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comparison utils/src/math.rs @ 757:21b186be2590

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Split the Rust version into multiple crates.
author Emmanuel Gil Peyrot <linkmauve@linkmauve.fr>
date Tue, 05 Jan 2021 02:16:32 +0100
parents src/util/math.rs@01849ffd0180
children
comparison
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756:4d91790cf8ab 757:21b186be2590
1 //! Various helpers to deal with vectors and matrices.
2
3 /// A 4×4 f32 matrix type.
4 pub struct Mat4 {
5 inner: [[f32; 4]; 4]
6 }
7
8 impl Mat4 {
9 /// Create a new matrix from a set of 16 f32.
10 pub fn new(inner: [[f32; 4]; 4]) -> Mat4 {
11 Mat4 {
12 inner
13 }
14 }
15
16 fn zero() -> Mat4 {
17 Mat4 {
18 inner: [[0.; 4]; 4]
19 }
20 }
21
22 fn identity() -> Mat4 {
23 Mat4 {
24 inner: [[1., 0., 0., 0.],
25 [0., 1., 0., 0.],
26 [0., 0., 1., 0.],
27 [0., 0., 0., 1.]]
28 }
29 }
30
31 /// Immutably borrow the array of f32 inside this matrix.
32 pub fn borrow_inner(&self) -> &[[f32; 4]; 4] {
33 &self.inner
34 }
35
36 /// Scale the matrix in 2D.
37 pub fn scale2d(&mut self, x: f32, y: f32) {
38 for i in 0..4 {
39 self.inner[0][i] *= x;
40 self.inner[1][i] *= y;
41 }
42 }
43
44 /// Flip the matrix.
45 pub fn flip(&mut self) {
46 for i in 0..4 {
47 self.inner[0][i] = -self.inner[0][i];
48 }
49 }
50
51 /// Rotate the matrix around its x angle (in radians).
52 pub fn rotate_x(&mut self, angle: f32) {
53 let mut lines: [f32; 8] = [0.; 8];
54 let cos_a = angle.cos();
55 let sin_a = angle.sin();
56 for i in 0..4 {
57 lines[ i] = self.inner[0][i];
58 lines[4 + i] = self.inner[1][i];
59 }
60 for i in 0..4 {
61 self.inner[1][i] = cos_a * lines[i] - sin_a * lines[4+i];
62 self.inner[2][i] = sin_a * lines[i] + cos_a * lines[4+i];
63 }
64 }
65
66 /// Rotate the matrix around its y angle (in radians).
67 pub fn rotate_y(&mut self, angle: f32) {
68 let mut lines: [f32; 8] = [0.; 8];
69 let cos_a = angle.cos();
70 let sin_a = angle.sin();
71 for i in 0..4 {
72 lines[ i] = self.inner[0][i];
73 lines[4 + i] = self.inner[2][i];
74 }
75 for i in 0..4 {
76 self.inner[0][i] = cos_a * lines[i] + sin_a * lines[4+i];
77 self.inner[2][i] = -sin_a * lines[i] + cos_a * lines[4+i];
78 }
79 }
80
81 /// Rotate the matrix around its z angle (in radians).
82 pub fn rotate_z(&mut self, angle: f32) {
83 let mut lines: [f32; 8] = [0.; 8];
84 let cos_a = angle.cos();
85 let sin_a = angle.sin();
86 for i in 0..4 {
87 lines[ i] = self.inner[0][i];
88 lines[4 + i] = self.inner[1][i];
89 }
90 for i in 0..4 {
91 self.inner[0][i] = cos_a * lines[i] - sin_a * lines[4+i];
92 self.inner[1][i] = sin_a * lines[i] + cos_a * lines[4+i];
93 }
94 }
95
96 /// Translate the matrix by a 3D offset.
97 pub fn translate(&mut self, offset: [f32; 3]) {
98 let mut item: [f32; 3] = [0.; 3];
99 for i in 0..3 {
100 item[i] = self.inner[3][i] * offset[i];
101 }
102 for i in 0..3 {
103 for j in 0..4 {
104 self.inner[i][j] += item[i];
105 }
106 }
107 }
108
109 /// Translate the matrix by a 2D offset.
