boids_BOIDS鸟群模拟_

import sys, argparse import math import numpy as np import matplotlib.pyplot as plt import matplotlib.animation as animation from scipy.spatial.distance import squareform, pdist, cdist #计算点之间的距离 from numpy.linalg import norm from matplotlib.colors import ListedColormap import matplotlib.patches as patches width, height = 640, 480 #设置屏幕上模拟窗口的宽度和高度 class Boids: def __init__(self, N): """ initialize the Boid simulation""" #初始化位置和速度 self.pos = [width/2.0, height/2.0] + 10*np.random.rand(2*N).reshape(N, 2) #'''创建一个 numpy 数组 pos，对窗口中心加上 10 个单位以内的随机偏移。代码np.random.rand（2 * N）创建了一个一维数组，包含范围在[0，1]的 2N 个随机数。然后 reshape()调用将它转换成二维数组的形状（N，2），它将用于保存类鸟群个体的位置。''' # normalized random velocities angles = 2*math.pi*np.random.rand(N) self.vel = np.array(list(zip(np.sin(angles), np.cos(angles)))) self.N = N #生成一个数组，包含 N 个随机角度，范围在[0, 2pi]， # min dist of approach self.minDist = 25.0 # max magnitude of velocities calculated by "rules" self.maxRuleVel = 0.03 # max maginitude of final velocity self.maxVel = 2.0 def tick(self, frameNum, pts, beak): """Update the simulation by one time step.""" self.distMatrix = squareform(pdist(self.pos)) #用 squareform()和 pdist()方法来计算一组点之间两两的距离 # apply rules: self.vel += self.applyRules() self.limit(self.vel, self.maxVel) self.pos += self.vel self.applyBC() # update data pts.set_data(self.pos.reshape(2*self.N)[::2], self.pos.reshape(2*self.N)[1::2]) vec = self.pos + 10*self.vel/self.maxVel beak.set_data(vec.reshape(2*self.N)[::2], vec.reshape(2*self.N)[1::2]) def limitVec(self, vec, maxVal): """limit magnitide of 2D vector""" mag = norm(vec) if mag > maxVal: vec[0], vec[1] = vec[0]*maxVal/mag, vec[1]*maxVal/mag def limit(self, X, maxVal): """limit magnitide of 2D vectors in array X to maxValue""" for vec in X: self.limitVec(vec, maxVal) def applyBC(self): """apply boundary conditions""" deltaR = 2.0 #该行中的deltaR提供了一个微小的缓冲区，它允许类鸟群个体开始从相反方向回来之前移出小块之外一点，从而产生更好的视觉效果 for index,coord in enumerate(self.pos): if coord[0] > width + deltaR: coord[0] = - deltaR if coord[0] < - deltaR: coord[0] = width + deltaR if coord[1] > height + deltaR: coord[1] = - deltaR if coord[1] < - deltaR: coord[1] = height + deltaR if ((coord[1]-225)**2+(coord[0]-225)**2) <=3600: self.vel[index] = -self.vel[index]*2 def applyRules(self): # apply rule #1 - Separation D = self.distMatrix < 25.0 vel = self.pos*D.sum(axis=1).reshape(self.N, 1) - D.dot(self.pos) self.limit(vel, self.maxRuleVel) # different distance threshold D = self.distMatrix < 50.0 # apply rule #2 - 列队 vel2 = D.dot(self.vel) self.limit(vel2, self.maxRuleVel) vel += vel2; # apply rule #1 - 聚集 vel3 = D.dot(self.pos) - self.pos self.limit(vel3, self.maxRuleVel) vel += vel3 return vel def buttonPress(self, event): """event handler for matplotlib button presses""" # left click - add a boid if event.button is 1: self.pos = np.concatenate((self.pos, np.array([[event.xdata, event.ydata]])), axis=0) # random velocity angles = 2*math.pi*np.random.rand(1) v = np.array(list(zip(np.sin(angles), np.cos(angles)))) self.vel = np.concatenate((self.vel, v), axis=0) #拼接 self.N += 1 # right click - scatter elif event.button is 3: # add scattering velocity self.vel += 0.1*(self.pos - np.array([[event.xdata, event.ydata]])) def tick(frameNum, pts, beak, boids): #print frameNum """update function for animation""" boids.tick(frameNum, pts, beak) return pts, beak # main() function def main(): # use sys.argv if needed print('starting boids...') parser = argparse.ArgumentParser(description="Implementing Craig Reynold's Boids...") # add arguments parser.add_argument('--num-boids', dest='N', required=False) args = parser.parse_args() # number of boids N = 50 if args.N: N = int(args.N) # create boids boids = Boids(N) # setup plot fig = plt.figure(facecolor='pink') ax = plt.axes(xlim=(0, width), ylim=(0, height),facecolor='lightskyblue') ax.add_patch(patches.Rectangle((200, 200),50,50,linewidth=1,edgecolor='b',facecolor='b')) pts, = ax.plot([], [], markersize=10, c='k', marker='o', ls='None') beak, = ax.plot([], [], markersize=4, c='r', marker='o', ls='None') anim = animation.FuncAnimation(fig, tick, fargs=(pts, beak, boids), interval=50) # add a "button press" event handler cid = fig.canvas.mpl_connect('button_press_event', boids.buttonPress) plt.show() # call main if __name__ == '__main__': main()