src/classes/sigma.classes.edgequad.js
function(r) {
      var llc = this.lowerLeftCoor(r),
          lrc = this.lowerRightCoor(r, llc);

      return [
        {x: r.x1, y: r.y1},
        {x: r.x2, y: r.y2},
        {x: llc.x, y: llc.y},
        {x: lrc.x, y: lrc.y}
      ];
    }
function(r) {
      var llc = this.lowerLeftCoor(r),
          lrc = this.lowerRightCoor(r, llc);

      return [
        {x: r.x1, y: r.y1},
        {x: r.x2, y: r.y2},
        {x: llc.x, y: llc.y},
        {x: lrc.x, y: lrc.y}
      ];
    }
function ( r ) { var llc = this . lowerLeftCoor ( r ) , lrc = this . lowerRightCoor ( r , llc ) ; return [ { x : r . x1 , y : r . y1 } , { x : r . x2 , y : r . y2 } , { x : llc . x , y : llc . y } , { x : lrc . x , y : lrc . y } ] ; }
Get the coordinates of all the corners of a rectangle from its top point.

@param  {object} A rectangle defined by two points (x1, y1) and (x2, y2).
@return {array}  An array of the four corners' coordinates (x, y).
Get the coordinates of all the corners of a rectangle from its top point .