Hello and welcome to my flat shaded ground demo.
So if you want to make a dynamic ground that is flat shaded using the convertToFlatShadedMesh function would make it a 2 step process so i made my own custom mesh builder that also flips the triangles to give a better effect.
DEMO http://www.babylonjs-playground.com/#1SLLOJ#77
how to - Equilateral Triangles http://www.babylonjs-playground.com/#ANEKM#8 //this is not dynamic look at demo to see how to edit equilateral triangles
how to - Right Triangles http://www.babylonjs-playground.com/#ANEKM#6