updatePoints = (line, conn, bb, altBB, pre, altPre) => {
      const srcX = altBB.x + altBB.width / 2
      const srcY = altBB.y + altBB.height / 2

      const pt = getBBintersect(srcX, srcY, bb, getOffset(pre, line))
      setPoint(line, conn.is_start ? 0 : 'end', pt.x, pt.y, true)

      const pt2 = getBBintersect(pt.x, pt.y, altBB, getOffset(altPre, line))
      setPoint(line, conn.is_start ? 'end' : 0, pt2.x, pt2.y, true)
    }
@param {Float} diffX
@param {Float} diffY
@returns {void}