Restore Colab support for example notebooks

examples/PD_controller.ipynb

@@ -6,7 +6,11 @@
    "source": [
     "# `JAXsim` Showcase: PD Controller\n",
     "\n",
-    "First, we install the necessary packages and import them."
+    "First, we install the necessary packages and import them.\n",
+    "\n",
+    "<a target=\"_blank\" href=\"https://colab.research.google.com/github/ami-iit/jaxsim/blob/main/examples/PD_controller.ipynb\">\n",
+    "  <img src=\"https://colab.research.google.com/assets/colab-badge.svg\" alt=\"Open In Colab\"/>\n",
+    "</a>"
    ]
   },
   {
@@ -19,6 +23,28 @@
     "from IPython.display import clear_output, HTML, display\n",
     "import sys\n",
     "\n",
+    "IS_COLAB = \"google.colab\" in sys.modules\n",
+    "\n",
+    "# Install JAX and Gazebo SDF\n",
+    "if IS_COLAB:\n",
+    "    !{sys.executable} -m pip install -qU jaxsim[viz]\n",
+    "    !apt install -qq lsb-release wget gnupg\n",
+    "    !wget https://packages.osrfoundation.org/gazebo.gpg -O /usr/share/keyrings/pkgs-osrf-archive-keyring.gpg\n",
+    "    !echo \"deb [arch=$(dpkg --print-architecture) signed-by=/usr/share/keyrings/pkgs-osrf-archive-keyring.gpg] http://packages.osrfoundation.org/gazebo/ubuntu-stable $(lsb_release -cs) main\" | sudo tee /etc/apt/sources.list.d/gazebo-stable.list > /dev/null\n",
+    "    !apt -qq update\n",
+    "    !apt install -qq --no-install-recommends libsdformat13 gz-tools2\n",
+    "\n",
+    "    # Optional dependency for visualization\n",
+    "    !{sys.executable} -m pip install pyvirtualdisplay\n",
+    "    !apt install xvfb\n",
+    "\n",
+    "    # Start Xvfb and set \"DISPLAY\" environment variable\n",
+    "    import pyvirtualdisplay\n",
+    "    d = pyvirtualdisplay.Display()\n",
+    "    d.start()\n",
+    "\n",
+    "    clear_output()\n",
+    "\n",
     "import jax\n",
     "import jax.numpy as jnp\n",
     "from jaxsim import logging\n",
@@ -124,29 +150,50 @@
    "source": [
     "# @title Set up MuJoCo renderer\n",
     "\n",
-    "from jaxsim.mujoco.visualizer import MujocoVisualizer\n",
     "from jaxsim.mujoco import RodModelToMjcf, MujocoModelHelper, MujocoVideoRecorder\n",
     "from jaxsim.mujoco.loaders import UrdfToMjcf\n",
     "\n",
+    "import os\n",
+    "import subprocess\n",
+    "\n",
+    "\n",
+    "if IS_COLAB:\n",
+    "    if subprocess.run(\"ffmpeg -version\", shell=True).returncode:\n",
+    "        !command -v ffmpeg >/dev/null || (apt update && apt install -y ffmpeg)\n",
+    "        clear_output()\n",
+    "\n",
+    "    if subprocess.run(\"nvidia-smi\").returncode:\n",
+    "        raise RuntimeError(\n",
+    "            \"Cannot communicate with GPU. \"\n",
+    "            \"Make sure you are using a GPU Colab runtime. \"\n",
+    "            \"Go to the Runtime menu and select Choose runtime type.\"\n",
+    "        )\n",
+    "\n",
+    "    # Add an ICD config so that glvnd can pick up the Nvidia EGL driver.\n",
+    "    # This is usually installed as part of an Nvidia driver package, but the Colab\n",
+    "    # kernel doesn't install its driver via APT, and as a result the ICD is missing.\n",
+    "    # (https://github.com/NVIDIA/libglvnd/blob/master/src/EGL/icd_enumeration.md)\n",
+    "    NVIDIA_ICD_CONFIG_PATH = \"/usr/share/glvnd/egl_vendor.d/10_nvidia.json\"\n",
+    "    if not os.path.exists(NVIDIA_ICD_CONFIG_PATH):\n",
+    "        with open(NVIDIA_ICD_CONFIG_PATH, \"w\") as f:\n",
+    "            f.write(\n",
+    "                \"\"\"{\n",
+    "      \"file_format_version\" : \"1.0.0\",\n",
+    "      \"ICD\" : {\n",
+    "         \"library_path\" : \"libEGL_nvidia.so.0\"\n",
+    "     }\n",
+    "  }\n",
+    "  \"\"\"\n",
+    "            )\n",
     "\n",
     "%env MUJOCO_GL=egl\n",
     "\n",
-    "try:\n",
-    "    import mujoco\n",
-    "except Exception as e:\n",
-    "    raise e from RuntimeError(\n",
-    "        \"Something went wrong during installation. Check the shell output above \"\n",
-    "        \"for more information.\\n\"\n",
-    "        \"If using a hosted Colab runtime, make sure you enable GPU acceleration \"\n",
-    "        'by going to the Runtime menu and selecting \"Choose runtime type\".'\n",
-    "    )\n",
-    "\n",
     "camera = {\n",
-    "    \"name\":\"cartpole_camera\",\n",
-    "    \"mode\":\"fixed\",\n",
-    "    \"pos\":\"3.954 3.533 2.343\",\n",
-    "    \"xyaxes\":\"-0.594 0.804 -0.000 -0.163 -0.120 0.979\",\n",
-    "    \"fovy\":\"60\",\n",
+    "    \"name\": \"cartpole_camera\",\n",
+    "    \"mode\": \"fixed\",\n",
+    "    \"pos\": \"3.954 3.533 2.343\",\n",
+    "    \"xyaxes\": \"-0.594 0.804 -0.000 -0.163 -0.120 0.979\",\n",
+    "    \"fovy\": \"60\",\n",
     "}\n",
     "\n",
     "mjcf_string, assets = UrdfToMjcf.convert(urdf=model.built_from, cameras=camera)\n",

