rustbatch/math/
base.rs

1use crate::Vect;
2use std::mem;
3
4/// Base is useful for for simulating car movement though method is so precise that you can chain
5/// lot of bases and make totally smooth moving centipede
6#[derive(Copy, Clone, Debug)]
7pub struct  Base {
8    pub a: Vect,
9    pub b: Vect,
10    l: f32,
11}
12
13impl Base {
14    pub const ZERO: Self = Self { a: Vect::ZERO, b: Vect::ZERO, l: 0f32 };
15
16    #[inline]
17    pub fn new(a: Vect, b: Vect) -> Self {
18        Self{ a, b, l: (a - b).len() }
19    }
20
21    /// returns base rotation
22    #[inline]
23    pub fn rotation(&self) -> f32 {
24        (self.a - self.b).ang()
25    }
26
27    /// returns base center
28    #[inline]
29    pub fn center(&self) -> Vect {
30        self.a + (self.b - self.a)/2f32
31    }
32
33
34    fn mv(&mut self, delta: Vect) {
35        self.a += delta;
36        self.b += delta;
37    }
38
39    /// rotates base around pivot point
40    #[inline]
41    pub fn rotate_around(&mut self, delta: f32, point: Vect) {
42        self.mv(point.inverted());
43        self.a = self.a.rot(delta);
44        self.b = self.b.rot(delta);
45        self.mv(point);
46    }
47
48    /// rotates base around its center
49    #[inline]
50    pub fn rotate(&mut self, delta: f32) {
51        self.rotate_around(delta, self.center());
52    }
53
54    /// returns direction base is heading
55    #[inline]
56    pub fn dir(&self) -> Vect {
57        self.a - self.b
58    }
59
60    /// sets the base position
61    #[inline]
62    pub fn set_pos(&mut self, pos: Vect) {
63        let d = self.dir()/2f32;
64        self.a = pos + d;
65        self.b = pos - d;
66    }
67
68    /// sets the base rotation
69    #[inline]
70    pub fn set_rot(&mut self, rot: f32) {
71        let d = Vect::rad(rot ,self.l/2f32);
72        let c = self.center();
73        self.a = d + c;
74        self.b = d.inverted() + c;
75    }
76
77    /// tha main feature if base. Pulling base creates smooth movement where beck point is dragged by
78    /// front point. It returns the movement if back point witch you can use to move another base
79    /// "connected" to this one
80    #[inline]
81    pub fn pull(&mut self, mut force: Vect) -> Vect {
82        let mut l = force.len();
83
84        if l == 0.0 {
85            return Vect::ZERO
86        }
87
88        let mut extra = Vect::ZERO;
89
90        if l > self.l {
91            extra = force.norm() * self.l;
92            self.b = self.a + extra;
93            mem::swap(&mut self.a, &mut self.b);
94
95            force -= extra;
96            l -= self.l
97        }
98
99        let dir = self.dir();
100
101        let projected = Vect::rad(dir.ang_to(force), l);
102        let back_move = self.l - (self.l*self.l-projected.y*projected.y).sqrt() + projected.x;
103        let back_force = dir.norm() * back_move;
104
105        self.a += force;
106        self.b += back_force;
107
108        back_force + extra
109    }
110}
111
112#[cfg(test)]
113mod tests {
114    use crate::math::base::Base;
115    use crate::Vect;
116    #[test]
117    fn pull_test() {
118        let mut base = Base::new(vect!(0, 0), vect!(0, 100));
119        base.pull(vect!(1000, 0));
120        println!("{:?}", base);
121    }
122}
rustbatch/math/base.rs

rustbatch/math/
base.rs
