I’m not sure if that’s helpful:
Because three.js disassembled rectangles into two triangles, I have formed a center point and realized a decomposition into four triangles. Thus, the rectangles are “spatially”.
When I read this question, I thought to simulate quad. For this I have the vertices simply horizontally and vertically connected to a line.
This works with Geometry, indexed and non-indexed BufferGeometry.
See http://sandbox.threejs.hofk.de/ (only firefox), http://sandbox.threejs.hofk.de/examplesTHREEf%20r86.html
https://github.com/hofk/THREEf.js/blob/master/THREEf.js lines Geometry: 300, 2358, BufferGeometry: indexed: 580, 2570 , non indexed 1303, 2945
See also Addon. Produces almost infinite many time-varying geometries with functions