bram32 on codersworkshop was able to shed some light on the problem.
To set the u# and v# of each vertex, you should use VertexTexCoords.
v1=AddVertex(Surf,4,0,GraphLoop,0,1,0) ; create vertex on horiz plane
v2=AddVertex(Surf,4,GraphValues(GraphLoop),tempy,0,0,0) ; create vertex at y-value
vertextexcoords Surf, v1, 0, float(graphloop) / float(numxvalues)
vertextexcoords Surf, v2, 1, float(graphloop) / float(numxvalues)
A little bit of tweaking and it was working a treat!
To set the u# and v# of each vertex, you should use VertexTexCoords.
v1=AddVertex(Surf,4,0,GraphLoop,0,1,0) ; create vertex on horiz plane
v2=AddVertex(Surf,4,GraphValues(GraphLoop),tempy,0,0,0) ; create vertex at y-value
vertextexcoords Surf, v1, 0, float(graphloop) / float(numxvalues)
vertextexcoords Surf, v2, 1, float(graphloop) / float(numxvalues)
A little bit of tweaking and it was working a treat!