环形布局外节点的螺旋Bezier路径实现需求

Networkx环形布局（双层环）示意图

需求背景 #

我有一个环形布局图，按设计要求有12个节点位于布局外侧，外侧节点的布局代码如下：

num_miR_nodes = len(miR_nodes['nodes'])
angle_increment = 2*math.pi / num_miR_nodes
miR_radius = 1.5
for i, node in enumerate(miR_nodes['nodes']):
    angle = i * angle_increment
    x = miR_radius * math.cos(angle)
    y = miR_radius * math.sin(angle)
    pos[node] = (x, y)
    G.add_node(node)

我需要为这12个外侧节点的每条直边创建Bezier路径（或类Bezier曲线），要求曲线以螺旋向内的方式延伸，在到达目标节点前始终处于布局节点外侧，避免边因过度调整中点而偏离图结构。

现有实现 #

目前仅完成了环形布局内侧边的Bezier曲线实现，代码如下：

def draw_curved_edges2(G, pos, ax, alpha):
    for u, v, d in G.edges(data=True):
        edge_color = d['edge_color']
        weight = d['width']
        pos_u = pos[u]
        pos_v = pos[v]
        
        x_u, y_u = pos_u
        x_v, y_v = pos_v

        if 'miR' not in u:
            # 边的中点
            x_mid = 0 * (x_u + x_v)
            y_mid = 0 * (y_u + y_v)
            
            # Bezier控制点
            x_ctrl = 0.25 * (x_mid + 0.5 * (x_u + x_v))
            y_ctrl = 0.25 * (y_mid + 0.5 * (y_u + y_v))
            
            # Bezier曲线路径
            bezier_path = Path([(x_u, y_u), (x_ctrl, y_ctrl), (x_v, y_v)], [Path.MOVETO, Path.CURVE3, Path.CURVE3])
            width = G[u][v]['width']# for u, v in G.edges()]
            #patch = PathPatch(bezier_path, facecolor='none', edgecolor=edge_color, linewidth=width, alpha=alpha)
            #ax.add_patch(patch)
            arrow = FancyArrowPatch(path=bezier_path, color=edge_color, linewidth=width, alpha=alpha, 
                                    arrowstyle="->, head_length=6, head_width=2, widthA=1.0, widthB=1.0, lengthA=0.4, lengthB=0.4")
            ax.add_patch(arrow)

draw_curved_edges2(G, pos, ax, alpha=0.4)

内容的提问来源于stack exchange，提问作者Austin Kunch