Added ConvexHull, ConvexHull3D, Label and LabeledPolygram

manim/mobject/geometry/polygram.py

@@ -13,6 +13,7 @@
     "Square",
     "RoundedRectangle",
     "Cutout",
+    "ConvexHull",
 ]
 
 
@@ -27,6 +28,7 @@
 from manim.mobject.types.vectorized_mobject import VGroup, VMobject
 from manim.utils.color import BLUE, WHITE, ParsableManimColor
 from manim.utils.iterables import adjacent_n_tuples, adjacent_pairs
+from manim.utils.qhull import QuickHull
 from manim.utils.space_ops import angle_between_vectors, normalize, regular_vertices
 
 if TYPE_CHECKING:
@@ -39,6 +41,7 @@
         InternalPoint3D,
         InternalPoint3D_Array,
         Point3D,
+        Point3D_Array,
     )
     from manim.utils.color import ParsableManimColor
 
@@ -80,7 +83,7 @@ def construct(self):
 
     def __init__(
         self,
-        *vertex_groups: Point3D,
+        *vertex_groups: Point3D_Array,
         color: ParsableManimColor = BLUE,
         **kwargs: Any,
     ):
@@ -780,3 +783,67 @@ def __init__(
         )
         for mobject in mobjects:
             self.append_points(mobject.force_direction(sub_direction).points)
+
+
+class ConvexHull(Polygram):
+    """Constructs a convex hull for a set of points in no particular order.
+
+    Parameters
+    ----------
+    points
+        The points to consider.
+    tolerance
+        The tolerance used by quickhull.
+    kwargs
+        Forwarded to the parent constructor.
+
+    Examples
+    --------
+    .. manim:: ConvexHullExample
+        :save_last_frame:
+        :quality: high
+
+        class ConvexHullExample(Scene):
+            def construct(self):
+                points = [
+                    [-2.35, -2.25, 0],
+                    [1.65, -2.25, 0],
+                    [2.65, -0.25, 0],
+                    [1.65, 1.75, 0],
+                    [-0.35, 2.75, 0],
+                    [-2.35, 0.75, 0],
+                    [-0.35, -1.25, 0],
+                    [0.65, -0.25, 0],
+                    [-1.35, 0.25, 0],
+                    [0.15, 0.75, 0]
+                ]
+                hull = ConvexHull(*points, color=BLUE)
+                dots = VGroup(*[Dot(point) for point in points])
+                self.add(hull)
+                self.add(dots)
+    """
+
+    def __init__(
+        self, *points: Point3D, tolerance: float = 1e-5, **kwargs: Any
+    ) -> None:
+        # Build Convex Hull
+        array = np.array(points)[:, :2]
+        hull = QuickHull(tolerance)
+        hull.build(array)
+
+        # Extract Vertices
+        facets = set(hull.facets) - hull.removed
+        facet = facets.pop()
+        subfacets = list(facet.subfacets)
+        while len(subfacets) <= len(facets):
+            sf = subfacets[-1]
+            (facet,) = hull.neighbors[sf] - {facet}
+            (sf,) = facet.subfacets - {sf}
+            subfacets.append(sf)
+
+        # Setup Vertices as Point3D
+        coordinates = np.vstack([sf.coordinates for sf in subfacets])
+        vertices = np.hstack((coordinates, np.zeros((len(coordinates), 1))))
+
+        # Call Polygram
+        super().__init__(vertices, **kwargs)

manim/mobject/three_d/polyhedra.py

@@ -10,11 +10,20 @@
 from manim.mobject.graph import Graph
 from manim.mobject.three_d.three_dimensions import Dot3D
 from manim.mobject.types.vectorized_mobject import VGroup
+from manim.utils.qhull import QuickHull
 
 if TYPE_CHECKING:
     from manim.mobject.mobject import Mobject
+    from manim.typing import Point3D
 
