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    "\n",
    "!pip install ogre-python\n",
    "\n",
    "import matplotlib.pyplot as plt\n",
    "import numpy as np\n",
    "\n",
    "import Ogre\n",
    "import Ogre.Bites\n",
    "import Ogre.RTShader\n",
    "\n",
    "class Application(Ogre.Bites.ApplicationContextBase):\n",
    "    def __init__(self):\n",
    "        Ogre.Bites.ApplicationContextBase.__init__(self, \"OgreColab\")\n",
    "\n",
    "    def oneTimeConfig(self):\n",
    "        rs = self.getRoot().getRenderSystemByName(\"OpenGL 3+ Rendering Subsystem\")\n",
    "        self.getRoot().setRenderSystem(rs)\n",
    "        return True\n",
    "\n",
    "    def pollEvents(self):\n",
    "        pass\n",
    "\n",
    "\n",
    "ctx = Application()\n",
    "ctx.initApp()\n",
    "root = ctx.getRoot()\n",
    "\n",
    "scn_mgr = root.createSceneManager()\n",
    "\n",
    "shadergen = Ogre.RTShader.ShaderGenerator.getSingleton()\n",
    "shadergen.addSceneManager(scn_mgr)\n",
    "\n",
    "# no RenderWindows are available here, so create an offscreen rendertarget and use that\n",
    "w, h = 640, 480\n",
    "tex = Ogre.TextureManager.getSingleton().createManual(\n",
    "    \"target\", Ogre.RGN_DEFAULT, Ogre.TEX_TYPE_2D, w, h, 0, Ogre.PF_BYTE_RGB,\n",
    "    Ogre.TU_RENDERTARGET, None)\n",
    "win = tex.getBuffer().getRenderTarget()\n"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "# this is the same code as in the numpy_sample.py example\n",
    "cam = scn_mgr.createCamera(\"myCam\")\n",
    "vp = win.addViewport(cam)\n",
    "\n",
    "# create a numpy image\n",
    "arr = np.zeros((256, 256, 3), dtype=np.uint8)\n",
    "arr[:, :, 1] = np.mgrid[0:256, 0:256][1]\n",
    "\n",
    "# convert to an Ogre image and create a texture out of it\n",
    "ogre_img = Ogre.Image()\n",
    "ogre_img.loadDynamicImage(arr, 256, 256, Ogre.PF_BYTE_RGB)\n",
    "\n",
    "Ogre.TextureManager.getSingleton().loadImage(\"gradient\", \"General\", ogre_img)\n",
    "\n",
    "## apply texture to a rectangle\n",
    "mat = Ogre.MaterialManager.getSingleton().create(\"gradient_mat\", \"General\")\n",
    "rpass = mat.getTechniques()[0].getPasses()[0]\n",
    "rpass.setLightingEnabled(False)\n",
    "rpass.createTextureUnitState(\"gradient\")\n",
    "\n",
    "rect = scn_mgr.createScreenSpaceRect(True)\n",
    "rect.setCorners(-0.5, 0.5, 0.5, -0.5)  # in normalized screen space\n",
    "rect.setMaterial(mat)\n",
    "\n",
    "scn_mgr.getRootSceneNode().createChildSceneNode().attachObject(rect)\n",
    "\n",
    "vp.setBackgroundColour((0.3, 0.3, 0.3))\n",
    "\n",
    "win.update()\n",
    "\n",
    "## read back the pixels to a numpy array\n",
    "mem = np.empty((win.getHeight(), win.getWidth(), 3), dtype=np.uint8)\n",
    "pb = Ogre.PixelBox(win.getWidth(), win.getHeight(), 1, Ogre.PF_BYTE_RGB, mem)\n",
    "win.copyContentsToMemory(pb, pb)\n",
    "\n",
    "plt.imshow(mem)\n"
   ]
  }
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