oxihuman-mesh 0.2.0

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
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
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187

//! Compute morphed normals from delta vertices.
#![allow(dead_code)]

/// Result of a morph normal computation.
#[allow(dead_code)]
pub struct MorphNormalResult {
    pub normals: Vec<[f32; 3]>,
    pub vertex_count: usize,
}

fn normalize3(v: [f32; 3]) -> [f32; 3] {
    let len = (v[0]*v[0] + v[1]*v[1] + v[2]*v[2]).sqrt();
    if len < 1e-10 { [0.0, 0.0, 1.0] } else { [v[0]/len, v[1]/len, v[2]/len] }
}

fn cross3(a: [f32; 3], b: [f32; 3]) -> [f32; 3] {
    [
        a[1]*b[2] - a[2]*b[1],
        a[2]*b[0] - a[0]*b[2],
        a[0]*b[1] - a[1]*b[0],
    ]
}

/// Compute normals for morphed positions given base positions + delta and triangle indices.
#[allow(dead_code)]
pub fn compute_morph_normals(
    positions: &[[f32; 3]],
    deltas: &[[f32; 3]],
    indices: &[u32],
) -> MorphNormalResult {
    let n = positions.len();
    let morphed: Vec<[f32; 3]> = positions.iter().zip(deltas.iter())
        .map(|(p, d)| [p[0]+d[0], p[1]+d[1], p[2]+d[2]])
        .collect();
    let normals = recompute_normals_from_positions(&morphed, indices);
    MorphNormalResult { vertex_count: n, normals }
}

/// Compute per-vertex normal deltas between two normal arrays.
#[allow(dead_code)]
pub fn morph_normal_delta(base: &[[f32; 3]], morphed: &[[f32; 3]]) -> Vec<[f32; 3]> {
    base.iter().zip(morphed.iter())
        .map(|(b, m)| [m[0]-b[0], m[1]-b[1], m[2]-b[2]])
        .collect()
}

/// Apply normal morph: add delta normals to base normals and renormalize.
#[allow(dead_code)]
pub fn apply_normal_morph(base: &[[f32; 3]], deltas: &[[f32; 3]], weight: f32) -> Vec<[f32; 3]> {
    base.iter().zip(deltas.iter())
        .map(|(b, d)| normalize3([b[0]+d[0]*weight, b[1]+d[1]*weight, b[2]+d[2]*weight]))
        .collect()
}

/// Normalize a list of morph normals in place.
#[allow(dead_code)]
pub fn normalize_morph_normals(normals: &[[f32; 3]]) -> Vec<[f32; 3]> {
    normals.iter().map(|n| normalize3(*n)).collect()
}

/// Smooth morph normals by averaging with neighbors (simple Laplacian over index pairs).
#[allow(dead_code)]
pub fn morph_normal_smooth(normals: &[[f32; 3]], iterations: usize) -> Vec<[f32; 3]> {
    let mut current = normals.to_vec();
    for _ in 0..iterations {
        let prev = current.clone();
        let n = prev.len();
        if n < 2 { break; }
        for i in 0..n {
            let left = if i == 0 { n - 1 } else { i - 1 };
            let right = (i + 1) % n;
            let nx = (prev[left][0] + prev[i][0] + prev[right][0]) / 3.0;
            let ny = (prev[left][1] + prev[i][1] + prev[right][1]) / 3.0;
            let nz = (prev[left][2] + prev[i][2] + prev[right][2]) / 3.0;
            current[i] = normalize3([nx, ny, nz]);
        }
    }
    current
}

