only substep solving; set only 3 attachment points

Cargo.lock

@@ -4,21 +4,21 @@ version = 4
 
 [[package]]
 name = "autocfg"
-version = "1.4.0"
+version = "1.5.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "ace50bade8e6234aa140d9a2f552bbee1db4d353f69b8217bc503490fc1a9f26"
+checksum = "c08606f8c3cbf4ce6ec8e28fb0014a2c086708fe954eaa885384a6165172e7e8"
 
 [[package]]
 name = "bitflags"
-version = "2.9.0"
+version = "2.9.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "5c8214115b7bf84099f1309324e63141d4c5d7cc26862f97a0a857dbefe165bd"
+checksum = "1b8e56985ec62d17e9c1001dc89c88ecd7dc08e47eba5ec7c29c7b5eeecde967"
 
 [[package]]
 name = "cc"
-version = "1.2.20"
+version = "1.2.31"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "04da6a0d40b948dfc4fa8f5bbf402b0fc1a64a28dbf7d12ffd683550f2c1b63a"
+checksum = "c3a42d84bb6b69d3a8b3eaacf0d88f179e1929695e1ad012b6cf64d9caaa5fd2"
 dependencies = [
  "shlex",
 ]
@@ -34,9 +34,9 @@ dependencies = [
 
 [[package]]
 name = "libc"
-version = "0.2.172"
+version = "0.2.174"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "d750af042f7ef4f724306de029d18836c26c1765a54a6a3f094cbd23a7267ffa"
+checksum = "1171693293099992e19cddea4e8b849964e9846f4acee11b3948bcc337be8776"
 
 [[package]]
 name = "libflac-sys"

src/link.rs

@@ -1,29 +1,31 @@
+use crate::math;
 use crate::particle::Particle;
-use std::rc::Rc;
 use std::cell::RefCell;
+use std::rc::Rc;
 
 pub struct Link {
     p1: Rc<RefCell<Particle>>,
     p2: Rc<RefCell<Particle>>,
-    length: f32
+    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
-        }
+        Link { p1, p2, 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.;
+        let vec_len = math::vec_len(vec);
 
-        self.p1.borrow_mut().apply_force(-vec_scaled);
-        self.p2.borrow_mut().apply_force(vec_scaled);
+        if vec_len > self.length {
+            let vec_norm = vec / vec_len;
+
+            let displacement = self.length - vec_len;
+            let vec_scaled = vec_norm * displacement / 2.;
+
+            self.p1.borrow_mut().apply_vel(-vec_scaled);
+            self.p2.borrow_mut().apply_vel(vec_scaled);
+        }
     }
-}
+}

src/main.rs

@@ -1,9 +1,11 @@
-use sfml::graphics::*;
-use sfml::window::*;
 use sfml::SfResult;
-use sfml::system::{Vector2f, Clock};
-use std::rc::Rc;
+use sfml::graphics::*;
+use sfml::system::{Clock, Vector2f};
+use sfml::window::*;
 use std::cell::RefCell;
+use std::rc::Rc;
+
+mod math;
 
 mod particle;
 use particle::Particle;
@@ -11,67 +13,148 @@ use particle::Particle;
 mod link;
 use link::Link;
 
-//const GRAVITY: f32 = 100.;
+const WIN_WIDTH: u32 = 800;
+const WIN_HEIGHT: u32 = 600;
 
-fn populate_particles(mut particles: Vec<Rc<RefCell<Particle>>>, num: u32) {
-    for i in 0..=num {
-        particles.push(Rc::new(RefCell::new(Particle::new(Vector2f::new(100. * i as f32, 300.)))));
+const GRAVITY: Vector2f = Vector2f::new(0., 1500.);
+
+const SUBSTEP_COUNT: u32 = 16;
+
+fn populate_particles(particles: &mut Vec<Rc<RefCell<Particle>>>, num: u32, cols: u32) {
+    for i in 0..num {
+        const OFFSET: u32 = 10;
+        let x_pos = (/* WIN_WIDTH/2 - cols/2*OFFSET */120 + OFFSET * (i % cols)) as f32;
+        let y_pos = (/* WIN_HEIGHT/2 - (num/cols)/2*OFFSET */40 + OFFSET * (i / cols)) as f32;
+        let immovable = i == 0 || i == cols - 1 || i == (cols / 2);
+        let particle = Particle::new((x_pos, y_pos), immovable);
+        particles.push(Rc::new(RefCell::new(particle)));
     }
 }
 
