code: function (a, b, bounds, useLastCode) {
  		var codeA = useLastCode ? this._lastCode : this._getBitCode(a, bounds),
  		    codeB = this._getBitCode(b, bounds),
  
  		    codeOut, p, newCode;
  
  		// save 2nd code to avoid calculating it on the next segment
  		this._lastCode = codeB;
  
  		while (true) {
  			// if a,b is inside the clip window (trivial accept)
  			if (!(codeA | codeB)) {
  				return [a, b];
  			// if a,b is outside the clip window (trivial reject)
  			} else if (codeA & codeB) {
  				return false;
  			// other cases
  			} else {
  				codeOut = codeA || codeB;
  				p = this._getEdgeIntersection(a, b, codeOut, bounds);
  				newCode = this._getBitCode(p, bounds);
  
  				if (codeOut === codeA) {
  					a = p;
  					codeA = newCode;
  				} else {
  					b = p;
  					codeB = newCode;
  				}
  			}
  		}
  	}
docs: Cohen-Sutherland line clipping algorithm. Used to avoid rendering parts of a polyline that are not currently visible.