VNF textures have triangulation artifacts

[adrianVmariano]

cyl(d=10/PI, h=5, chamfer=0,
       texture=texture("hex_grid"), tex_samples=2, tex_reps=[6,3], tex_depth=.2);

[revarbat]

This will almost certainly be a bug in the VNF slicing function.

[adrianVmariano]

The artifacts arise due to application of vnf_slice to an already triangulated VNF. The solution (verified) is to make all the texture VNFs untriangulated. For the bricks_vnf texture

                [0,4,7,20], [4,8,11,7], [9,8,4,5], [4,0,1,5], [10,9,5,6],
                [20,7,6,13,12,21] ,[2,3,23,22,15,14],
                [15,19,18,14], [22,23,27,26], [16,19,15,12],[13,6,5,1],
                [26,25,21,22], [8,9,10,11],[7,11,10,6],[17,16,12,13],[22,21,12,15],[16,17,18,19],[24,25,26,27],[25,24,20,21]

is the correct face set.

[adrianVmariano]

Two things could still be improved here. I tried creating a single-polygon background field for cone and it runs into trouble slicing it. If this worked it would produce the fewest artifacts.

We could sample cone and other shapes on a grid instead of on their natural triangulation. I believe that would produce a better result.

We could at least for straight cylinders, not apply slicing in the Y direction, which would reduce the number of artifacts.