function prepareCustom(coordSys) {
	        var radiusAxis = coordSys.getRadiusAxis();
	        var angleAxis = coordSys.getAngleAxis();
	        var radius = radiusAxis.getExtent();
	        radius[0] > radius[1] && radius.reverse();

	        return {
	            coordSys: {
	                type: 'polar',
	                cx: coordSys.cx,
	                cy: coordSys.cy,
	                r: radius[1],
	                r0: radius[0]
	            },
	            api: {
	                coord: zrUtil.bind(function (data) {
	                    var radius = radiusAxis.dataToRadius(data[0]);
	                    var angle = angleAxis.dataToAngle(data[1]);
	                    var coord = coordSys.coordToPoint([radius, angle]);
	                    coord.push(radius, angle * Math.PI / 180);
	                    return coord;
	                }),
	                size: zrUtil.bind(dataToCoordSize, coordSys)
	            }
	        };
	    }
@private
@type {module:echarts/graphic/GraphicModel}