Function makePolygonsToPrevious

src/traces/scatter/plot.js:349–383

(prevFillsegments)

    };

    var makePolygonsToPrevious = function(prevFillsegments) {
        var polygons, i;
        if(!prevFillsegments || prevFillsegments.length === 0) {
            // if there are no fill segments of a previous trace, stretch the
            // polygon to the relevant axis
            polygons = new Array(fillsegments.length);
            for(i = 0; i < fillsegments.length; i++) {
                var pt0 = fillsegments[i][0].slice();
                var pt1 = fillsegments[i][fillsegments[i].length - 1].slice();

                pt0[fillAxisIndex] = pt1[fillAxisIndex] = fillAxisZero;

                var zeropoints = [pt1, pt0];
                var polypoints = zeropoints.concat(fillsegments[i]);
                polygons[i] = polygonTester(polypoints);
            }
        } else {
            // if there are more than one previous fill segment, the
            // way that fills work is to "self" fill all but the last segments
            // of the previous and then fill from the new trace to the last
            // segment of the previous.
            polygons = new Array(prevFillsegments.length - 1 + fillsegments.length);
            for(i = 0; i < prevFillsegments.length - 1; i++) {
                polygons[i] = polygonTester(prevFillsegments[i]);
            }

            var reversedPrevFillsegment = prevFillsegments[prevFillsegments.length - 1].slice();
            reversedPrevFillsegment.reverse();

            for(i = 0; i < fillsegments.length; i++) {
                polygons[prevFillsegments.length - 1 + i] = polygonTester(fillsegments[i].concat(reversedPrevFillsegment));
            }
        }
        return polygons;
    };

    // draw fills and create hover detection polygons
    if(segments.length) {