spatialmath-python/spatialmath/geom2d.py at master · lippyRobotics/spatialmath-python

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#!/usr/bin/env python3
# -*- coding: utf-8 -*-
Created on Sun Jul  5 09:42:30 2020
@author: corkep
from functools import reduce
from spatialmath.base.graphics import axes_logic
from spatialmath import base, SE2
import matplotlib.pyplot as plt
from matplotlib.path import Path
from matplotlib.patches import PathPatch
from matplotlib.transforms import Affine2D
from matplotlib.collections import PatchCollection
import numpy as np
class Polygon2:
    Class to represent 2D (planar) polygons
    .. note:: Uses Matplotlib primitives to perform transformations and 
        intersections.
    def __init__(self, vertices=None):
        """
        Create planar polygon from vertices
        :param vertices: vertices of polygon, defaults to None
        :type vertices: ndarray(2, N), optional
        Create a polygon from a set of points provided as columns of the 2D
        array ``vertices``.
        A closed polygon is created so the last vertex should not equal the
        first.
        Example:
        .. runblock:: pycon
            >>> from spatialmath import Polygon2
            >>> p = Polygon2([[1, 3, 2], [2, 2, 4]])
        .. warning:: The points must be sequential around the perimeter and
            counter clockwise.
        .. note:: The polygon is represented by a Matplotlib ``Path``
        """
        if isinstance(vertices, (list, tuple)):
            vertices = np.array(vertices).T
        elif isinstance(vertices, np.ndarray):
            if vertices.shape[0] != 2:
                raise ValueError('ndarray must be 2xN')
        elif vertices is None:
            return
        else:
            raise TypeError('expecting list of 2-tuples or ndarray(2,N)')
        # replicate the first vertex to make it closed.
        # setting closed=False and codes=None leads to a different
        # path which gives incorrect intersection results
        vertices = np.hstack((vertices, vertices[:, 0:1]))
        self.path = Path(vertices.T, closed=True)
        self.path0 = self.path
    def __str__(self):
        """
        Polygon to string
        :return: brief summary of polygon
        :rtype: str
        Example:
        .. runblock:: pycon
            >>> from spatialmath import Polygon2
            >>> p = Polygon2([[1, 3, 2], [2, 2, 4]])
            >>> print(p)
        """
        return f"Polygon2 with {len(self.path)} vertices"
    def __len__(self):
        """
        Number of vertices in polygon
        :return: number of vertices
        :rtype: int
        Example:
        .. runblock:: pycon
            >>> from spatialmath import Polygon2
            >>> p = Polygon2([[1, 3, 2], [2, 2, 4]])
            >>> len(p)
        """
        return len(self.path)
    def plot(self, ax=None, **kwargs):
        """
        Plot polygon
        :param ax: axes in which to draw the polygon, defaults to None
        :type ax: Axes, optional
        :param kwargs: options passed to Matplotlib ``Patch``
        A Matplotlib Patch is created with the passed options ``**kwargs`` and
        added to the axes.
        :seealso: :meth:`animate` :func:`matplotlib.PathPatch`
        """
        self.patch = PathPatch(self.path, **kwargs)
        ax = base.axes_logic(ax, 2)
        ax.add_patch(self.patch)
        plt.draw()
        self.kwargs = kwargs
        self.ax = ax
    def animate(self, T, **kwargs):
        """
        Animate a polygon
        :param T: new pose of Polygon
        :type T: SE2
        :param kwargs: options passed to Matplotlib ``Patch``
        The plotted polygon is moved to the pose given by ``T``. The pose is
        always with respect to the initial vertices when the polygon was
        constructed.  The vertices of the polygon will be updated to reflect
        what is plotted.
        If the polygon has already plotted, it will keep the same graphical
        attributes.  If new attributes are given they will replace those
        given at construction time.
