From 3b1ba45a883f45d746c236bce1750b2e198bc3e6 Mon Sep 17 00:00:00 2001
From: Val Erastov <xibyte@gmail.com>
Date: Wed, 23 Nov 2016 19:22:23 -0800
Subject: [PATCH] mesh utils

---
 web/app/3d/mesh.js | 82 ++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 82 insertions(+)
 create mode 100644 web/app/3d/mesh.js

diff --git a/web/app/3d/mesh.js b/web/app/3d/mesh.js
new file mode 100644
index 00000000..4d153379
--- /dev/null
+++ b/web/app/3d/mesh.js
@@ -0,0 +1,82 @@
+import Vector from '../math/vector'
+import * as cad_utils from './cad-utils'
+import * as math from '../math/math'
+import {Matrix3, AXIS, ORIGIN} from '../math/l3space'
+import {HashTable} from '../utils/hashmap'
+
+export function MeshFace() {
+  this.polygons = [];
+}
+
+export function MeshPolygon(id, normal, w, points) {
+  this.id = id;
+  this.normal = normal;
+  this.w = w;
+  this.points = points;
+  this.neighbors = [];
+}
+
+export function Mesh(edges) {
+  this.edges = edges;
+  this.faces = [];
+  this.getEdgeInfo = function(point1, point2) {
+    return edges.get(arguments)
+  }
+}
+
+Mesh.fromPolygons = function(polygons, smoothAngle) {
+  const edges = HashTable.forEdge();
+  
+  let counter = 0;
+  const allPolygons = [];
+  function index(polygon) {
+    if (polygon.length < 3) {
+      console.warn('invalid polygon ' + polygon);
+      return;
+    }
+    const normal = cad_utils.normalOfCCWSeq(polygon);
+    const w = normal.dot(polygon[0]);
+
+    const polygonInfo = new MeshPolygon(counter++, normal, w, polygon);
+    
+    allPolygons.push(polygonInfo);
+    
+    for (let p = polygon.length - 1, q = 0; q < polygon.length; p = q ++) {
+      var edgeKey = [polygon[p], polygon[q]];
+      let edgeInfo = edges.get(edgeKey);
+      if (edgeInfo == null) {
+        edges.put(edgeKey, [polygonInfo])
+      } else {
+        let other = edgeInfo[0];
+        other.neighbors.push(polygonInfo);
+        polygonInfo.neighbors.push(other);
+        edgeInfo.push(polygonInfo);
+      }
+    }
+  }
+
+  const visited = {};
+  function mergePolygons(tr, meshFace) {
+    if (visited[tr.id]) {
+      return;
+    }
+    visited[tr.id] = true;
+    meshFace.polygons.push(tr);
+    for (let nb of tr.neighbors) {
+      if (Math.acos(nb.normal.dot(tr.normal)) < smoothAngle) {
+        mergePolygons(nb, meshFace)
+      }
+    }
+  }
+  polygons.forEach(p => index(p));
+  const mesh = new Mesh(edges);
+  for (let tr of allPolygons) {
+    const meshFace = new MeshFace();
+    mergePolygons(tr, meshFace);
+    if (meshFace.polygons.length != 0) {
+      mesh.faces.push(meshFace);
+    }
+  }
+  return mesh;
+};
+