-__all__ = ["Polyhedron", "Tetrahedron", "Octahedron", "Icosahedron", "Dodecahedron"]
+__all__ = [
+    "Polyhedron",
+    "Tetrahedron",
+    "Octahedron",
+    "Icosahedron",
+    "Dodecahedron",
+    "ConvexHull3D",
+]
 
 
 class Polyhedron(VGroup):
@@ -361,3 +370,91 @@ def __init__(self, edge_length: float = 1, **kwargs):
             ],
             **kwargs,
         )
+
+
+class ConvexHull3D(Polyhedron):
+    """A convex hull for a set of points
+
+    Parameters
+    ----------
+    points
+        The points to consider.
+    tolerance
+        The tolerance used for quickhull.
+    kwargs
+        Forwarded to the parent constructor.
+
+    Examples
+    --------
+    .. manim:: ConvexHull3DExample
+        :save_last_frame:
+        :quality: high
+
+        class ConvexHull3DExample(ThreeDScene):
+            def construct(self):
+                self.set_camera_orientation(phi=75 * DEGREES, theta=30 * DEGREES)
+                points = [
+                    [ 1.93192757,  0.44134585, -1.52407061],
+                    [-0.93302521,  1.23206983,  0.64117067],
+                    [-0.44350918, -0.61043677,  0.21723705],
+                    [-0.42640268, -1.05260843,  1.61266094],
+                    [-1.84449637,  0.91238739, -1.85172623],
+                    [ 1.72068132, -0.11880457,  0.51881751],
+                    [ 0.41904805,  0.44938012, -1.86440686],
+                    [ 0.83864666,  1.66653337,  1.88960123],
+                    [ 0.22240514, -0.80986286,  1.34249326],
+                    [-1.29585759,  1.01516189,  0.46187522],
+                    [ 1.7776499,  -1.59550796, -1.70240747],
+                    [ 0.80065226, -0.12530398,  1.70063977],
+                    [ 1.28960948, -1.44158255,  1.39938582],
+                    [-0.93538943,  1.33617705, -0.24852643],
+                    [-1.54868271,  1.7444399,  -0.46170734]
+                ]
+                hull = ConvexHull3D(
+                    *points,
+                    faces_config = {"stroke_opacity": 0},
+                    graph_config = {
+                        "vertex_type": Dot3D,
+                        "edge_config": {
+                            "stroke_color": BLUE,
+                            "stroke_width": 2,
+                            "stroke_opacity": 0.05,
+                        }
+                    }
+                )
+                dots = VGroup(*[Dot3D(point) for point in points])
+                self.add(hull)
+                self.add(dots)
+    """
+
+    def __init__(self, *points: Point3D, tolerance: float = 1e-5, **kwargs):
+        # Build Convex Hull
+        array = np.array(points)
+        hull = QuickHull(tolerance)
+        hull.build(array)
+
+        # Setup Lists
+        vertices = []
+        faces = []
+
+        # Extract Faces
+        c = 0
+        d = {}
+        facets = set(hull.facets) - hull.removed
+        for facet in facets:
+            tmp = set()
+            for subfacet in facet.subfacets:
+                for point in subfacet.points:
+                    if point not in d:
+                        vertices.append(point.coordinates)
+                        d[point] = c
+                        c += 1
+                    tmp.add(point)
+            faces.append([d[point] for point in tmp])
+
+        # Call Polyhedron
+        super().__init__(
+            vertex_coords=vertices,
+            faces_list=faces,
+            **kwargs,
+        )

