{
 "cells": [
  {
   "cell_type": "markdown",
   "id": "a1",
   "metadata": {},
   "source": [
    "# Isosurfaces\n",
    "\n",
    "Isosurface rendering extracts and displays the zero level-set of a scalar function inside a 3D mesh. A second function can be colored on the isosurface."
   ]
  },
  {
   "cell_type": "markdown",
   "id": "a2",
   "metadata": {},
   "source": [
    "## Basic Isosurface\n",
    "\n",
    "Render the zero level-set of a function, colored by another function:"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "id": "a3",
   "metadata": {},
   "outputs": [],
   "source": [
    "from netgen.occ import *\n",
    "from ngsolve import *\n",
    "from ngsolve_webgpu.mesh import MeshData\n",
    "from ngsolve_webgpu.cf import FunctionData\n",
    "from ngsolve_webgpu.isosurface import IsoSurfaceRenderer, NegativeSurfaceRenderer, NegativeClippingRenderer\n",
    "from webgpu.clipping import Clipping\n",
    "from webgpu.colormap import Colorbar, Colormap\n",
    "from webgpu.jupyter import Draw\n",
    "\n",
    "box = Box((-1, -1, -1), (1, 1, 1))\n",
    "mesh = Mesh(OCCGeometry(box).GenerateMesh(maxh=0.2))\n",
    "\n",
    "gf = GridFunction(H1(mesh, order=2))\n",
    "levelset = 0.8**2 - (x**2 + y**2 + z**2)\n",
    "gf.Set(levelset)\n",
    "\n",
    "mesh_data = MeshData(mesh)\n",
    "colormap = Colormap()\n",
    "clipping = Clipping()\n",
    "\n",
    "func_data = FunctionData(mesh_data, x, order=2)\n",
    "levelset_data = FunctionData(mesh_data, -gf, order=2)\n",
    "\n",
    "iso = IsoSurfaceRenderer(func_data, levelset_data, clipping, colormap)\n",
    "neg_surface = NegativeSurfaceRenderer(func_data, levelset_data, clipping=clipping, colormap=colormap)\n",
    "neg_clip = NegativeClippingRenderer(func_data, levelset_data, clipping, colormap)\n",
    "\n",
    "clipping.mode = clipping.Mode.PLANE\n",
    "scene = Draw([iso, neg_clip, neg_surface, Colorbar(colormap)])"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "a4",
   "metadata": {},
   "source": [
    "Three renderers work together:\n",
    "\n",
    "- **`IsoSurfaceRenderer`** — extracts and renders the zero level-set surface via a compute shader. The level-set data is negated by convention (negative = inside).\n",
    "- **`NegativeSurfaceRenderer`** — renders the outer mesh surface only where the level-set is negative (inside the domain).\n",
    "- **`NegativeClippingRenderer`** — renders the clipping cross-section only inside the level-set domain."
   ]
  },
  {
   "cell_type": "markdown",
   "id": "a5",
   "metadata": {},
   "source": [
    "## Updating the Level Set\n",
    "\n",
    "The isosurface updates when the underlying `GridFunction` changes and `scene.redraw()` is called."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "id": "a6",
   "metadata": {},
   "outputs": [],
   "source": [
    "gf.Set(0.5**2 - (x**2 + y**2 + z**2))\n",
    "scene.redraw()"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "id": "deb6e1a2-afd5-4b68-b9ce-20dc7b2ba4a8",
   "metadata": {},
   "outputs": [],
   "source": []
  }
 ],
 "metadata": {
  "kernelspec": {
   "display_name": "Python 3 (ipykernel)",
   "language": "python",
   "name": "python3"
  },
  "language_info": {
   "codemirror_mode": {
    "name": "ipython",
    "version": 3
   },
   "file_extension": ".py",
   "mimetype": "text/x-python",
   "name": "python",
   "nbconvert_exporter": "python",
   "pygments_lexer": "ipython3",
   "version": "3.14.5"
  }
 },
 "nbformat": 4,
 "nbformat_minor": 5
}