Question

我正在编写一个程序，以模拟从地球可见的火星的逆行运动。因此，这是地球和火星绕太阳运行的平面图。还有一条从地球到火星的直线。但是，我需要它与火星相交，并继续前进直到与x = 15线相交

另一个用户使用

向我发送了此代码

我以前的代码

import math
import matplotlib.pyplot as plt
import matplotlib.animation as animation
def _update_plot(i, fig, scat, l):
    scat.set_offsets(([math.cos(math.radians(i))*5, math.sin(math.radians(i))*5], [math.cos(math.radians(i/2))*10, math.sin(math.radians(i/2))*10], [0, 0]))
        l.set_data(([math.cos(math.radians(i))*5,math.cos(math.radians(i/2))*10],[math.sin(math.radians(i))*5,math.sin(math.radians(i/2))*10]))
    return [scat,l]

fig = plt.figure()

x = [0]
y = [0]

ax = fig.add_subplot(111)
ax.set_aspect('equal')
ax.grid(True, linestyle = '-', color = '0.10')
ax.set_xlim([-11, 11])
ax.set_ylim([-11, 11])

l, = plt.plot([],[], 'r--', zorder=1)
scat = plt.scatter(x, y, c = x, zorder=2)
scat.set_alpha(0.8)

anim = animation.FuncAnimation(fig, _update_plot, fargs = (fig, scat, l),
                           frames = 720, interval = 10)

plt.show()

另一个用户代码

def _update_plot(i, fig, scat, l):
    angle = math.radians(i)
    sun_pos = np.array([0., 0.])
    earth_pos = np.array([math.cos(angle)*5, math.sin(angle)*5])
    mars_pos = np.array([math.cos(angle / 2.) * 10, math.sin(angle / 2.) * 10])

    # compute the unit vector that points from Earth to Mars
    direction = mars_pos - earth_pos
    direction /= np.sqrt(np.dot(direction, direction))

    # find out where the line would intersect the x = 15 axis
    start_from = earth_pos
    alpha = (15 - start_from[0]) / direction[0]
    # if alpha comes out to be negative we picked the "wrong" planet
    if alpha < 0:
            start_from = mars_pos
            direction = -direction
            alpha = (15 - start_from[0]) / direction[0]
    y_line = start_from[1] + alpha * direction[1]

    # draw the planets
    scat.set_offsets((earth_pos, mars_pos, sun_pos))
    # draw the line
    l.set_data(([start_from[0], 15], [start_from[1], y_line]))
    return [scat,l]

所以目标是要有一条线从“地球”（最里面的移动物体）到x = 15线以及之间的另一条移动物体。

我还假设该行仅在该行到达x = 15时才出现，因此仅在轨道周期的第一和最后四分之一

Python动画，连接两个移动点的线并在固定线相交处停止

0 个答案: