Add functions to an Opengl point cloud viewer

I want to modify this project https://github.com/cgtuebingen/pointcloud-viewer point cloud viewer. I want to add a button. I will fix a viewing point and click the button. Upon that We need to make the current viewing point as 0,0,0 and update other points accordingly. Then these pints are passed to a python script(you can write a dummy script). It will return another set of points and show it in the viewer.