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    "# Animation & Live Updates\n",
    "\n",
    "Solutions can be updated interactively using `scene.redraw()` or animated over stored timesteps using the `Animation` wrapper. When the documentation is exported to HTML, the `Animation` wrapper additionally serializes every recorded frame into the page so the slider keeps working in the static export — no Python kernel required."
   ]
  },
  {
   "cell_type": "markdown",
   "id": "a2",
   "metadata": {},
   "source": [
    "## Live redrawing with parameters\n",
    "\n",
    "Update a scene when an NGSolve `Parameter` changes — useful in a live notebook session:"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "id": "a3",
   "metadata": {},
   "outputs": [],
   "source": [
    "from ngsolve import *\n",
    "from ngsolve_webgpu.jupyter import Draw\n",
    "\n",
    "mesh = Mesh(unit_square.GenerateMesh(maxh=0.1))\n",
    "p = Parameter(10)\n",
    "scene = Draw(sin(p * x) * sin(10 * y), mesh, order=3)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "id": "a4",
   "metadata": {},
   "outputs": [],
   "source": [
    "# Change parameter and redraw (only effective in a live kernel)\n",
    "p.Set(20)\n",
    "scene.redraw()"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "a8",
   "metadata": {},
   "source": [
    "## Timestep animation with `Animation`\n",
    "\n",
    "`Animation` wraps a renderer, walks its CoefficientFunction tree for `GridFunction` and `Parameter` objects, and records snapshots when you call `add_time()`. A slider in the GUI scrubs through the recorded frames.\n",
    "\n",
    "**Important for HTML export:** record all frames *before* calling `Draw()`. The export hook runs at `Draw()` time, snapshots the per-frame GPU buffers, and embeds them in the page. Frames added after `Draw()` won't appear in the static export."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "id": "a9",
   "metadata": {},
   "outputs": [],
   "source": [
    "from ngsolve import *\n",
    "from ngsolve_webgpu.mesh import MeshData\n",
    "from ngsolve_webgpu.cf import FunctionData, CFRenderer\n",
    "from ngsolve_webgpu.animate import Animation\n",
    "from webgpu.colormap import Colorbar\n",
    "from webgpu.jupyter import Draw\n",
    "\n",
    "mesh = Mesh(unit_square.GenerateMesh(maxh=0.1))\n",
    "gf = GridFunction(H1(mesh, order=3))\n",
    "t = Parameter(0)\n",
    "f = sin(10 * (x - 0.1 * t))\n",
    "\n",
    "gf.Interpolate(f)\n",
    "\n",
    "md = MeshData(mesh)\n",
    "fd = FunctionData(md, gf, order=3)\n",
    "cfr = CFRenderer(fd)\n",
    "cfr.colormap.set_min_max(-1, 1)\n",
    "\n",
    "ani = Animation(cfr)\n",
    "ani.add_time()  # frame 0 (current state)\n",
    "\n",
    "# Record 20 frames before drawing — they will all be embedded in the HTML\n",
    "for tval in range(1, 21):\n",
    "    t.Set(tval * 5)\n",
    "    gf.Interpolate(f)\n",
    "    ani.add_time()\n",
    "\n",
    "Draw([ani, Colorbar(cfr.colormap)])"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "a11",
   "metadata": {},
   "source": [
    "Drag the **Frame** slider in the GUI panel to scrub through the recorded timesteps. In the live notebook the same scene also reacts to `add_time()` calls made *after* `Draw` — for example inside a time-stepping loop — and `scene.redraw()` will update the canvas.\n",
    "\n",
    "### What gets exported\n",
    "\n",
    "For each recorded frame, `Animation.get_export_interactions()` re-evaluates the underlying CF, reads back the relevant GPU buffers (`data_2d`, `data_3d`), and stores them as raw frame snapshots. The JS engine's `time_animation` handler uploads the matching snapshot to the live buffer when the slider moves and triggers a re-render — purely client-side."
   ]
  }
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