        :seealso: :meth:`plot`
        """
        # get the path
        if self.patch is not None:
            self.patch.remove()
        self.path = self.path0.transformed(Affine2D(T.A))
        if len(kwargs) > 0:
            self.args = kwargs
        self.patch = PathPatch(self.path, **self.kwargs)
        self.ax.add_patch(self.patch)
    def contains(self, p, radius=0.0):
        """
        Test if point is inside polygon
        :param p: point
        :type p: array_like(2)
        :param radius: Add an additional margin to the polygon boundary, defaults to 0.0
        :type radius: float, optional
        :return: True if point is contained by polygon
        :rtype: bool
        ``radius`` can be used to inflate the polygon, or if negative, to 
        deflated it.
        Example:
        .. runblock:: pycon
            >>> from spatialmath import Polygon2
            >>> p = Polygon2([[1, 3, 2], [2, 2, 4]])
            >>> p.contains([0, 0])
            >>> p.contains([2, 3])
        .. warning:: Returns True if the point is on the edge of the polygon
            but False if the point is one of the vertices.
        .. warning:: For a polygon with clockwise ordering of vertices the 
            sign of ``radius`` is flipped.
        :seealso: :func:`matplotlib.contains_point`
        """
        # note the sign of radius is negated if the polygon is drawn clockwise
        # https://stackoverflow.com/questions/45957229/matplotlib-path-contains-points-radius-parameter-defined-inconsistently
        # edges are included but the corners are not
        if isinstance(p, (list, tuple)) or (isinstance(p, np.ndarray) and p.ndim == 1):
            return self.path.contains_point(tuple(p), radius=radius)
        else:
            return self.path.contains_points(p.T, radius=radius)
    def bbox(self):
        """
        Bounding box of polygon
        :return: bounding box as [xmin, xmax, ymin, ymax]
        :rtype: ndarray(4)
        Example:
        .. runblock:: pycon
            >>> from spatialmath import Polygon2
            >>> p = Polygon2([[1, 3, 2], [2, 2, 4]])
            >>> p.bbox()
        """
        return np.array(self.path.get_extents()).ravel(order='F')
    def radius(self):
        """
        Radius of smallest enclosing circle
        :return: radius
        :rtype: float
        This is the radius of the smalleset circle, centred at the centroid,
        that encloses all vertices.
        Example:
        .. runblock:: pycon
            >>> from spatialmath import Polygon2
            >>> p = Polygon2([[1, 3, 2], [2, 2, 4]])
            >>> p.radius()
        """
        c = self.centroid()
        dmax = -np.inf
        for vertex in self.path.vertices:
            d = np.linalg.norm(vertex - c)
            if d > dmax:
                dmax = d
        return d
    def intersects(self, other):
        """
        Test for intersection
        :param other: object to test for intersection
        :type other: Polygon2 or Line2
        :return: True if the polygon intersects ``other``
        :rtype: bool
        """
        if isinstance(other, Polygon2):
            # polygon-polygon intersection is done by matplotlib
            return self.path.intersects_path(other.path, filled=True)
        elif isinstance(other, Line2):
            # polygon-line intersection
            for p1, p2 in self.segments():
                # test each edge segment against the line
                if other.intersect_segment(p1, p2):
                    return True
            return False
        elif isinstance(other, (list, tuple)):
            for polygon in other:
                if self.path.intersects_path(polygon.path, filled=True):
                    return True
            return False
    def transformed(self, T):
        """
        A transformed copy of polygon
        :param T: planar transformation
        :type T: SE2
        :return: transformed polygon
        :rtype: Polygon2
        Returns a new polgyon whose vertices have been transformed by ``T``.
        Example:
        .. runblock:: pycon
            >>> from spatialmath import Polygon2, SE2
            >>> p = Polygon2([[1, 3, 2], [2, 2, 4]])
            >>> p.vertices()
            >>> p.transformed(SE2(10, 0, 0)).vertices() # shift by x+10
        """
        new = Polygon2()
        new.path = self.path.transformed(Affine2D(T.A))
        return new
    def area(self):
        """
        Area of polygon
        :return: area
        :rtype: float
        Example:
        .. runblock:: pycon
            >>> from spatialmath import Polygon2
            >>> p = Polygon2([[1, 3, 2], [2, 2, 4]])
            >>> p.area()
        .. warning:: For a polygon with clockwise ordering of vertices the 
            area will be negative.
