使用OpenGL ES在现实世界中绘制一个三角形

I am very new in terms of Augmented Reality with some experience on OpenGL. I wanna draw something such as a triangle with OpenGL ES(Android or iOS, doesn't matter for the platform). The background needs to be captured by mobile's camera. Basically the result likes the Pokemon Go, via the camera you got the real world as the background and a Pokemon inserts into the real world.I am very new in terms of Augmented Reality wit