how to draw part of a cone in rgl?

Question

I would like to use rgl to draw part of a cone, as on this web page (click "3d cone model")

I would like to specify three parameters (bottom radius, top radius, height) then draw a cone in rgl -- is this possible/easy? how? I don't see any mention of drawing cones in the rgl docs.

Answer 1

The cylinder3d function can do that. You specify two points (the center of the top and bottom), and the two radii. For example,

pts <- cbind(c(0, 0), c(0, 1), c(0, 0))   # the centers
radii <- c(0.2, 0.4)
cone <- cylinder3d(pts, radii, sides = 64)
shade3d(cone, col = "lightblue")