{
 "cells": [
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# Polygons"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "`scikit-geometry` can handle polygons, as well as polygons with holes. Polygons can be created from lists of points."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "import skgeom as sg\n",
    "from skgeom.draw import draw"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "poly = sg.Polygon([sg.Point2(0, 0), sg.Point2(0, 3), sg.Point2(3, 3)])"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "draw(poly)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "You may also use lists of coordinates or numpy arrays to construct polygons:"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "sg.Polygon([[0, 0], [0, 3], [3, 3]])"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Likewise, you can access a Polygon's vertices as either a list of `Point2`s or as a numpy array:"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "list(poly.vertices)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "poly.coords"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "We can check wether a given point is _inside_ the polygon (a negative sign means outside, positive means inside):"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "poly.oriented_side(sg.Point2(1, 2))"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "poly.oriented_side(sg.Point2(2, 1))"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Calculate the bounding box"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "poly.bbox()"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Compute the area of the polygon. Note: the sign depends on the order of the polygon (clockwise → negative, counter-clockwise → positive)."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "poly.area()"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "poly.orientation() == sg.Sign.CLOCKWISE"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "poly.is_convex()"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "poly.is_simple()"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Polygon with Holes"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "We can cut out an area of a Polygon by adding one or multiple holes."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "hole = sg.Polygon([\n",
    "    sg.Point2(1.0, 2.0),\n",
    "    sg.Point2(1.0, 2.5),\n",
    "    sg.Point2(0.5, 2.5),\n",
    "    sg.Point2(0.5, 2.0)]\n",
    ")\n",
    "poly_with_hole = sg.PolygonWithHoles(poly, [hole])"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "draw(poly_with_hole)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Boolean operations on Polygons\n",
    "\n",
    "*scikit-geometry* supports boolean operations on polygons, such as computing the union, difference and intersection between two polygons (or polygons with holes)."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "poly1 = sg.Polygon([sg.Point2(3, 0), sg.Point2(3, 3), sg.Point2(0, 3), sg.Point2(0, 0)])\n",
    "poly2 = sg.Polygon([sg.Point2(5, 2), sg.Point2(5, 5), sg.Point2(2, 5), sg.Point2(2, 2)])"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "draw(poly1, facecolor='red')\n",
    "draw(poly2, facecolor='blue')"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "from skgeom import boolean_set"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "draw(boolean_set.join(poly1, poly2))"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "draw(boolean_set.difference(poly1, poly2))"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "draw(boolean_set.symmetric_difference(poly1, poly2))"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "draw(boolean_set.intersect(poly1, poly2))"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Minkowski Sum of 2 Polygons\n",
    "\n",
    "We can compute the minkowski sum of two polygons easily (i.e. offsetting a polygon with another polygon)."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "from skgeom import minkowski"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "p1 = sg.Polygon([sg.Point2(-1, -1), sg.Point2(1, -1), sg.Point2(0, 1)])\n",
    "p2 = sg.Polygon([sg.Point2(3, -1), sg.Point2(5, -1), sg.Point2(5, 1), sg.Point2(3, 1)])"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "draw(p1, facecolor='red')\n",
    "draw(p2, facecolor='blue')"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "result = minkowski.minkowski_sum(p1, p2)\n",
    "draw(result)"
   ]
  }
 ],
 "metadata": {
  "kernelspec": {
   "display_name": "Python 3",
   "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": "3.7.3"
  }
 },
 "nbformat": 4,
 "nbformat_minor": 2
}