off-rs - A simple .off file parser

Parses .off (Object File Format) files. This implementation follows this spec from the Princeton Shape Benchmark.

Sample .off file:

```off

this file header has to be the first instruction

OFF

cube.off

A cube

8 vertices, 6 faces, 12 edges

8 6 12

vetex coordinates: x, y, z

1.632993 0.000000 1.154701 0.000000 1.632993 1.154701 -1.632993 0.000000 1.154701 0.000000 -1.632993 1.154701 1.632993 0.000000 -1.154701 0.000000 1.632993 -1.154701 -1.632993 0.000000 -1.154701 0.000000 -1.632993 -1.154701

face indicies & RGBA color data: n, v1, v2, v3, v4, r, g, b, a

4 0 1 2 3 1.000 0.000 0.000 0.75 4 7 4 0 3 0.300 0.400 0.000 0.75 4 4 5 1 0 0.200 0.500 0.100 0.75 4 5 6 2 1 0.100 0.600 0.200 0.75 4 3 2 6 7 0.000 0.700 0.300 0.75 4 6 5 4 7 0.000 1.000 0.000 0.75 ```

This cube.off file is parsed using off-rs in this example.

Usage

```rust let off_string = r#" OFF 3 1 1.0 0.0 0.0 0.0 1.0 0.0 0.0 0.0 1.0 4 0 1 2 3 255 0 0 # red "#;

let mesh = offrs::parse( offstring, Default::default() // optional ParserOptions );

println!("{:#?}", mesh); ```

Will return a structure like this:

jsonc Mesh { vertices: [ Vertex { position: Position { x: 1.0, y: 0.0, z: 0.0, }, color: None, }, ... faces: [ Face { vertices: [ 0, 1, 2, 3, ], color: Some( Color { red: 1.0, green: 0.0, blue: 0.0, alpha: 1.0, }, ), }, ...