gh push for access

src/link.rs

@@ -0,0 +1,29 @@
+use crate::particle::Particle;
+use std::rc::Rc;
+use std::cell::RefCell;
+
+pub struct Link {
+    p1: Rc<RefCell<Particle>>,
+    p2: Rc<RefCell<Particle>>,
+    length: f32
+}
+
+impl Link {
+    pub fn new(p1: Rc<RefCell<Particle>>, p2: Rc<RefCell<Particle>>, length: f32) -> Self {
+        Link {
+            p1: p1,
+            p2: p2,
+            length: length
+        }
+    }
+
+    pub fn solve(&mut self) {
+        let vec = self.p2.borrow().pos - self.p1.borrow().pos;
+        let vec_len = (vec.x*vec.x + vec.y*vec.y).sqrt();
+        let vec_norm = vec/vec_len;
+        let vec_scaled = vec_norm * (self.length-vec_len) * 9.;
+
+        self.p1.borrow_mut().apply_force(-vec_scaled);
+        self.p2.borrow_mut().apply_force(vec_scaled);
+    }
+}