autofoam 0.2.9

autofoam and related tools
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
188
189

pub fn calculate_polygon_areas(
    points: &[f64],
    connectivity: &[usize],
    offsets: &[usize],
) -> Vec<f64> {
    let mut areas = Vec::with_capacity(offsets.len());
    let mut conn_idx = 0;

    for &offset in offsets {
        let poly_indices = &connectivity[conn_idx..offset];
        conn_idx = offset;

        if poly_indices.len() < 3 {
            areas.push(0.0);
            continue;
        }

        let p0_idx = poly_indices[0] * 3;
        let p0 = (points[p0_idx], points[p0_idx + 1], points[p0_idx + 2]);
        let mut area = 0.0;

        for i in 1..(poly_indices.len() - 1) {
            let p1_idx = poly_indices[i] * 3;
            let p2_idx = poly_indices[i + 1] * 3;

            let p1 = (points[p1_idx], points[p1_idx + 1], points[p1_idx + 2]);
            let p2 = (points[p2_idx], points[p2_idx + 1], points[p2_idx + 2]);

            let v1 = (p1.0 - p0.0, p1.1 - p0.1, p1.2 - p0.2);
            let v2 = (p2.0 - p0.0, p2.1 - p0.1, p2.2 - p0.2);

            let cross = (
                v1.1 * v2.2 - v1.2 * v2.1,
                v1.2 * v2.0 - v1.0 * v2.2,
                v1.0 * v2.1 - v1.1 * v2.0,
            );

            area += 0.5 * (cross.0.powi(2) + cross.1.powi(2) + cross.2.powi(2)).sqrt();
        }
        areas.push(area);
    }

    areas
}

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

    #[test]
    fn test_triangle_area() {
        let points = vec![
            0.0, 0.0, 0.0, // vertex 0
            1.0, 0.0, 0.0, // vertex 1
            0.0, 1.0, 0.0, // vertex 2
        ];
        let connectivity = vec![0, 1, 2];
        let offsets = vec![3];

        let areas = calculate_polygon_areas(&points, &connectivity, &offsets);
        assert_eq!(areas.len(), 1);
        assert!((areas[0] - 0.5).abs() < 1e-10);
    }

    #[test]
    fn test_xnorm_square_area() {
        let points = vec![
            0.0, 0.0, 0.0, // vertex 0
            0.0, 1.0, 0.0, // vertex 1
            0.0, 1.0, 1.0, // vertex 2
            0.0, 0.0, 1.0, // vertex 3
        ];
        let connectivity = vec![0, 1, 2, 3];
        let offsets = vec![4];

        let areas = calculate_polygon_areas(&points, &connectivity, &offsets);
        assert_eq!(areas.len(), 1);
        assert!((areas[0] - 1.0).abs() < 1e-10);
    }

    #[test]
    fn test_ynorm_square_area() {
        let points = vec![
            0.0, 0.0, 0.0, // vertex 0
            0.0, 0.0, 1.0, // vertex 1
            1.0, 0.0, 1.0, // vertex 2
            1.0, 0.0, 0.0, // vertex 3
        ];
        let connectivity = vec![0, 1, 2, 3];
        let offsets = vec![4];

        let areas = calculate_polygon_areas(&points, &connectivity, &offsets);
        assert_eq!(areas.len(), 1);
        assert!((areas[0] - 1.0).abs() < 1e-10);
    }

    #[test]
    fn test_znorm_square_area() {
        let points = vec![
            0.0, 0.0, 0.0, // vertex 0
            1.0, 0.0, 0.0, // vertex 1
            1.0, 1.0, 0.0, // vertex 2
            0.0, 1.0, 0.0, // vertex 3
        ];
        let connectivity = vec![0, 1, 2, 3];
        let offsets = vec![4];

        let areas = calculate_polygon_areas(&points, &connectivity, &offsets);
        assert_eq!(areas.len(), 1);
        assert!((areas[0] - 1.0).abs() < 1e-10);
    }

    #[test]
    fn test_multiple_polygons() {
        // Two triangles
        let points = vec![
            0.0, 0.0, 0.0, // vertex 0 - first triangle, 0.5 area
            1.0, 0.0, 0.0, // vertex 1
            0.0, 1.0, 0.0, // vertex 2
            2.0, 0.0, 0.0, // vertex 3 - second triangle, 1.0 area
            4.0, 0.0, 0.0, // vertex 4
            3.0, 1.0, 0.0, // vertex 5
        ];
        let connectivity = vec![0, 1, 2, 3, 4, 5];
        let offsets = vec![3, 6];

        let areas = calculate_polygon_areas(&points, &connectivity, &offsets);
        assert_eq!(areas.len(), 2);
        assert!((areas[0] - 0.5).abs() < 1e-10);
        assert!((areas[1] - 1.0).abs() < 1e-10);
    }

    #[test]
    fn test_degenerate_polygon_less_than_3_vertices() {
        let points = vec![
            0.0, 0.0, 0.0, // vertex 0
            1.0, 0.0, 0.0, // vertex 1
        ];
        let connectivity = vec![0, 1];
        let offsets = vec![2];

        let areas = calculate_polygon_areas(&points, &connectivity, &offsets);
        assert_eq!(areas.len(), 1);
        assert_eq!(areas[0], 0.0);
    }

    #[test]
    fn test_empty_polygon() {
        let points = vec![];
        let connectivity = vec![];
        let offsets = vec![0];

        let areas = calculate_polygon_areas(&points, &connectivity, &offsets);
        assert_eq!(areas.len(), 1);
        assert_eq!(areas[0], 0.0);
    }

    #[test]
    fn test_3d_triangle() {
        let points = vec![
            0.0, 0.0, 0.0, // vertex 0
            1.0, 0.0, 1.0, // vertex 1
            0.0, 1.0, 1.0, // vertex 2
        ];
        let connectivity = vec![0, 1, 2];
        let offsets = vec![3];

        let areas = calculate_polygon_areas(&points, &connectivity, &offsets);
        assert_eq!(areas.len(), 1);
        let expected_area = (3.0_f64).sqrt() / 2.0; // area verified in blender
        assert!((areas[0] - expected_area).abs() < 1e-10);
    }

    #[test]
    fn test_collinear_points() {
        // Three collinear points should have zero area
        let points = vec![
            0.0, 0.0, 0.0, // vertex 0
            1.0, 0.0, 0.0, // vertex 1
            2.0, 0.0, 0.0, // vertex 2
        ];
        let connectivity = vec![0, 1, 2];
        let offsets = vec![3];

        let areas = calculate_polygon_areas(&points, &connectivity, &offsets);
        assert_eq!(areas.len(), 1);
        assert!(areas[0].abs() < 1e-10);
    }
}