render per-triangle info in menpo3d.ipynb

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   "cell_type": "code",
   "execution_count": 72,
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   "source": [
    "import numpy as np\n",
    "from menpo.shape import TriMesh\n",
    "\n",
    "def duplicate_vertices(mesh):\n",
    "    # generate a new mesh with unique vertices per triangle\n",
    "    # (i.e. duplicate verts so that each triangle is unique)    old_to_new = mesh.trilist.ravel()\n",
    "    old_to_new = mesh.trilist.ravel()\n",
    "    new_trilist = np.arange(old_to_new.shape[0]).reshape([-1, 3])\n",
    "    new_points = mesh.points[old_to_new]\n",
    "    return TriMesh(new_points, trilist=new_trilist), old_to_new"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 73,
   "metadata": {
    "collapsed": false
   },
   "outputs": [],
   "source": [
    "import menpo3d.io as m3io\n",
    "\n",
    "mesh = m3io.import_builtin_asset.james_obj()"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 74,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "[  0.   1.   2.   3.   4.   5.   6.   7.   8.   9.  10.  11.  12.  13.  14.]\n"
     ]
    }
   ],
   "source": [
    "# switch this out for your unwrapped one!\n",
    "mesh_unwrapped = mesh\n",
    "\n",
    "# and do your logic here...\n",
    "id_per_vertex = np.floor(mesh_unwrapped.points[:, 0] / 25)\n",
    "id_per_vertex = id_per_vertex - min(id_per_vertex)\n",
    "print(np.unique(id_per_vertex))"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 75,
   "metadata": {
    "collapsed": false
   },
   "outputs": [],
   "source": [
    "# bin the meshes based on the first vertex of each triangle\n",
    "v1 = mesh.trilist[:, 0]\n",
    "id_per_tri = id_per_vertex[v1]"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 76,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "TriMesh: n_points: 205458, n_dims: 3, n_tris: 68486\n"
     ]
    }
   ],
   "source": [
    "mesh_uniq_verts, vertex_map = duplicate_vertices(mesh)\n",
    "print(mesh_uniq_verts)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 77,
   "metadata": {
    "collapsed": false
   },
   "outputs": [],
   "source": [
    "# we know trilist is of form\n",
    "# 0, 1, 2\n",
    "# 3, 4, 5...\n",
    "# -> first 3 vertices are first tri\n",
    "# etc etc\n",
    "id_per_v_per_t = np.repeat(id_per_tri, 3)\n",
    "\n",
    "# use this guy in the rasterizer!\n",
    "f3v = np.tile(id_per_v_per_t, (3, 1)).T"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 78,
   "metadata": {
    "collapsed": false
   },
   "outputs": [],
   "source": [
    "from menpo3d.rasterize import GLRasterizer\n",
    "\n",
    "# your rasterizer here sir...\n",
    "rasterizer = GLRasterizer()\n",
    "rgb_image, id_image = rasterizer.rasterize_mesh_with_f3v_interpolant(mesh_uniq_verts, per_vertex_f3v=f3v)"
   ]
  }
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