manim/utils/polylabel.py

@@ -0,0 +1,156 @@
+#!/usr/bin/env python
+from __future__ import annotations
+
+from queue import PriorityQueue
+from typing import TYPE_CHECKING
+
+import numpy as np
+
+if TYPE_CHECKING:
+    from collections.abc import Sequence
+
+    from manim.typing import Point3D, Point3D_Array
+
+
+class Polygon:
+    """
+    Initializes the Polygon with the given rings.
+
+    Parameters
+    ----------
+    rings
+        A collection of closed polygonal ring.
+    """
+
+    def __init__(self, rings: Sequence[Point3D_Array]) -> None:
+        # Flatten Array
+        csum = np.cumsum([ring.shape[0] for ring in rings])
+        self.array = np.concatenate(rings, axis=0)
+
+        # Compute Boundary
+        self.start = np.delete(self.array, csum - 1, axis=0)
+        self.stop = np.delete(self.array, csum % csum[-1], axis=0)
+        self.diff = np.delete(np.diff(self.array, axis=0), csum[:-1] - 1, axis=0)
+        self.norm = self.diff / np.einsum("ij,ij->i", self.diff, self.diff).reshape(
+            -1, 1
+        )
+
+        # Compute Centroid
+        x, y = self.start[:, 0], self.start[:, 1]
+        xr, yr = self.stop[:, 0], self.stop[:, 1]
+        self.area = 0.5 * (np.dot(x, yr) - np.dot(xr, y))
+        if self.area:
+            factor = x * yr - xr * y
+            cx = np.sum((x + xr) * factor) / (6.0 * self.area)
+            cy = np.sum((y + yr) * factor) / (6.0 * self.area)
+            self.centroid = np.array([cx, cy])
+
+    def compute_distance(self, point: Point3D) -> float:
+        """Compute the minimum distance from a point to the polygon."""
+        scalars = np.einsum("ij,ij->i", self.norm, point - self.start)
+        clips = np.clip(scalars, 0, 1).reshape(-1, 1)
+        d = np.min(np.linalg.norm(self.start + self.diff * clips - point, axis=1))
+        return d if self.inside(point) else -d
+
+    def inside(self, point: Point3D) -> bool:
+        """Check if a point is inside the polygon."""
+        # Views
+        px, py = point
+        x, y = self.start[:, 0], self.start[:, 1]
+        xr, yr = self.stop[:, 0], self.stop[:, 1]
+
+        # Count Crossings (enforce short-circuit)
+        c = (y > py) != (yr > py)
+        c = px < x[c] + (py - y[c]) * (xr[c] - x[c]) / (yr[c] - y[c])
+        return np.sum(c) % 2 == 1
+
+
+class Cell:
+    """
+    A square in a mesh covering the :class:`~.Polygon` passed as an argument.
+
+    Parameters
+    ----------
+    c
+        Center coordinates of the Cell.
+    h
+        Half-Size of the Cell.
+    polygon
+        :class:`~.Polygon` object for which the distance is computed.
+    """
+
+    def __init__(self, c: Point3D, h: float, polygon: Polygon) -> None:
+        self.c = c
+        self.h = h
+        self.d = polygon.compute_distance(self.c)
+        self.p = self.d + self.h * np.sqrt(2)
+
+    def __lt__(self, other: Cell) -> bool:
+        return self.d < other.d
+
+    def __gt__(self, other: Cell) -> bool:
+        return self.d > other.d
+
+    def __le__(self, other: Cell) -> bool:
+        return self.d <= other.d
+
+    def __ge__(self, other: Cell) -> bool:
+        return self.d >= other.d
+
+
+def polylabel(rings: Sequence[Point3D_Array], precision: float = 0.01) -> Cell:
+    """
+    Finds the pole of inaccessibility (the point that is farthest from the edges of the polygon)
+    using an iterative grid-based approach.
+
+    Parameters
+    ----------
+    rings
+        A list of lists, where each list is a sequence of points representing the rings of the polygon.
+        Typically, multiple rings indicate holes in the polygon.
+    precision
+        The precision of the result (default is 0.01).
+
+    Returns
+    -------
+    Cell
+        A Cell containing the pole of inaccessibility to a given precision.
+    """
+    # Precompute Polygon Data
+    array = [np.array(ring)[:, :2] for ring in rings]
+    polygon = Polygon(array)
+
+    # Bounding Box
+    mins = np.min(polygon.array, axis=0)
+    maxs = np.max(polygon.array, axis=0)
+    dims = maxs - mins
+    s = np.min(dims)
+    h = s / 2.0
+
+    # Initial Grid
+    queue = PriorityQueue()
+    xv, yv = np.meshgrid(np.arange(mins[0], maxs[0], s), np.arange(mins[1], maxs[1], s))
+    for corner in np.vstack([xv.ravel(), yv.ravel()]).T:
+        queue.put(Cell(corner + h, h, polygon))
+
+    # Initial Guess
+    best = Cell(polygon.centroid, 0, polygon)
+    bbox = Cell(mins + (dims / 2), 0, polygon)
+    if bbox.d > best.d:
+        best = bbox
+
+    # While there are cells to consider...
+    directions = np.array([[-1, -1], [1, -1], [-1, 1], [1, 1]])
+    while not queue.empty():
+        cell = queue.get()
+        if cell > best:
+            best = cell
+        # If a cell is promising, subdivide!
+        if cell.p - best.d > precision:
+            h = cell.h / 2.0
+            offsets = cell.c + directions * h
+            queue.put(Cell(offsets[0], h, polygon))
+            queue.put(Cell(offsets[1], h, polygon))
+            queue.put(Cell(offsets[2], h, polygon))
+            queue.put(Cell(offsets[3], h, polygon))
+    return best