oxihuman-mesh 0.2.1

Mesh processing, topology, and geometry algorithms for OxiHuman
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

// Copyright (C) 2026 COOLJAPAN OU (Team KitaSan)
// SPDX-License-Identifier: Apache-2.0
#![allow(dead_code)]

//! Mesh surface area measurement.

#[allow(dead_code)]
pub fn am_triangle_area(a: [f32; 3], b: [f32; 3], c: [f32; 3]) -> f32 {
    let ab = [b[0] - a[0], b[1] - a[1], b[2] - a[2]];
    let ac = [c[0] - a[0], c[1] - a[1], c[2] - a[2]];
    let cx = ab[1] * ac[2] - ab[2] * ac[1];
    let cy = ab[2] * ac[0] - ab[0] * ac[2];
    let cz = ab[0] * ac[1] - ab[1] * ac[0];
    (cx * cx + cy * cy + cz * cz).sqrt() / 2.0
}

#[allow(dead_code)]
pub fn am_total_area(positions: &[[f32; 3]], indices: &[[u32; 3]]) -> f32 {
    am_face_areas(positions, indices).iter().sum()
}

#[allow(dead_code)]
pub fn am_face_areas(positions: &[[f32; 3]], indices: &[[u32; 3]]) -> Vec<f32> {
    indices.iter().map(|tri| {
        let a = tri[0] as usize;
        let b = tri[1] as usize;
        let c = tri[2] as usize;
        if a < positions.len() && b < positions.len() && c < positions.len() {
            am_triangle_area(positions[a], positions[b], positions[c])
        } else {
            0.0
        }
    }).collect()
}

#[allow(dead_code)]
pub fn am_largest_face(positions: &[[f32; 3]], indices: &[[u32; 3]]) -> Option<usize> {
    let areas = am_face_areas(positions, indices);
    if areas.is_empty() { return None; }
    let mut max_i = 0;
    let mut max_a = areas[0];
    for (i, &a) in areas.iter().enumerate() {
        if a > max_a { max_a = a; max_i = i; }
    }
    Some(max_i)
}

#[allow(dead_code)]
pub fn am_smallest_face(positions: &[[f32; 3]], indices: &[[u32; 3]]) -> Option<usize> {
    let areas = am_face_areas(positions, indices);
    if areas.is_empty() { return None; }
    let mut min_i = 0;
    let mut min_a = areas[0];
    for (i, &a) in areas.iter().enumerate() {
        if a < min_a { min_a = a; min_i = i; }
    }
    Some(min_i)
}

#[allow(dead_code)]
pub fn am_area_variance(positions: &[[f32; 3]], indices: &[[u32; 3]]) -> f32 {
    let areas = am_face_areas(positions, indices);
    let n = areas.len();
    if n == 0 { return 0.0; }
    let mean = areas.iter().sum::<f32>() / n as f32;
    areas.iter().map(|&a| (a - mean) * (a - mean)).sum::<f32>() / n as f32
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn test_unit_right_triangle_area() {
        let area = am_triangle_area([0.0, 0.0, 0.0], [1.0, 0.0, 0.0], [0.0, 1.0, 0.0]);
        assert!((area - 0.5).abs() < 1e-5);
    }

    #[test]
    fn test_total_area_two_triangles() {
        let positions = vec![[0.0, 0.0, 0.0], [1.0, 0.0, 0.0], [0.0, 1.0, 0.0], [1.0, 1.0, 0.0]];
        let indices = vec![[0u32, 1, 2], [1, 3, 2]];
        let total = am_total_area(&positions, &indices);
        assert!((total - 1.0).abs() < 1e-4);
    }

    #[test]
    fn test_face_areas_count() {
        let positions = vec![[0.0, 0.0, 0.0], [1.0, 0.0, 0.0], [0.0, 1.0, 0.0]];
        let indices = vec![[0u32, 1, 2]];
        let areas = am_face_areas(&positions, &indices);
        assert_eq!(areas.len(), 1);
    }

    #[test]
    fn test_largest_face() {
        let positions = vec![
            [0.0, 0.0, 0.0], [1.0, 0.0, 0.0], [0.0, 1.0, 0.0],
            [0.0, 0.0, 0.0], [10.0, 0.0, 0.0], [0.0, 10.0, 0.0],
        ];
        let indices = vec![[0u32, 1, 2], [3, 4, 5]];
        assert_eq!(am_largest_face(&positions, &indices), Some(1));
    }

    #[test]
    fn test_smallest_face() {
        let positions = vec![
            [0.0, 0.0, 0.0], [1.0, 0.0, 0.0], [0.0, 1.0, 0.0],
            [0.0, 0.0, 0.0], [10.0, 0.0, 0.0], [0.0, 10.0, 0.0],
        ];
        let indices = vec![[0u32, 1, 2], [3, 4, 5]];
        assert_eq!(am_smallest_face(&positions, &indices), Some(0));
    }

    #[test]
    fn test_largest_empty() {
        assert_eq!(am_largest_face(&[], &[]), None);
    }

    #[test]
    fn test_area_variance_uniform() {
        let positions = vec![[0.0, 0.0, 0.0], [1.0, 0.0, 0.0], [0.0, 1.0, 0.0]];
        let indices = vec![[0u32, 1, 2], [0, 1, 2]];
        let var = am_area_variance(&positions, &indices);
        assert!(var < 1e-5);
    }

    #[test]
    fn test_area_variance_empty() {
        assert_eq!(am_area_variance(&[], &[]), 0.0);
    }
}