code: function rotateZ(out, a, b, c){
      var bx = b[0]
      var by = b[1]
  
      //Translate point to the origin
      var px = a[0] - bx
      var py = a[1] - by
    
      var sc = Math.sin(c)
      var cc = Math.cos(c)
  
      // perform rotation and translate to correct position
      out[0] = bx + px * cc - py * sc
      out[1] = by + px * sc + py * cc
      out[2] = a[2]
    
      return out
  }
docs: Rotate a 3D vector around the z-axis
  @param {vec3} out The receiving vec3
  @param {vec3} a The vec3 point to rotate
  @param {vec3} b The origin of the rotation
  @param {Number} c The angle of rotation
  @returns {vec3} out