oxideav-mesh3d 0.0.2

Pure-Rust 3D scene + mesh typed model — Decoder/Encoder traits for STL/OBJ/glTF/FBX/USD format crates
Documentation 
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

//! Transform Matrix ↔ TRS conversion round-trips.

use oxideav_mesh3d::Transform;

const TOL: f32 = 1e-5;

fn approx_eq(a: f32, b: f32, tol: f32) -> bool {
    (a - b).abs() <= tol + tol * a.abs().max(b.abs())
}

fn quat_close(a: [f32; 4], b: [f32; 4]) -> bool {
    // Quaternions are double-cover: `q` and `-q` represent the same rotation.
    let same = a.iter().zip(b.iter()).all(|(x, y)| approx_eq(*x, *y, TOL));
    let neg = a.iter().zip(b.iter()).all(|(x, y)| approx_eq(*x, -*y, TOL));
    same || neg
}

#[test]
fn identity_round_trips() {
    let id = Transform::identity();
    let m = id.to_matrix();
    let back = Transform::from_matrix(m);
    let Transform::Trs {
        translation,
        rotation,
        scale,
    } = back
    else {
        panic!("expected TRS");
    };
    assert!(translation.iter().all(|c| approx_eq(*c, 0.0, TOL)));
    assert!(scale.iter().all(|c| approx_eq(*c, 1.0, TOL)));
    assert!(quat_close(rotation, [0.0, 0.0, 0.0, 1.0]));
}

#[test]
fn pure_translation_round_trips() {
    let trs = Transform::Trs {
        translation: [1.5, -2.25, 3.0],
        rotation: [0.0, 0.0, 0.0, 1.0],
        scale: [1.0, 1.0, 1.0],
    };
    let m = trs.to_matrix();
    assert!(approx_eq(m[0][3], 1.5, TOL));
    assert!(approx_eq(m[1][3], -2.25, TOL));
    assert!(approx_eq(m[2][3], 3.0, TOL));

    let back = Transform::from_matrix(m);
    let Transform::Trs {
        translation,
        rotation,
        scale,
    } = back
    else {
        panic!("expected TRS");
    };
    assert!(approx_eq(translation[0], 1.5, TOL));
    assert!(approx_eq(translation[1], -2.25, TOL));
    assert!(approx_eq(translation[2], 3.0, TOL));
    assert!(scale.iter().all(|c| approx_eq(*c, 1.0, TOL)));
    assert!(quat_close(rotation, [0.0, 0.0, 0.0, 1.0]));
}

#[test]
fn pure_scale_round_trips() {
    let trs = Transform::Trs {
        translation: [0.0; 3],
        rotation: [0.0, 0.0, 0.0, 1.0],
        scale: [2.0, 3.0, 0.5],
    };
    let m = trs.to_matrix();
    let back = Transform::from_matrix(m);
    let Transform::Trs { scale, .. } = back else {
        panic!("expected TRS");
    };
    assert!(approx_eq(scale[0], 2.0, TOL));
    assert!(approx_eq(scale[1], 3.0, TOL));
    assert!(approx_eq(scale[2], 0.5, TOL));
}

#[test]
fn rotation_around_y_round_trips() {
    // 90 degrees about Y. Quaternion = (0, sin(45), 0, cos(45)).
    let half_pi = std::f32::consts::FRAC_PI_2;
    let s = (half_pi / 2.0).sin();
    let c = (half_pi / 2.0).cos();
    let trs_in = Transform::Trs {
        translation: [0.5, 0.0, -1.0],
        rotation: [0.0, s, 0.0, c],
        scale: [1.0, 1.0, 1.0],
    };
    let m = trs_in.to_matrix();
    let back = Transform::from_matrix(m);
    let Transform::Trs {
        translation,
        rotation,
        scale,
    } = back
    else {
        panic!("expected TRS");
    };
    assert!(quat_close(rotation, [0.0, s, 0.0, c]));
    assert!(approx_eq(translation[0], 0.5, TOL));
    assert!(approx_eq(translation[2], -1.0, TOL));
    assert!(scale.iter().all(|c| approx_eq(*c, 1.0, TOL)));
}

#[test]
fn combined_trs_round_trips() {
    // Arbitrary rotation about (1,2,3), normalised; non-uniform scale; non-zero T.
    let axis = {
        let v = [1.0_f32, 2.0, 3.0];
        let l = (v[0] * v[0] + v[1] * v[1] + v[2] * v[2]).sqrt();
        [v[0] / l, v[1] / l, v[2] / l]
    };
    let theta = 1.2_f32;
    let s = (theta / 2.0).sin();
    let q = [axis[0] * s, axis[1] * s, axis[2] * s, (theta / 2.0).cos()];
    let original = Transform::Trs {
        translation: [4.0, -1.5, 0.25],
        rotation: q,
        scale: [1.5, 2.0, 0.75],
    };
    let m = original.to_matrix();
    let back = Transform::from_matrix(m);
    let m2 = back.to_matrix();
    // Re-encoding to a matrix and comparing avoids the quaternion
    // double-cover ambiguity entirely.
    for i in 0..4 {
        for j in 0..4 {
            assert!(
                approx_eq(m[i][j], m2[i][j], TOL),
                "mismatch at [{i}][{j}]: {} vs {}",
                m[i][j],
                m2[i][j]
            );
        }
    }
}

#[test]
fn matrix_variant_to_matrix_is_identity_passthrough() {
    let m = [
        [1.0, 0.0, 0.0, 5.0],
        [0.0, 1.0, 0.0, 6.0],
        [0.0, 0.0, 1.0, 7.0],
        [0.0, 0.0, 0.0, 1.0],
    ];
    let t = Transform::Matrix(m);
    let m2 = t.to_matrix();
    assert_eq!(m, m2);
}