From b1f41d797489fbf977196c09fab01f71aaec7f6b Mon Sep 17 00:00:00 2001
From: ajuvercr <arthur.vercruysse@outlook.com>
Date: Mon, 20 Apr 2020 10:04:24 +0200
Subject: [PATCH] better handle outliers in voronoi

---
 frontend/www/src/voronoi/voronoi.ts | 84 +++++++++++++++++++++++++----
 1 file changed, 73 insertions(+), 11 deletions(-)

diff --git a/frontend/www/src/voronoi/voronoi.ts b/frontend/www/src/voronoi/voronoi.ts
index c94959f..796e151 100644
--- a/frontend/www/src/voronoi/voronoi.ts
+++ b/frontend/www/src/voronoi/voronoi.ts
@@ -5,10 +5,60 @@ import { DefaultRenderable } from "../webgl/renderer";
 import { IndexBuffer, VertexBuffer } from "../webgl/buffer";
 import { VertexBufferLayout, VertexArray } from "../webgl/vertexBufferLayout";
 
+function arcctg(x: number): number { return Math.PI / 2 - Math.atan(x); }
+
 function to_key(p: Point): string {
     return [p.x, p.y] + "";
 }
 
+function round_point(center: Point, point: Point, amount_fn = (b: number) => 0.7): Point {
+    const d = dist(center, point, true);
+    console.log("f:", amount_fn(d));
+    const x = center.x + amount_fn(d) * (point.x - center.x);
+    const y = center.y + amount_fn(d) * (point.y - center.y);
+    return { 'x': x, 'y': y };
+}
+
+function median_point(c: Point, p: Point, n: Point, d = 0.1): number[] {
+    const dd = 1.0 - 2 * d;
+    return [
+        dd * c.x + d * p.x + d * n.x,
+        dd * c.y + d * p.y + d * n.y,
+    ]
+}
+
+function build_point_map(es: Voronoi.HalfEdge[]): (point: Point) => Point {
+    const mean = es.map(e => dist(e.getStartpoint(), e.getEndpoint())).reduce((a, b) => a + b, 0) / es.length;
+    const map = {};
+
+    for (let edge of es) {
+        const start = edge.getStartpoint();
+        const end = edge.getEndpoint();
+
+        if (dist(start, end) < 0.1 * mean) {    // These points have to be merged
+            const middle = { 'x': (start.x + end.x) / 2, 'y': (start.y + end.y) / 2 };
+            map[to_key(start)] = middle;
+            map[to_key(end)] = middle;
+        }
+    }
+
+    return (p) => map[to_key(p)] || p;
+}
+
+function get_round_fn(dist_mean: number, amount = 0.7): (d: number) => number {
+    return (d) => {
+        console.log(arcctg(d - dist_mean));
+        return arcctg((d - dist_mean) * 3) / Math.PI / 2 + 0.5
+    }
+}
+
+function dist(a: Point, b: Point, norm = false): number {
+    const dx = a.x - b.x;
+    const dy = a.y - b.y;
+    if (norm) return Math.sqrt(dx * dx + dy * dy);
+    return dx * dx + dy * dy;
+}
+
 export class VoronoiBuilder {
     inner: DefaultRenderable;
 
@@ -18,10 +68,10 @@ export class VoronoiBuilder {
     constructor(gl: WebGLRenderingContext, shader: Shader, planets: Point[], bbox: BBox) {
         const voronoi = new Voronoi();
 
-        const own_map = {};
-        planets.forEach((p, i)=>own_map[to_key(p)] = i);
-
         // This voronoi sorts the planets, then owners don't align anymore
+        const own_map = {};
+        planets.forEach((p, i) => own_map[to_key(p)] = i);
+
         this.vor = voronoi.compute(planets, bbox);
 
         const a_pos = [];
@@ -33,27 +83,39 @@ export class VoronoiBuilder {
         for (let i = 0; i < this.vor.cells.length; i++) {
             const cell = this.vor.cells[i];
             const planetId = own_map[to_key(cell.site)];
+            const point_map = build_point_map(cell.halfedges);
 
             const centerId = vertCount++;
+
             a_pos.push(cell.site.x, cell.site.y);
             a_own.push(planetId);
 
+            const dist_mean = cell.halfedges.map(e => dist(cell.site, e.getStartpoint(), true)).reduce((a, b) => a + b, 0) / cell.halfedges.length;
+            const round_fn = get_round_fn(dist_mean);
+
             for (let edge of cell.halfedges) {
-                const start = edge.getStartpoint();
-                const end = edge.getEndpoint();
-                const center = {'x': (start.x + end.x) / 2, 'y': (start.y + end.y) / 2};
+                let start = point_map(edge.getStartpoint());
+                let end = point_map(edge.getEndpoint());
+                let center = { 'x': (start.x + end.x) / 2, 'y': (start.y + end.y) / 2 };
+
+                if (to_key(start) == to_key(end)) continue;
+
+                start = round_point(cell.site, start, round_fn);
+                center = round_point(cell.site, center, round_fn);
+                end = round_point(cell.site, end, round_fn);
 
                 ids.push(centerId);
                 ids.push(vertCount++);
                 a_pos.push(start.x, start.y);
                 a_own.push(-1);
 
-                // ids.push(vertCount++);
-                // a_pos.push(center.x, center.y);
-                // a_own.push(planetId);
+                ids.push(vertCount++);
+                a_pos.push(center.x, center.y);
+                a_own.push(-1);
+
+                ids.push(centerId);
+                ids.push(vertCount - 1);
 
-                // ids.push(centerId);
-                // ids.push(vertCount-1);
                 ids.push(vertCount++);
                 a_pos.push(end.x, end.y);
                 a_own.push(-1);