examples/Parallel_computing.ipynb

@@ -25,7 +25,16 @@
     "\n",
     "from IPython.display import HTML, clear_output, display\n",
     "\n",
+    "IS_COLAB = \"google.colab\" in sys.modules\n",
+    "\n",
     "# Install JAX and Gazebo\n",
+    "if IS_COLAB:\n",
+    "    !{sys.executable} -m pip install -qU jaxsim\n",
+    "    !apt install -qq lsb-release wget gnupg\n",
+    "    !wget https://packages.osrfoundation.org/gazebo.gpg -O /usr/share/keyrings/pkgs-osrf-archive-keyring.gpg\n",
+    "    !echo \"deb [arch=$(dpkg --print-architecture) signed-by=/usr/share/keyrings/pkgs-osrf-archive-keyring.gpg] http://packages.osrfoundation.org/gazebo/ubuntu-stable $(lsb_release -cs) main\" | sudo tee /etc/apt/sources.list.d/gazebo-stable.list > /dev/null\n",
+    "    !apt -qq update\n",
+    "    !apt install -qq --no-install-recommends libsdformat13 gz-tools2\n",
     "\n",
     "# Set environment variable to avoid GPU out of memory errors\n",
     "%env XLA_PYTHON_CLIENT_MEM_PREALLOCATE=false\n",

examples/README.md

@@ -4,15 +4,27 @@ This folder includes a Jupyter Notebook demonstrating the practical usage of JAX
 
 ### Examples
 
-- [PD_controller](./PD_controller.ipynb) - A simple example demonstrating the use of JAXsim to simulate a PD controller with gravity compensation for a 2-DOF cartpole.
-- [Parallel_computing](./Parallel_computing.ipynb) - An example demonstrating how to simulate vectorized models in parallel using JAXsim.
+- [PD_controller](./PD_controller.ipynb) <a target="_blank" href="https://colab.research.google.com/github/ami-iit/jaxsim/blob/main/examples/PD_controller.ipynb">
+  <img src="https://colab.research.google.com/assets/colab-badge.svg" alt="Open In Colab"/>
+</a> - A simple example demonstrating the use of JAXsim to simulate a PD controller with gravity compensation for a 2-DOF cartpole.
+- [Parallel_computing](./Parallel_computing.ipynb) <a target="_blank" href="https://colab.research.google.com/github/ami-iit/jaxsim/blob/main/examples/Parallel_computing.ipynb">
+  <img src="https://colab.research.google.com/assets/colab-badge.svg" alt="Open In Colab"/>
+</a> - An example demonstrating how to simulate vectorized models in parallel using JAXsim.
 
 > [!TIP]
 > Stay tuned for more examples!
 
 ## Running the Examples
 
-To execute these examples utilizing JAXsim with hardware acceleration, you can use [pixi](https://pixi.sh) to run the examples in a local environment:
+To execute these examples utilizing JAXsim with hardware acceleration, there are a couple of options available:
+
+### Option 1: Google Colab (Recommended)
+
+The simplest way to run the examples is by accessing the provided Google Colab notebook link mentioned above. This will enable you to execute the examples in a hosted environment.
+
+### Option 2: Local Execution with `pixi`
+
+For local execution, follow these steps:
 
 1. **Install `pixi`:**