{
 "cells": [
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "\"\"\"\n",
    "Given a mesh and two vertex indices find the shortest path\n",
    "between the two vertices while only traveling along edges\n",
    "of the mesh using a distance-weighted graph search.\n",
    "\"\"\""
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "import networkx as nx\n",
    "\n",
    "import trimesh"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "# test on a sphere mesh\n",
    "mesh = trimesh.primitives.Sphere()"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "# edges without duplication\n",
    "edges = mesh.edges_unique"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "# the actual length of each unique edge\n",
    "length = mesh.edges_unique_length"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "# create the graph with edge attributes for length\n",
    "g = nx.Graph()\n",
    "for edge, L in zip(edges, length):\n",
    "    g.add_edge(*edge, length=L)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "# arbitrary indices of mesh.vertices to test with\n",
    "start = 0\n",
    "end = int(len(mesh.vertices) / 2.0)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "# run the shortest path query using length for edge weight\n",
    "path = nx.shortest_path(g, source=start, target=end, weight=\"length\")"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "# VISUALIZE RESULT\n",
    "# make the sphere white\n",
    "mesh.visual.face_colors = [255, 255, 255, 255]\n",
    "# Path3D with the path between the points\n",
    "path_visual = trimesh.load_path(mesh.vertices[path])"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "# create a scene with the mesh, path, and points\n",
    "scene = trimesh.Scene([path_visual, mesh])"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "scene.show()"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": []
  }
 ],
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