If I am looking straight onto a triangular face then is there a straightforward way to know the order of the indices as stored by faceVertexUv arrays ? Thanks for any help.
Your question seems a bit unclear to me (sorry). You can retrieve the indices of a face (a,b,c) from Geometry.faces. The entries in faceVertexUv just represent the texture coordinates for each index (a,b,c).
Sorry not to be clear …
So in a statement like:
geom2.faceVertexUvs[0][0][1].x = 1.0;
the “1” on the left handside is the index designating the vertex as originally set up with index 1 in the Geometry.faces structure . It’s that simple ?