How to use the raphael.fullfill function in raphael

var y1 = (sourceBox.y + sourceBox.y2)/2;
        var x2 = (targetBox.x + targetBox.x2)/2 - target.direction * targetBox.width/2;
        var y2 = (targetBox.y + targetBox.y2)/2;
        var k1 = 0.8;
        var k2 = 0.2;
        var pathPoints = {
            x1: x1,
            y1: y1,
            x2: x2,
            y2: y2,
            x3: x2 - k1 * (x2 - x1),
            y3: y2 - k2 * (y2 - y1)

        };

        var edgePath = paper.path(Raphael.fullfill("M{x1},{y1}Q{x3},{y3},{x2},{y2}",pathPoints));
        edgePath.attr({
            'stroke': '#999',
            'stroke-width': 2
        });
        edgePath.toBack();
        shape = paper.set().push(edgePath);

        //如果target存在connectFather,重画这条边
        if(edge.shape){
            edge.shape[0].remove();
            edge.shape = shape;
        }{
            edge.shape = shape;
        }
    }

var xc = (xs + xt1)/2;
        var yc = ys;


        var shortPath = paper.path(Raphael.fullfill("M{x1},{y1}L{x2},{y2}",{
            x1: xs, y1: ys, x2: xc, y2: yc
        }));
        var connectPath = paper.path(Raphael.fullfill("M{x1},{y1}L{x2},{y2}",{
            x1: xc, y1: yc, x2: xt1, y2: yt1
        })).attr({
            'stroke': '#999',
            'stroke-width': 2
        });
        var targetUnderPath = paper.path(Raphael.fullfill("M{x1},{y1}L{x2},{y2}",{
            x1: xt1, y1: yt1, x2: xt2, y2: yt2
        }));

        shape = paper.set().push(shortPath).push(connectPath).push(targetUnderPath);

        //如果target存在connectFather,重画这条边
        if(edge.shape){
            edge.shape[0].remove();
            edge.shape[1].remove();
            edge.shape[2].remove();
            edge.shape = shape;
        }{
            edge.shape = shape;
        }
    }