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
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245


use crate::math::*;

///
/// A CPU-side version of a triangle mesh (for example [Mesh](crate::Mesh)).
/// Can be constructed manually or loaded via [io](crate::io)
/// or via the utility functions for generating simple triangle meshes.
///
#[derive(Default, Debug)]
pub struct CPUMesh {
    pub name: String,
    pub material_name: Option<String>,
    pub positions: Vec<f32>,
    pub indices: Option<Vec<u32>>,
    pub normals: Option<Vec<f32>>,
    pub uvs: Option<Vec<f32>>,
    pub colors: Option<Vec<u8>>
}

impl CPUMesh {
    pub fn square(size: f32) -> Self {
        let indices = vec![
            0, 1, 2, 2, 3, 0
        ];
        let halfsize = 0.5 * size;
        let positions = vec![
            -halfsize, -halfsize, 0.0,
            halfsize, -halfsize, 0.0,
            halfsize, halfsize, 0.0,
            -halfsize, halfsize, 0.0,
        ];
        let normals = vec![
            0.0, 0.0, 1.0,
            0.0, 0.0, 1.0,
            0.0, 0.0, 1.0,
            0.0, 0.0, 1.0,
        ];
        let uvs = vec![
            0.0, 0.0,
            1.0, 0.0,
            1.0, 1.0,
            0.0, 1.0
        ];
        CPUMesh {name: "square".to_string(), indices: Some(indices), positions, normals: Some(normals), uvs: Some(uvs), ..Default::default() }
    }

    pub fn circle(radius: f32, angle_subdivisions: u32) -> Self {
        let mut positions = Vec::new();
        let mut indices = Vec::new();
        let mut normals = Vec::new();
        for j in 0..angle_subdivisions {
            let angle = 2.0 * std::f32::consts::PI * j as f32 / angle_subdivisions as f32;

            positions.push(radius * angle.cos());
            positions.push(radius * angle.sin());
            positions.push(0.0);

            normals.push(0.0);
            normals.push(0.0);
            normals.push(1.0);
        }

        for j in 0..angle_subdivisions as u32 {
            indices.push(0);
            indices.push(j);
            indices.push((j+1)%angle_subdivisions as u32);
        }
        CPUMesh {name: "circle".to_string(), indices: Some(indices), positions, normals: Some(normals), ..Default::default() }
    }

    pub fn sphere(radius: f32) -> Self {
        let x = radius*0.525731112119133606f32;
        let z = radius*0.850650808352039932f32;
        let positions = vec!(
           -x, 0.0, z, x, 0.0, z, -x, 0.0, -z, x, 0.0, -z,
           0.0, z, x, 0.0, z, -x, 0.0, -z, x, 0.0, -z, -x,
           z, x, 0.0, -z, x, 0.0, z, -x, 0.0, -z, -x, 0.0
        );
        let indices = vec!(
           0,1,4, 0,4,9, 9,4,5, 4,8,5, 4,1,8,
           8,1,10, 8,10,3, 5,8,3, 5,3,2, 2,3,7,
           7,3,10, 7,10,6, 7,6,11, 11,6,0, 0,6,1,
           6,10,1, 9,11,0, 9,2,11, 9,5,2, 7,11,2
        );
        let normals = Some(compute_normals_with_indices(&indices, &positions));
        CPUMesh {name: "sphere".to_string(), indices: Some(indices), positions, normals, ..Default::default() }
    }

    pub fn cylinder(radius: f32, length: f32, angle_subdivisions: u32) -> Self
    {
        let length_subdivisions = 1;
        let mut positions = Vec::new();
        let mut indices = Vec::new();
        for i in 0..length_subdivisions +1 {
            let x = i as f32 / length_subdivisions as f32;
            for j in 0..angle_subdivisions {
                let angle = 2.0 * std::f32::consts::PI * j as f32 / angle_subdivisions as f32;

                positions.push(length * x);
                positions.push(radius * angle.cos());
                positions.push(radius * angle.sin());
            }
        }
        for i in 0..length_subdivisions as u32 {
            for j in 0..angle_subdivisions as u32 {
                indices.push(i * angle_subdivisions as u32 + j);
                indices.push(i * angle_subdivisions as u32 + (j+1)%angle_subdivisions as u32);
                indices.push((i+1) * angle_subdivisions as u32 + (j+1)%angle_subdivisions as u32);

                indices.push(i * angle_subdivisions as u32 + j);
                indices.push((i+1) * angle_subdivisions as u32 + (j+1)%angle_subdivisions as u32);
                indices.push((i+1) * angle_subdivisions as u32 + j);
            }
        }
        let normals = Some(compute_normals_with_indices(&indices, &positions));
        Self {name: "cylinder".to_string(), positions, indices: Some(indices), normals, ..Default::default()}
    }

    pub fn cone(radius: f32, length: f32, angle_subdivisions: u32) -> Self
    {
        let length_subdivisions = 1;
        let mut positions = Vec::new();
        let mut indices = Vec::new();
        for i in 0..length_subdivisions +1 {
            let x = i as f32 / length_subdivisions as f32;
            for j in 0..angle_subdivisions {
                let angle = 2.0 * std::f32::consts::PI * j as f32 / angle_subdivisions as f32;

