sparser data transfers

website/src/lib/data/example/index.ts

@@ -4,7 +4,8 @@
  * and the documentation. They are the ones that the engine computes for `example.gpx`, kept as
  * they are (see `example-data.ts`) so that the example does not need the engine.
  */
-import type { GlobalStatistics, SelectionStatistics } from '$lib/engine';
+import type { GlobalStatistics, SelectionPoint, SelectionStatistics } from '$lib/engine';
+import { intervalAt } from '$lib/engine/trackpoint-categories';
 import { exampleData as data } from '$lib/data/example/example-data';
 
 const length = data.lng.length;
@@ -46,6 +47,21 @@ async function slice(start: number, end: number): Promise<GlobalStatistics | und
     };
 }
 
+const slopeSegmentStarts = Uint32Array.from(data.slopeSegmentStarts);
+
+/** The data of the trackpoint at `index`, as the engine gives it (the example has no OSM data). */
+async function point(index: number): Promise<SelectionPoint | undefined> {
+    if (!(index >= 0 && index < length)) {
+        return undefined;
+    }
+    const segment = intervalAt(slopeSegmentStarts, index);
+    return {
+        time: data.timestamps[index],
+        slopeSegmentSlope: data.slopeSegmentSlopes[segment],
+        slopeSegmentDistance: data.slopeSegmentDistances[segment],
+    };
+}
+
 export const exampleStatistics: SelectionStatistics = {
     global: data.global,
     length,
@@ -54,10 +70,12 @@ export const exampleStatistics: SelectionStatistics = {
     lng: Float64Array.from(data.lng),
     lat: Float64Array.from(data.lat),
     ele: Float64Array.from(data.ele),
-    timestamps: BigInt64Array.from(data.timestamps, (time) => BigInt(time)),
     speed: Float64Array.from(data.speed),
     atemp: Float64Array.from(data.atemp),
-    slopeSegmentSlope: Float64Array.from(data.slopeSegmentSlope),
-    slopeSegmentDistance: Float64Array.from(data.slopeSegmentDistance),
+    slopeSegments: {
+        starts: slopeSegmentStarts,
+        slopes: Float64Array.from(data.slopeSegmentSlopes),
+    },
     slice,
+    point,
 };