Add survey markers layer

layers/survey-markers/index.js

@@ -0,0 +1,39 @@
+import VectorLayer from 'ol/layer/Vector';
+import {Vector as VectorSource} from 'ol/source.js';
+import GeoJSON from 'ol/format/GeoJSON.js';
+
+import {Style} from 'ol/style.js';
+import Icon from 'ol/style/Icon.js';
+
+import pin from './pin.svg?url';
+import states from './states.js';
+
+let survey_markers = {
+    name: "National Geodetic Survey Markers",
+    details: `These are extremely large, and loading too many at once may crash your browser.<br><a href="#" onclick="this.closest('details').querySelectorAll('ul li input').forEach(e => e.checked || e.click()); return false;">Enable All (will <i>definitely</i> crash your browser)</a>`,
+    layers: [],
+};
+
+for (let [state, url] of Object.entries(states)) {
+    const vectorLayer = new VectorLayer({
+        source: new VectorSource({
+            url: url,
+            format: new GeoJSON,
+        }),
+        style: new Style({
+            image: new Icon({
+                anchor: [0.5, 1],
+                src: pin,
+            }),
+        }),
+    });
+
+    survey_markers.layers.push({
+        name: state,
+        layer: vectorLayer,
+    });
+}
+
+survey_markers.layers.sort((a, b) => a.name > b.name ? 1 : -1); // Names are always unique
+
+export default survey_markers;