I'n going to input some coordinates with which to build a world based on an initial triangle from the three vertices the user selects.

I can modify this triangle into a pentagon, and the pentagon into a fan of five triangles, and then build out a ring of triangles in a strip more or less around the equator, then another triangle fan around the other pole of the globe.

I have a page which takes three points from me and draws a triangle. When you click again it subdivides the triangle into a pentagon.