Given a node center, size, and angle, calculates the point on the node boundary. Works with various shapes.
cent_to_edge(x, y, angle, cex, cex2 = NULL, shape = "circle")List with x, y coordinates on boundary.
Node center x coordinate.
Node center y coordinate.
Angle in radians.
Node size (radius in user coordinates).
Secondary size for ellipse width (NULL for square aspect).
Node shape: "circle", "square", "ellipse", or polygon name.