I'm looking for a way to draw 3D surfaces in LaTeX with triangles on them to show the sum of angles being >, =, or < 180 degrees, exactly as in this photo

(source: space.com)
.
I'd just like to do it myself, but I'm rather overwhelmed by the array of options available, and not sure where to start (nor how to do it). Thank you.
graphicxpackage? Or even just include this picture? – Thruston Dec 30 '15 at 17:54