From ec236d146b663f5c1c35848a52d92b4e1bde9f32 Mon Sep 17 00:00:00 2001
From: Azgaar <azgaar.fmg@yandex.com>
Date: Fri, 6 Sep 2024 02:37:44 +0200
Subject: [PATCH] refactor: drawCoastline

---
 modules/renderers/draw-coastline.js | 34 ++++++++---------------------
 utils/pathUtils.js                  |  5 +++++
 2 files changed, 14 insertions(+), 25 deletions(-)

diff --git a/modules/renderers/draw-coastline.js b/modules/renderers/draw-coastline.js
index 43093f88..09ab07a3 100644
--- a/modules/renderers/draw-coastline.js
+++ b/modules/renderers/draw-coastline.js
@@ -15,20 +15,26 @@ function drawCoastline() {
   for (const i of cells.i) {
     const startFromEdge = !i && cells.h[i] >= 20;
     if (!startFromEdge && cells.t[i] !== -1 && cells.t[i] !== 1) continue; // non-edge cell
+
     const f = cells.f[i];
     if (used[f]) continue; // already connected
     if (features[f].type === "ocean") continue; // ocean cell
 
     const type = features[f].type === "lake" ? 1 : -1; // type value to search for
-    const start = findStart(i, type);
-    if (start === -1) continue; // cannot start here
-    let vchain = connectVertices(start, type);
+    const ofSameType = cellId => cells.t[cellId] === type || cellId >= n;
+
+    const startingVertex = findStart(i, type);
+    if (startingVertex === -1) continue; // cannot start here
+
+    let vchain = connectVertices({vertices, startingVertex, ofSameType});
     if (features[f].type === "lake") relax(vchain, 1.2);
     used[f] = 1;
+
     let points = clipPoly(
       vchain.map(v => vertices.p[v]),
       1
     );
+
     const area = d3.polygonArea(points); // area with lakes/islands
     if (area > 0 && features[f].type === "lake") {
       points = points.reverse();
@@ -81,28 +87,6 @@ function drawCoastline() {
     return index === -1 ? index : cells.v[i][index];
   }
 
-  // connect vertices to chain
-  function connectVertices(start, t) {
-    const chain = []; // vertices chain to form a path
-    for (let i = 0, current = start; i === 0 || (current !== start && i < 50000); i++) {
-      const prev = chain[chain.length - 1]; // previous vertex in chain
-      chain.push(current); // add current vertex to sequence
-      const c = vertices.c[current]; // cells adjacent to vertex
-      const v = vertices.v[current]; // neighboring vertices
-      const c0 = c[0] >= n || cells.t[c[0]] === t;
-      const c1 = c[1] >= n || cells.t[c[1]] === t;
-      const c2 = c[2] >= n || cells.t[c[2]] === t;
-      if (v[0] !== prev && c0 !== c1) current = v[0];
-      else if (v[1] !== prev && c1 !== c2) current = v[1];
-      else if (v[2] !== prev && c0 !== c2) current = v[2];
-      if (current === chain[chain.length - 1]) {
-        ERROR && console.error("Next vertex is not found");
-        break;
-      }
-    }
-    return chain;
-  }
-
   // move vertices that are too close to already added ones
   function relax(vchain, r) {
     const p = vertices.p,
diff --git a/utils/pathUtils.js b/utils/pathUtils.js
index 34f9ee14..83101f60 100644
--- a/utils/pathUtils.js
+++ b/utils/pathUtils.js
@@ -159,6 +159,11 @@ function connectVertices({vertices, startingVertex, ofSameType, addToChecked, cl
     else if (v2 !== previous && c2 !== c3) next = v2;
     else if (v3 !== previous && c1 !== c3) next = v3;
 
+    if (!vertices.c[next]) {
+      ERROR && console.error("ConnectVertices: next vertex is out of bounds");
+      break;
+    }
+
     if (next === current) {
       ERROR && console.error("ConnectVertices: next vertex is not found");
       break;