1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165

//! Wavefront.

use nalgebra::{Point3, Unit, Vector3};
use std::{fs, path::Path};

use crate::geom::{Mesh, Triangle};

/// Load a mesh from a wavefront file.
#[inline]
#[must_use]
pub fn load(path: &Path) -> Mesh {
    read(
        &fs::read_to_string(path)
            .unwrap_or_else(|_| panic!("Failed to read file: {}.", path.display())),
    )
}

/// Read a Mesh from a wavefront string.
#[inline]
#[must_use]
pub fn read(s: &str) -> Mesh {
    let verts = read_vertices(s);
    let norms = read_normals(s);
    let faces = read_faces(s);

    let mut tris = Vec::with_capacity(faces.len());
    for face in faces {
        tris.push(Triangle::new(
            [verts[(face.0).0], verts[(face.0).1], verts[(face.0).2]],
            [norms[(face.1).0], norms[(face.1).1], norms[(face.1).2]],
        ));
    }
    Mesh::new(tris)
}

/// Read the vertex list from wavefront string.
#[inline]
#[must_use]
fn read_vertices(s: &str) -> Vec<Point3<f64>> {
    let vert_lines: Vec<_> = s
        .split('\n')
        .filter(|line| line.starts_with("v "))
        .collect();

    let mut verts = Vec::with_capacity(vert_lines.len());
    for line in vert_lines {
        let mut words = line.split_whitespace();
        words.next();

        let px = words
            .next()
            .expect("Missing vertex x value.")
            .parse::<f64>()
            .expect("Unable to parse f64 from string.");
        let py = words
            .next()
            .expect("Missing vertex y value.")
            .parse::<f64>()
            .expect("Unable to parse f64 from string.");
        let pz = words
            .next()
            .expect("Missing vertex z value.")
            .parse::<f64>()
            .expect("Unable to parse f64 from string.");

        verts.push(Point3::new(px, py, pz));
    }

    verts
}

/// Read the normal list from wavefront string.
#[inline]
#[must_use]
fn read_normals(s: &str) -> Vec<Unit<Vector3<f64>>> {
    let norm_lines: Vec<_> = s
        .split('\n')
        .filter(|line| line.starts_with("vn "))
        .collect();

    let mut norms = Vec::with_capacity(norm_lines.len());
    for line in norm_lines {
        let mut words = line.split_whitespace();
        words.next();

        let nx = words
            .next()
            .expect("Missing normal x value.")
            .parse::<f64>()
            .expect("Unable to parse f64 from string.");
        let ny = words
            .next()
            .expect("Missing normal y value.")
            .parse::<f64>()
            .expect("Unable to parse f64 from string.");
        let nz = words
            .next()
            .expect("Missing normal z value.")
            .parse::<f64>()
            .expect("Unable to parse f64 from string.");

        norms.push(Unit::new_normalize(Vector3::new(nx, ny, nz)));
    }

    norms
}

/// Read the face list from wavefront string.
#[allow(clippy::type_complexity)]
#[inline]
#[must_use]
fn read_faces(s: &str) -> Vec<((usize, usize, usize), (usize, usize, usize))> {
    let face_lines: Vec<_> = s
        .split('\n')
        .filter(|line| line.starts_with("f "))
        .collect();

    let mut faces = Vec::with_capacity(face_lines.len());
    for line in face_lines {
        let split_line = line.replace("//", " ");
        let mut words = split_line.split_whitespace();
        words.next();

        let fx = words
            .next()
            .expect("Missing face vertex x value.")
            .parse::<usize>()
            .expect("Unable to parse f64 from string.")
            - 1;
        let nx = words
            .next()
            .expect("Missing face normal x value.")
            .parse::<usize>()
            .expect("Unable to parse f64 from string.")
            - 1;
        let fy = words
            .next()
            .expect("Missing face vertex y value.")
            .parse::<usize>()
            .expect("Unable to parse f64 from string.")
            - 1;
        let ny = words
            .next()
            .expect("Missing face normal y value.")
            .parse::<usize>()
            .expect("Unable to parse f64 from string.")
            - 1;
        let fz = words
            .next()
            .expect("Missing face vertex z value.")
            .parse::<usize>()
            .expect("Unable to parse f64 from string.")
            - 1;
        let nz = words
            .next()
            .expect("Missing face normal z value.")
            .parse::<usize>()
            .expect("Unable to parse f64 from string.")
            - 1;

        faces.push(((fx, fy, fz), (nx, ny, nz)));
    }

    faces
}