Odd rendering issue -- Extra lines When I render one of my models in my app, black lines (which I did not draw) are getting rendered which run from various points on my model all to a single point.  Please see image.  As I move my camera around in the app, the single point moves around (and in turn the destination of the lines).  What are these black lines, what are they pointing to, and how do I fix?  







Note: Blender newbie here

Thanks

Edit new photo showing mesh issues in blender too.  Removed reference to libgdx to remove confusion.
Welp, I didn't determine the exact issue for all situations, but it seemed some meshes had doubles issues, faces issues, normals issues, etc.  You could do things like select a vertex around a bad area and hit Ctrl+ to select similar ones, but the bad one wouldn't get selected.

To fix, I ended up selecting whole areas that were at issue and deleting them.  I then either rebuilt them or duplicated other similar areas and placing them there.

I hate not knowing the exact issue, but at least I'm up and running.  

Thanks to those who took the time!