/// Recompute normals from positions and triangle indices.
#[allow(dead_code)]
pub fn recompute_normals_from_positions(positions: &[[f32; 3]], indices: &[u32]) -> Vec<[f32; 3]> {
    let n = positions.len();
    let mut acc = vec![[0.0f32; 3]; n];
    let tri_count = indices.len() / 3;
    for t in 0..tri_count {
        let i0 = indices[t*3] as usize;
        let i1 = indices[t*3+1] as usize;
        let i2 = indices[t*3+2] as usize;
        if i0 >= n || i1 >= n || i2 >= n { continue; }
        let p0 = positions[i0];
        let p1 = positions[i1];
        let p2 = positions[i2];
        let e1 = [p1[0]-p0[0], p1[1]-p0[1], p1[2]-p0[2]];
        let e2 = [p2[0]-p0[0], p2[1]-p0[1], p2[2]-p0[2]];
        let fn_ = cross3(e1, e2);
        for &idx in &[i0, i1, i2] {
            acc[idx][0] += fn_[0];
            acc[idx][1] += fn_[1];
            acc[idx][2] += fn_[2];
        }
    }
    acc.iter().map(|n| normalize3(*n)).collect()
}

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

    #[test]
    fn test_recompute_normals_plane() {
        let pos = vec![[0.0f32,0.0,0.0],[1.0,0.0,0.0],[0.0,1.0,0.0],[1.0,1.0,0.0]];
        let idx = vec![0u32,1,2, 1,3,2];
        let normals = recompute_normals_from_positions(&pos, &idx);
        assert_eq!(normals.len(), 4);
        for n in &normals {
            assert!((n[2].abs() - 1.0).abs() < 1e-4, "normal z should be 1: {:?}", n);
        }
    }

    #[test]
    fn test_morph_normal_delta_zero() {
        let a = vec![[0.0f32,0.0,1.0],[0.0,1.0,0.0]];
        let d = morph_normal_delta(&a, &a);
        for dd in &d { assert!(dd[0].abs() < 1e-6); }
    }

    #[test]
    fn test_apply_normal_morph_zero_weight() {
        let base = vec![[0.0f32,0.0,1.0]];
        let delta = vec![[0.0f32,1.0,0.0]];
        let r = apply_normal_morph(&base, &delta, 0.0);
        assert!((r[0][2] - 1.0).abs() < 1e-5);
    }

    #[test]
    fn test_normalize_morph_normals_unit() {
        let ns = vec![[3.0f32,0.0,0.0],[0.0,2.0,0.0]];
        let r = normalize_morph_normals(&ns);
        for n in &r {
            let l = (n[0]*n[0]+n[1]*n[1]+n[2]*n[2]).sqrt();
            assert!((l-1.0).abs() < 1e-5);
        }
    }

    #[test]
    fn test_morph_normal_smooth_count() {
        let ns = vec![[1.0f32,0.0,0.0],[0.0,1.0,0.0],[0.0,0.0,1.0]];
        let r = morph_normal_smooth(&ns, 2);
        assert_eq!(r.len(), 3);
    }

    #[test]
    fn test_compute_morph_normals_count() {
        let pos = vec![[0.0f32,0.0,0.0],[1.0,0.0,0.0],[0.0,1.0,0.0]];
        let deltas = vec![[0.0f32;3];3];
        let idx = vec![0u32,1,2];
        let r = compute_morph_normals(&pos, &deltas, &idx);
        assert_eq!(r.vertex_count, 3);
    }

    #[test]
    fn test_morph_normal_result_vertex_count() {
        let r = MorphNormalResult { normals: vec![[0.0,0.0,1.0]], vertex_count: 1 };
        assert_eq!(r.vertex_count, 1);
    }

    #[test]
    fn test_morph_normal_smooth_normalized() {
        let ns = vec![[1.0f32,0.0,0.0],[0.0,1.0,0.0],[0.0,0.0,1.0]];
        let r = morph_normal_smooth(&ns, 1);
        for n in &r {
            let l = (n[0]*n[0]+n[1]*n[1]+n[2]*n[2]).sqrt();
            assert!((l-1.0).abs() < 1e-4);
        }
    }

    #[test]
    fn test_apply_morph_unit_result() {
        let base = vec![[1.0f32,0.0,0.0]];
        let delta = vec![[0.0f32,0.0,0.0]];
        let r = apply_normal_morph(&base, &delta, 1.0);
        let l = (r[0][0]*r[0][0]+r[0][1]*r[0][1]+r[0][2]*r[0][2]).sqrt();
        assert!((l-1.0).abs() < 1e-5);
    }
}