下面是一个使用Python和matplotlib库的示例代码，用于实现保持弧长的同时将其拉直的立方贝塞尔路径：

import matplotlib.pyplot as plt
import numpy as np
from scipy.special import comb

def bezier_curve(points, num_samples):
    n = len(points) - 1
    t = np.linspace(0, 1, num_samples)
    curve = np.zeros((num_samples, 2))
    
    for i in range(num_samples):
        for j in range(n+1):
            curve[i] += comb(n, j) * (1-t[i])**(n-j) * t[i]**j * points[j]
    
    return curve

def straighten_curve(curve, num_samples):
    curve_length = np.sum(np.sqrt(np.sum(np.diff(curve, axis=0)**2, axis=1)))
    sample_distances = np.linspace(0, curve_length, num_samples)
    new_curve = np.zeros((num_samples, 2))
    
    current_distance = 0
    current_point_index = 0
    for i in range(num_samples):
        while current_distance < sample_distances[i]:
            current_distance += np.sqrt(np.sum((curve[current_point_index+1] - curve[current_point_index])**2))
            current_point_index += 1
        alpha = (current_distance - sample_distances[i]) / np.sqrt(np.sum((curve[current_point_index] - curve[current_point_index-1])**2))
        new_curve[i] = curve[current_point_index-1] + alpha * (curve[current_point_index] - curve[current_point_index-1])
    
    return new_curve

# 定义控制点
points = np.array([[1, 1], [2, 3], [4, 2], [5, 4]])

# 生成贝塞尔曲线
num_samples = 100
curve = bezier_curve(points, num_samples)

# 拉直曲线
straightened_curve = straighten_curve(curve, num_samples)

# 绘制结果
plt.figure(figsize=(8, 6))
plt.plot(curve[:, 0], curve[:, 1], 'b-', label='Original Curve')
plt.plot(straightened_curve[:, 0], straightened_curve[:, 1], 'r--', label='Straightened Curve')
plt.scatter(points[:, 0], points[:, 1], color='black', label='Control Points')
plt.legend()
plt.axis('equal')
plt.show()

在上面的代码中，我们首先定义了一组控制点points，然后使用bezier_curve函数生成了一个立方贝塞尔曲线curve。接下来，我们使用straighten_curve函数将曲线拉直，生成新的曲线straightened_curve。最后，我们使用matplotlib库将原始曲线、拉直曲线和控制点绘制在图形中。

希望这个示例能够帮到你！