Struct StlImporter 

pub struct StlImporter;

Imports STL files (binary or ASCII) into 3MF Model structures.

The importer supports both binary and ASCII STL formats:

• read(): Auto-detects the format using the file size formula, then dispatches to the appropriate parser. Requires Read + Seek.
• read_binary(): Explicit binary-format parser. Requires only Read.
• read_ascii(): Explicit ASCII-format parser. Requires only Read.

Vertices are deduplicated using bitwise float comparison during import.

Implementations

impl StlImporter

pub fn new() -> Self

Creates a new STL importer instance.

pub fn read<R: Read + Seek>(reader: R) -> Result<Model>

Reads an STL file, auto-detecting binary vs ASCII format.

Uses the file size formula to distinguish binary files (even those whose headers begin with “solid”) from ASCII files.

Arguments

• reader - Any type implementing Read + Seek containing STL data

Returns

A Model containing the parsed geometry. Binary STL produces a single object; ASCII STL produces one object per solid.

Errors

Returns Lib3mfError::Io if reading or seeking fails. Returns [Lib3mfError::Validation] or [Lib3mfError::InvalidStructure] if parsing fails.

pub fn read_binary<R: Read>(reader: R) -> Result<Model>

Reads a binary STL file and converts it to a 3MF Model.

Arguments

• reader - Any type implementing Read containing binary STL data

Returns

A Model containing:

• Single mesh object with ResourceId(1) named “STL Import”
• All triangles from the STL file
• Deduplicated vertices (using bitwise float comparison)
• Single build item referencing the mesh object

Errors

Returns Lib3mfError::Io if:

• Cannot read 80-byte header
• Cannot read triangle count
• Cannot read triangle data (normals, vertices, attribute bytes)

Returns Lib3mfError::Validation if triangle count field cannot be parsed.

Format Details

• Vertex deduplication: Uses HashMap with bitwise float comparison [x.to_bits(), y.to_bits(), z.to_bits()] as key. Only exactly identical vertices (bitwise) are merged.
• Normal vectors: Read from STL but ignored (not stored in Model).
• Attribute bytes: Read but ignored (2-byte field after each triangle).

Examples

use lib3mf_converters::stl::StlImporter;
use std::fs::File;

let file = File::open("cube.stl")?;
let model = StlImporter::read_binary(file)?;

// Access the imported mesh
let obj = model.resources.get_object(lib3mf_core::model::resources::ResourceId(1))
    .expect("STL import creates object with ID 1");
if let lib3mf_core::model::Geometry::Mesh(mesh) = &obj.geometry {
    println!("Imported {} vertices, {} triangles",
        mesh.vertices.len(), mesh.triangles.len());
}

pub fn read_ascii<R: Read>(reader: R) -> Result<Model>

Reads an ASCII STL file and converts it to a 3MF Model.

Parses one or more solid ... endsolid blocks. Each solid becomes a separate Object with its own ResourceId and BuildItem.

Arguments

• reader - Any type implementing Read containing ASCII STL text

Returns

A Model containing:

• One mesh object per solid, with ResourceIds starting at 1
• Object names taken from the solid name (if any)
• Deduplicated vertices per solid (using bitwise float comparison)
• One build item per solid with identity transform

Errors

Returns [Lib3mfError::Io] if reading fails. Returns [Lib3mfError::InvalidStructure] if vertex coordinates cannot be parsed.

Behavior

• Keywords are matched case-insensitively (SOLID, Facet, VERTEX, etc.)
• Solid names with spaces are supported (solid My Cool Part)
• endsolid name is not validated (may differ from solid name or be absent)
• Files that end without endsolid are handled leniently
• Normal vectors from facet normal lines are read and discarded

Trait Implementations

impl Default for StlImporter

fn default() -> Self

Returns the “default value” for a type.