110 pub fn translate_2d(&mut self, x: f32, y: f32) {
111 let offset = [x, y, 0.];
112 self.translate(offset);
113 }
114 }
115
116 impl std::ops::Mul<Mat4> for Mat4 {
117 type Output = Mat4;
118 fn mul(self, rhs: Mat4) -> Mat4 {
119 let mut tmp = Mat4::zero();
120 for i in 0..4 {
121 for j in 0..4 {
122 for k in 0..4 {
123 tmp.inner[i][j] += self.inner[i][k] * rhs.inner[k][j];
124 }
125 }
126 }
127 tmp
128 }
129 }
130
131 /// Create an orthographic projection matrix.
132 pub fn ortho_2d(left: f32, right: f32, bottom: f32, top: f32) -> Mat4 {
133 let mut mat = Mat4::identity();
134 mat.inner[0][0] = 2. / (right - left);
135 mat.inner[1][1] = 2. / (top - bottom);
136 mat.inner[2][2] = -1.;
137 mat.inner[3][0] = -(right + left) / (right - left);
138 mat.inner[3][1] = -(top + bottom) / (top - bottom);
139 mat
140 }
141
142 /// Setup a camera view matrix.
143 pub fn setup_camera(dx: f32, dy: f32, dz: f32) -> Mat4 {
144 // Some explanations on the magic constants:
145 // 192. = 384. / 2. = width / 2.
146 // 224. = 448. / 2. = height / 2.
147 // 835.979370 = 224./math.tan(math.radians(15)) = (height/2.)/math.tan(math.radians(fov/2))
148 // This is so that objects on the (O, x, y) plane use pixel coordinates
149 look_at([192., 224., -835.979370 * dz], [192. + dx, 224. - dy, 0.], [0., -1., 0.])
150 }
151
152 /// Creates a perspective projection matrix.
153 pub fn perspective(fov_y: f32, aspect: f32, z_near: f32, z_far: f32) -> Mat4 {
154 let top = (fov_y / 2.).tan() * z_near;
155 let bottom = -top;
156 let left = -top * aspect;
157 let right = top * aspect;
158
159 let mut mat = Mat4::identity();
160 mat.inner[0][0] = (2. * z_near) / (right - left);
161 mat.inner[1][1] = (2. * z_near) / (top - bottom);
162 mat.inner[2][2] = -(z_far + z_near) / (z_far - z_near);
163 mat.inner[2][3] = -1.;
164 mat.inner[3][2] = -(2. * z_far * z_near) / (z_far - z_near);
165 mat.inner[3][3] = 0.;
166 mat
167 }
168
169 type Vec3 = [f32; 3];
170
171 fn look_at(eye: Vec3, center: Vec3, up: Vec3) -> Mat4 {
172 let f = normalize(sub(center, eye));
173 let u = normalize(up);
174 let s = normalize(cross(f, u));
175 let u = cross(s, f);
176
177 Mat4::new([[s[0], u[0], -f[0], 0.],
178 [s[1], u[1], -f[1], 0.],
179 [s[2], u[2], -f[2], 0.],
180 [-dot(s, eye), -dot(u, eye), dot(f, eye), 1.]])
181 }
182
183 fn sub(a: Vec3, b: Vec3) -> Vec3 {
184 [a[0] - b[0],
185 a[1] - b[1],
186 a[2] - b[2]]
187 }
188
189 fn normalize(vec: Vec3) -> Vec3 {
190 let normal = 1. / (vec[0] * vec[0] + vec[1] * vec[1] + vec[2] * vec[2]).sqrt();
191 [vec[0] * normal, vec[1] * normal, vec[2] * normal]
192 }
193
194 fn cross(a: Vec3, b: Vec3) -> Vec3 {
195 [a[1] * b[2] - b[1] * a[2],
196 a[2] * b[0] - b[2] * a[0],
197 a[0] * b[1] - b[0] * a[1]]
198 }
199
200 fn dot(a: Vec3, b: Vec3) -> f32 {
201 a[0] * b[0] + a[1] * b[1] + a[2] * b[2]
202 }