                positions.push(length * x);
                positions.push(radius * angle.cos() * (1.0 - x));
                positions.push(radius * angle.sin() * (1.0 - x));
            }
        }
        for i in 0..length_subdivisions as u32 {
            for j in 0..angle_subdivisions as u32 {
                indices.push(i * angle_subdivisions as u32 + j);
                indices.push(i * angle_subdivisions as u32 + (j+1)%angle_subdivisions as u32);
                indices.push((i+1) * angle_subdivisions as u32 + (j+1)%angle_subdivisions as u32);

                indices.push(i * angle_subdivisions as u32 + j);
                indices.push((i+1) * angle_subdivisions as u32 + (j+1)%angle_subdivisions as u32);
                indices.push((i+1) * angle_subdivisions as u32 + j);
            }
        }
        let normals = Some(compute_normals_with_indices(&indices, &positions));
        Self {name: "cone".to_string(), positions, indices: Some(indices), normals, ..Default::default()}
    }

    pub fn arrow(radius: f32, length: f32, angle_subdivisions: u32) -> Self {
        let cylinder_length = length*0.7;
        let mut arrow = Self::cylinder(radius*0.5, cylinder_length, angle_subdivisions);
        arrow.name = "arrow".to_string();
        let mut cone = Self::cone(radius, length - cylinder_length, angle_subdivisions);
        for i in 0..cone.positions.len()/3 {
            cone.positions[i*3] += cylinder_length;
        }
        let offset = *arrow.indices.as_ref().unwrap().iter().max().unwrap()+1;
        arrow.indices.as_mut().unwrap().extend(cone.indices.as_ref().unwrap().iter().map(|i| i+offset));
        arrow.positions.extend(cone.positions);
        arrow.normals.as_mut().unwrap().extend(cone.normals.as_ref().unwrap());
        arrow
    }

    ///
    /// Computes the per vertex normals and updates the normals of the mesh.
    /// It will override the current normals if they already exist.
    ///
    pub fn compute_normals(&mut self) {
        if let Some(ref ind) = self.indices {
            self.normals = Some(compute_normals_with_indices(ind, &self.positions));
        } else {
            self.normals = Some(compute_normals(&self.positions));
        }
    }

    ///
    /// Computes the axis aligned bounding box of the mesh.
    ///
    pub fn compute_aabb(&self) -> AxisAlignedBoundingBox {
        AxisAlignedBoundingBox::new().expand(&self.positions)
    }
}

fn compute_normals_with_indices(indices: &[u32], positions: &[f32]) -> Vec<f32> {
    let mut normals = vec![0.0f32; positions.len() * 3];
    for face in 0..indices.len()/3 {
        let index0 = indices[face*3] as usize;
        let p0 = vec3(positions[index0*3], positions[index0*3+1], positions[index0*3+2]);
        let index1 = indices[face*3 + 1] as usize;
        let p1 = vec3(positions[index1*3], positions[index1*3+1], positions[index1*3+2]);
        let index2 = indices[face*3 + 2] as usize;
        let p2 = vec3(positions[index2*3], positions[index2*3+1], positions[index2*3+2]);

        let normal = (p1 - p0).cross(p2 - p0);
        normals[index0*3] += normal.x;
        normals[index0*3+1] += normal.y;
        normals[index0*3+2] += normal.z;
        normals[index1*3] += normal.x;
        normals[index1*3+1] += normal.y;
        normals[index1*3+2] += normal.z;
        normals[index2*3] += normal.x;
        normals[index2*3+1] += normal.y;
        normals[index2*3+2] += normal.z;
    }

    for i in 0..normals.len()/3 {
        let normal = vec3(normals[3*i], normals[3*i+1], normals[3*i+2]).normalize();
        normals[3*i] = normal.x;
        normals[3*i+1] = normal.y;
        normals[3*i+2] = normal.z;
    }
    normals
}


fn compute_normals(positions: &[f32]) -> Vec<f32> {
    let mut normals = vec![0.0f32; positions.len()];
    for face in 0..positions.len()/9 {
        let index0 = face*3 as usize;
        let p0 = vec3(positions[index0*3], positions[index0*3+1], positions[index0*3+2]);
        let index1 = face*3 + 1 as usize;
        let p1 = vec3(positions[index1*3], positions[index1*3+1], positions[index1*3+2]);
        let index2 = face*3 + 2 as usize;
        let p2 = vec3(positions[index2*3], positions[index2*3+1], positions[index2*3+2]);

        let normal = (p1 - p0).cross(p2 - p0);
        normals[index0*3] += normal.x;
        normals[index0*3+1] += normal.y;
        normals[index0*3+2] += normal.z;
        normals[index1*3] += normal.x;
        normals[index1*3+1] += normal.y;
        normals[index1*3+2] += normal.z;
        normals[index2*3] += normal.x;
        normals[index2*3+1] += normal.y;
        normals[index2*3+2] += normal.z;
    }

    for i in 0..normals.len()/3 {
        let normal = vec3(normals[3*i], normals[3*i+1], normals[3*i+2]).normalize();
        normals[3*i] = normal.x;
        normals[3*i+1] = normal.y;
        normals[3*i+2] = normal.z;
    }
    normals
}