421

(active)

  if (!mesh) return;
  _raycaster.setFromCamera(_canvasNDC(e), getCamera());
  const hits = _raycaster.intersectObject(mesh);
  const hit = getFrontFaceHit(hits, mesh);
  if (!hit) return;

  // Get the face normal (mesh has identity transform)
  const faceNormal = hit.face.normal.clone().normalize();

  // Compute quaternion that rotates faceNormal to -Z (face down on print bed)
  const targetDir = new THREE.Vector3(0, 0, -1);
  const quat = new THREE.Quaternion().setFromUnitVectors(faceNormal, targetDir);

  // Apply rotation to all vertex positions
  const pos = currentGeometry.attributes.position.array;
  const v = new THREE.Vector3();
  for (let i = 0; i < pos.length; i += 3) {
    v.set(pos[i], pos[i + 1], pos[i + 2]);
    v.applyQuaternion(quat);
    pos[i]     = v.x;
    pos[i + 1] = v.y;
    pos[i + 2] = v.z;
  }

  // Fold the rotation into the pose transform (undone again on export).
  currentPoseRot.premultiply(quat).normalize();
  currentPoseTrans.applyQuaternion(quat);

  // Re-center geometry
  currentGeometry.computeBoundingBox();
  const center = new THREE.Vector3();
  currentGeometry.boundingBox.getCenter(center);
  currentGeometry.translate(-center.x, -center.y, -center.z);
  currentPoseTrans.sub(center);