demo.py plot_trisurf

Hi Angjoo, 
I'm still trying to find a way to plot the bird demo as an interactive 3d visualization, similiar to projects like [this](https://cvl-demos.cs.nott.ac.uk/vrn/). 
Have you maybe discussed to use [plot_trisurf](https://matplotlib.org/mpl_toolkits/mplot3d/tutorial.html#tri-surface-plots) function from matplotlib in demo.py to do something similar?