From cd875f802527f182d5bb9c17a8c18ab998923dc8 Mon Sep 17 00:00:00 2001
From: cha0s <git@cha0s.io>
Date: Sun, 7 Jul 2024 17:31:27 -0500
Subject: [PATCH] feat: tile hulls

---
 app/ecs-components/index.js            |  2 +-
 app/ecs-components/tile-layers.js      | 62 ++++++++++++++++++++++++++
 app/ecs-components/tile-layers.test.js | 45 +++++++++++++++++++
 3 files changed, 108 insertions(+), 1 deletion(-)
 create mode 100644 app/ecs-components/tile-layers.test.js

diff --git a/app/ecs-components/index.js b/app/ecs-components/index.js
index 91de02e..d077722 100644
--- a/app/ecs-components/index.js
+++ b/app/ecs-components/index.js
@@ -1,7 +1,7 @@
 import gather from '@/util/gather.js';
 
 const Gathered = gather(
-  import.meta.glob('./*.js', {eager: true, import: 'default'}),
+  import.meta.glob(['./*.js', '!./*.test.js'], {eager: true, import: 'default'}),
 );
 
 const Components = {};
diff --git a/app/ecs-components/tile-layers.js b/app/ecs-components/tile-layers.js
index 4cde1bf..9235d92 100644
--- a/app/ecs-components/tile-layers.js
+++ b/app/ecs-components/tile-layers.js
@@ -1,4 +1,5 @@
 import Component from '@/ecs/component.js';
+import {floodwalk2D, ortho, removeCollinear} from '@/util/math.js';
 
 import vector2d from './helpers/vector-2d';
 
@@ -14,6 +15,67 @@ class LayerProxy {
   get data() {
     return this.layer.data;
   }
+  get hulls() {
+    const {data, area, tileSize} = this;
+    const hulls = [];
+    const seen = {};
+    const n = data.length;
+    const {x: w, y: h} = area;
+    let x = 0;
+    let y = 0;
+    for (let i = 0; i < n; ++i) {
+      if (data[i]) {
+        if (!seen[i]) {
+          const indices = floodwalk2D(new Set([data[i]]), data, {x, y, w, h});
+          if (indices.size > 0) {
+            const pointHash = Object.create(null);
+            const points = [];
+            const seePoint = ({x, y}) => {
+              if (pointHash[y]?.[x]) {
+                return false;
+              }
+              if (!pointHash[y]) {
+                pointHash[y] = Object.create({});
+              }
+              return pointHash[y][x] = true;
+            };
+            for (const index of indices) {
+              seen[index] = true;
+              const op = {
+                x: tileSize.x * (index % area.x),
+                y: tileSize.y * (Math.floor(index / area.x)),
+              };
+              let p;
+              const tsq = {x: tileSize.x / 4, y: tileSize.y / 4};
+              p = {x: op.x + tsq.x, y: op.y + tsq.y};
+              if (seePoint(p)) {
+                points.push(p);
+              }
+              p = {x: op.x + tileSize.x - tsq.x, y: op.y + tsq.y};
+              if (seePoint(p)) {
+                points.push(p);
+              }
+              p = {x: op.x + tileSize.x - tsq.x, y: op.y + tileSize.y - tsq.y};
+              if (seePoint(p)) {
+                points.push(p);
+              }
+              p = {x: op.x + tsq.x, y: op.y + tileSize.y - tsq.y};
+              if (seePoint(p)) {
+                points.push(p);
+              }
+            }
+            hulls.push(removeCollinear(ortho(points, {x: tileSize.x / 2, y: tileSize.y / 2})));
+          }
+        }
+      }
+      x += 1;
+      if (x === w) {
+        x -= w;
+        y += 1;
+      }
+    }
+    return hulls;
+  }
   get layer() {
     return this.instance.layers[this.index];
   }
diff --git a/app/ecs-components/tile-layers.test.js b/app/ecs-components/tile-layers.test.js
new file mode 100644
index 0000000..064542e
--- /dev/null
+++ b/app/ecs-components/tile-layers.test.js
@@ -0,0 +1,45 @@
+import {expect, test} from 'vitest';
+
+import Ecs from '@/ecs/ecs.js';
+
+import TileLayers from './tile-layers.js';
+
+test('creates hulls', async () => {
+  const Component = new TileLayers(new Ecs());
+  const data = Array(64).fill(0);
+  data[9] = 1;
+  data[10] = 1;
+  data[17] = 1;
+  data[18] = 1;
+  const layers = await Component.create(1, {
+    layers: [
+      {
+        area: {x: 8, y: 8},
+        data,
+        source: '',
+        tileSize: {x: 16, y: 16},
+      }
+    ],
+  });
+  expect(layers.layer(0).hulls)
+    .to.deep.equal([
+      [
+        {x: 20, y: 20},
+        {x: 44, y: 20},
+        {x: 44, y: 44},
+        {x: 20, y: 44},
+      ]
+    ]);
+  data[11] = 1;
+  expect(layers.layer(0).hulls)
+    .to.deep.equal([
+      [
+        {x: 20, y: 20},
+        {x: 60, y: 20},
+        {x: 60, y: 28},
+        {x: 44, y: 28},
+        {x: 44, y: 44},
+        {x: 20, y: 44},
+      ]
+    ]);
+});