Got reading of GML files working. Now I need to handle coordinates and elevation:

And it works!

Need to add some lighting: docs.panda3d.org/1.10/python/programming/render-attributes/lighting

Need to add gridlines (Add method to ShapePrimitives):

prim = GeomLines(Geom.UHStatic)

prim.addVertex(0)
prim.addVertex(1)
prim.addVertex(2)
# thats the first triangle

# you can also add a few at once
prim.addVertices(2, 1, 3)

prim.addVertices(0, 5, 6)