Function bridge_loops 

pub fn bridge_loops(
    tx: &mut Transaction<'_>,
    options: &BridgeOptions,
) -> Result<BridgeReport>

Stitches a tube between the two loops in options.

The first loop (smaller id) is traversed backward and the second forward; every emitted triangle uses its rim edges opposite to the rim triangles, so the strip is manifold at both rims, and the minimum-area correspondence keeps it untwisted. New diagonals must not already exist in the mesh. Either every triangle lands or nothing does.