        :seealso: :meth:`moment`
        """
        return self.moment(0, 0)
    def centroid(self):
        """
        Centroid of polygon
        :return: centroid
        :rtype: ndarray(2)
        Example:
        .. runblock:: pycon
            >>> from spatialmath import Polygon2
            >>> p = Polygon2([[1, 3, 2], [2, 2, 4]])
            >>> p.centroid()
        :seealso: :meth:`moment`
        """
        return np.r_[self.moment(1, 0), self.moment(0, 1)] / self.moment(0, 0)
    def vertices(self, closed=False):
        """
        Vertices of polygon
        :param closed: include first vertex twice, defaults to False
        :type closed: bool, optional
        :return: vertices
        :rtype: ndarray(2,n)
        Returns the set of vertices.  If ``closed`` is True then the last
        column is the same as the first, that is, the polygon is explicitly
        closed.
        Example:
        .. runblock:: pycon
            >>> from spatialmath import Polygon2
            >>> p = Polygon2([[1, 3, 2], [2, 2, 4]])
            >>> p.vertices()
            >>> p.vertices(closed=True)
        """
        if closed:
            vertices = self.path.vertices
            vertices = np.vstack([vertices, vertices[0, :]])
            return vertices.T
        else:
            return self.path.vertices.T
    def edges(self):
        """
        Iterate over polygon edge segments
        Creates an iterator that returns pairs of points representing the
        end points of each segment.
        """
        vertices = self.vertices(closed=True)
        for i in range(len(self)):
            yield(vertices[:, i], vertices[:, i+1])
    def moment(self, p, q):
        r"""
        Moments of polygon
        :param p: moment order x
        :type p: int
        :param q: moment order y
        :type q: int
        Returns the pq'th moment of the polygon
        .. math::
            M(p, q) = \sum_{i=0}^{n-1} x_i^p y_i^q
        Example:
        .. runblock:: pycon
            >>> from spatialmath import Polygon2
            >>> p = Polygon2([[1, 3, 2], [2, 2, 4]])
            >>> p.moment(0, 0)  # area
            >>> p.moment(3, 0)
        """
        def combin(n, r):
            # compute number of combinations of size r from set n
            def prod(values):
                    return reduce(lambda x, y: x * y, values)
                except TypeError:
                    return 1
            return prod(range(n - r + 1, n + 1)) / prod(range(1, r + 1))
        vertices = self.vertices(closed=True)
        x = vertices[0, :]
        y = vertices[1, :]
        n = len(x)
        for l in range(n):
            l1 = (l - 1) % n
            dxl = x[l] - x[l1]
            dyl = y[l] - y[l1]
            Al = x[l] * dyl - y[l] * dxl
            for i in range(p + 1):
                for j in range(q + 1):
                    s += (-1)**(i + j) \
                        * combin(p, i) \
                        * combin(q, j) / ( i+ j + 1) \
                        * x[l]**(p - i) * y[l]**(q - j) \
                        * dxl**i * dyl**j
            m += Al * s
        return m / (p + q + 2)
class Line2:
    Class to represent 2D lines
    The internal representation is in homogeneous format
    .. math::
            ax + by + c = 0
    def __init__(self, line):
        self.line = base.getvector(line, 3)
    @classmethod
    def TwoPoints(self, p1, p2):
        """
        Create 2D line from two points
        :param p1: point on the line
        :type p1: array_like(2) or array_like(3)
        :param p2: another point on the line
        :type p2: array_like(2) or array_like(3)
        The points can be given in Euclidean or homogeneous form.
        """
        p1 = base.getvector(p1)
        if len(p1) == 2:
            p1 = np.r_[p1, 1]
        p2 = base.getvector(p2)
        if len(p2) == 2:
            p2 = np.r_[p2, 1]
        return Line2(np.cross(p1, p2))
    @classmethod
    def General(self, m, c):
        """
        Create line from general line
        :param m: line gradient
        :type m: float
        :param c: line intercept
        :type c: float
        :return: a 2D line
        :rtype: a Line2 instance
        Creates a line from the parameters of the general line :math:`y = mx + c`.
