Function append_mesh_with_uvs 

pub fn append_mesh_with_uvs(
    tx: &mut Transaction<'_>,
    source: &AppendSource,
    uvs: Option<&[f32]>,
) -> Result<AppendReport>

append_mesh with the source’s UVs: 2 values per source position, or None for a source without them. When both sides have UVs the result does too; otherwise it has none and AppendReport::uvs_dropped is set.

Errors

OpsError::InvalidInput for bad triangle indices or a wrong uvs length, before anything is written.