message: improved unitcell bounding sphere (added extrema)
diff: @@ -68,11 +68,22 @@ function getUnitcellMesh(data: UnitcellData, props: UnitcellProps, mesh?: Mesh)
  const cpD = Vec3.create(0, 1, 1)
  Vec3.transformMat4(cpD, Vec3.add(cpD, cpD, tmpRef), fromFractional)
  + const cpE = Vec3.create(0, 0, 1)
  + Vec3.transformMat4(cpE, Vec3.add(cpE, cpE, tmpRef), fromFractional)
  + const cpF = Vec3.create(1, 0, 1)
  + Vec3.transformMat4(cpF, Vec3.add(cpF, cpF, tmpRef), fromFractional)
  + const cpG = Vec3.create(1, 1, 0)
  + Vec3.transformMat4(cpG, Vec3.add(cpG, cpG, tmpRef), fromFractional)
  + const cpH = Vec3.create(0, 1, 0)
  + Vec3.transformMat4(cpH, Vec3.add(cpH, cpH, tmpRef), fromFractional)
  +
  const center = Vec3()
  Vec3.add(center, cpA, cpB)
  Vec3.scale(center, center, 0.5)
  const d = Math.max(Vec3.distance(cpA, cpB), Vec3.distance(cpC, cpD))
  - const sphere = Sphere3D.create(center, d / 2 + radius)
  + const sphere = Sphere3D.create(center, d / 2)
  + Sphere3D.setExtrema(sphere, [cpA, cpB, cpC, cpD, cpE, cpF, cpG, cpH])
  + Sphere3D.expand(sphere, sphere, radius)
  const m = MeshBuilder.getMesh(state)
  m.setBoundingSphere(sphere)
  