        .. note:: A vertical line cannot be represented.
        """
        return Line2([m, -1, c])
    def general(self):
        r"""
        Parameters of general line
        :return: parameters of general line (m, c)
        :rtype: ndarray(2)
        Return the parameters of a general line :math:`y = mx + c`.
        """
        return -self.line[[0, 2]] / self.line[1]
    def __str__(self):
        return f"Line2: {self.line}"
    def plot(self, **kwargs):
        """
        Plot the line using matplotlib
        :param kwargs: arguments passed to Matplotlib ``pyplot.plot``
        """
        base.plot_homline(self.line, **kwargs)
    def intersect(self, other):
        """
        Intersection with line
        :param other: another 2D line
        :type other: Line2
        :return: intersection point in homogeneous form
        :rtype: ndarray(3)
        If the lines are parallel then the third element of the returned 
        homogeneous point will be zero (an ideal point).
        """
        # return intersection of 2 lines
        # return mindist and points if no intersect
        return np.cross(self.line, other.line)
    def contains(self, p):
        """
        Test if point is in line
        :param p1: point to test
        :type p1: array_like(2) or array_like(3)
        :return: True if point lies in the line
        :rtype: bool
        """
        p = base.getvector(p)
        if len(p) == 2:
            p = np.r_[p, 1]
        return base.iszero(self.line * p)
    # variant that gives lambda
    def intersect_segment(self, p1, p2):
        """
        Test for line intersecting line segment
        :param p1: start of line segment
        :type p1: array_like(2) or array_like(3)
        :param p2: end of line segment
        :type p2: array_like(2) or array_like(3)
        :return: True if they intersect
        :rtype: bool
        Tests whether the line intersects the line segment defined by endpoints
        ``p1`` and ``p2`` which are given in Euclidean or homogeneous form.
        """
        p1 = base.getvector(p1)
        if len(p1) == 2:
            p1 = np.r_[p1, 1]
        p2 = base.getvector(p2)
        if len(p2) == 2:
            p2 = np.r_[p2, 1]
        z1 = self.line * p1
        z2 = self.line * p2
        if np.sign(z1) != np.sign(z2):
            return True
        if self.contains(p1) or self.contains(p2):
            return True
        return False
    # these should have same names as for 3d case
    def distance_line_line():
        pass
    def distance_line_point():
        pass
    def points_join():
        pass
    def intersect_polygon___line():
        pass
    def contains_polygon_point():
        pass
class LineSegment2(Line2):
    # line segment class that subclass
    # has hom line + 2 values of lambda
if __name__ == "__main__":
    p = Polygon2([[1, 3, 2], [2, 2, 4]])
    p.transformed(SE2(0, 0, np.pi/2)).vertices()
    a = Line2.TwoPoints((1,2), (7,5))
    print(a)
    p = Polygon2(np.array([[4, 4, 6, 6], [2, 1, 1, 2]]))
    base.plotvol2([8])
    p.plot(color='b', alpha=0.3)
    for theta in np.linspace(0, 2*np.pi, 100):
        p.animate(SE2(0, 0, theta))
        plt.show()
        plt.pause(0.05)
    # print(p)
    # p.plot(alpha=0.5, color='b')
    # print(p.contains([5.,5.]))
    # print(p.contains([5,1.5]))
    # print(p.contains([4, 2.1]))
    # print(p.vertices())
    # print(p.area())
    # print(p.centroid())
    # print(p.bbox())
    # print(p.radius())
    # print(p.vertices(closed=True))
    # for e in p.edges():
    #     print(e)
    # p2 = p.transformed(SE2(-5, -1.5, 0))
    # print(p2.vertices())
    # print(p2.area())
    # p2.plot(alpha=0.5, facecolor='r')
    # p.move(SE2(0, 0, 0.7))
    # plt.show(block=True)
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