如何在rgl中绘制圆锥体的一部分？

library(rgl)

open3d()

radius <- 1  # 圆锥体底面半径
height <- 2  # 圆锥体高度
angle <- 60  # 圆锥体的角度（以度为单位）

top_vertex <- c(0, 0, height)  # 圆锥体顶点坐标

num_points <- 100  # 底面顶点数量
base_points <- matrix(ncol = 3, nrow = num_points)
for (i in 1:num_points) {
  angle_rad <- 2 * pi * (i - 1) / num_points
  base_points[i, ] <- c(radius * cos(angle_rad), radius * sin(angle_rad), 0)
}

shade3d(triangularize(base_points), col = "blue")

for (i in 1:num_points) {
  triangle <- rbind(top_vertex, base_points[i, ], base_points[(i %% num_points) + 1, ])
  shade3d(triangle, col = "blue")
}

rgl.viewpoint(theta = 30, phi = 30, zoom = 0.8)
rgl.light(theta = -30, phi = 60)

rglwidget()