Hi @ScottDavis3. With your help, I was able to get a working solution. Thank you! Seems this would be built into the ArcGIS API for JavaScript?!
I have made a couple of changes to Scott's code. Most notably, I had to change get_length() to geodesicLength() in the geometryEngine class because I couldn't find get_length().
The code below utilizes the ArcGIS for JavaScript 3.x version.
function getPolylineMidPoint(polyline) {
const path = polyline.paths[0];
const length = GeometryEngine.geodesicLength(polyline, "feet"); // esri.geometry.geometryEngine
const middleLength = length / 2;
var currentDistance = 0;
var beforeIndex = 0;
var startPoint = polyline.getPoint(0, 0);
for (let i = 1; i < path.length - 1; i++) {
var nextPoint = polyline.getPoint(0, i);
var d = GeometryEngine.distance(startPoint, nextPoint, "feet");
if (currentDistance + d < middleLength) {
currentDistance += d;
startPoint = nextPoint;
} else {
beforeIndex = (i === 1) ? 0 : i;
break;
}
}
startPoint = polyline.getPoint(0, beforeIndex);
const endPoint = polyline.getPoint(0, beforeIndex + 1);
const x = (startPoint.x + endPoint.x) / 2;
const y = (startPoint.y + endPoint.y) / 2;
const midPoint = new Point({ x, y, spatialReference: { wkid: polyline.spatialReference.wkid } }); // esri.geometry.Point
return midPoint;
};
function doTest () {
const query = new Query(); // esri.tasks.Query
query.where = "Type='Tunnel'";
self._someLayer.queryFeatures(query,
(fs) => {
const features = fs.features;
const midPoint = getPolylineMidPoint(features[0].geometry); // utilizing the midpoint function
const location = webMercatorUtils.webMercatorToGeographic(midPoint); // esri.geometry.webMercatorUtils
const symbol = new SimpleMarkerSymbol( // "esri.symbols.SimpleMarkerSymbol"
SimpleMarkerSymbol.STYLE_CIRCLE,
15,
new SimpleLineSymbol( // "esri.symbols.SimpleLineSymbol"
SimpleLineSymbol.STYLE_SOLID,
new Color([0, 0, 255, 0.5]),
8
),
new Color([0, 0, 255]) // esri.Color
);
const graphic = new Graphic(location, symbol); // esri.Graphic
self.map.graphics.add(graphic);
},
(err) => {
console.log("Error: " + err);
});
};