-fn populate_links(links: Vec<Link>, particles: Vec<Rc<RefCell<Particle>>>) {
-
+fn populate_circles(circles: &mut Vec<CircleShape>, num: u32, rad: f32, pts: usize) {
+    for _ in 0..num {
+        let mut circle = CircleShape::new(rad, pts);
+        circle.set_origin((rad, rad));
+        circles.push(circle);
+    }
 }
 
-fn apply_forces(particles: Vec<Rc<RefCell<Particle>>>) {
+fn populate_links(
+    links: &mut Vec<Link>,
+    particles: &[Rc<RefCell<Particle>>],
+    width: usize,
+    height: usize,
+) {
+    for y in 0..height {
+        for x in 0..width {
+            let i = y * width + x;
+
+            if x < width - 1 {
+                let right = i + 1;
+                let dist = math::vec_len(particles[i].borrow().pos - particles[right].borrow().pos);
+                let link = Link::new(Rc::clone(&particles[i]), Rc::clone(&particles[right]), dist);
+                links.push(link);
+            }
+
+            if y < height - 1 {
+                let below = i + width;
+                let dist = math::vec_len(particles[i].borrow().pos - particles[below].borrow().pos);
+                let link = Link::new(Rc::clone(&particles[i]), Rc::clone(&particles[below]), dist);
+                links.push(link);
+            }
+        }
+    }
+}
+
+/*fn populate_lines(lines: &mut Vec<RectangleShape>, circles: &Vec<CircleShape>, num: u32) {
+    for i in 0..num {
+        let rect = RectangleShape::with_size(Vector2f::new(100., 100.));
+    }
+}*/
+
+fn apply_forces(particles: &Vec<Rc<RefCell<Particle>>>) {
     for particle in particles {
+        let velocity = particle.borrow().vel;
         let mut borrowed = particle.borrow_mut();
-        // borrowed.apply_force(Vector2f::new(0., GRAVITY));
-        borrowed.apply_force(Vector2f::new(1., 1.));
-
+        borrowed.apply_force(GRAVITY);
+        borrowed.apply_force(-(velocity * 0.5));
     }
 }
 
-fn update_particles(particles: Vec<Rc<RefCell<Particle>>>, dt: f32) {
-    for particle in particles { particle.borrow_mut().update(dt); }
+fn update_particles(particles: &Vec<Rc<RefCell<Particle>>>, dt: f32) {
+    for particle in particles {
+        particle.borrow_mut().update(dt);
+    }
 }
 
-fn solve_links(links: Vec<Link>) {
-    for mut link in links { link.solve(); }
+fn solve_links(links: &mut Vec<Link>) {
+    for link in links {
+        link.solve();
+    }
 }
 
-fn update_positions(circles: Vec<CircleShape>) {
+fn update_particle_derivatives(particles: &Vec<Rc<RefCell<Particle>>>, dt: f32) {
+    for particle in particles {
+        particle.borrow_mut().update_derivatives(dt);
+    }
+}
 
+fn update_positions(circles: &mut Vec<CircleShape>, particles: &[Rc<RefCell<Particle>>]) {
+    for (index, circle) in circles.iter_mut().enumerate() {
+        circle.set_position(particles[index].borrow().pos);
+    }
+}
+
+fn draw_all(
+    window: &mut RenderWindow,
+    circles: &Vec<CircleShape>, /* lines: &Vec<RectangleShape> */
+) {
+    for circle in circles {
+        window.draw(circle);
+    }
+
+    // for line in lines {
+    //     window.draw(line);
+    // }
 }
 
 fn main() -> SfResult<()> {
     let mut window = RenderWindow::new(
-        (800, 600),
+        (WIN_WIDTH, WIN_HEIGHT),
         "Verlet",
         Style::CLOSE,
-        &Default::default()
+        &Default::default(),
     )?;
     window.set_framerate_limit(60);
 
     let mut clock = Clock::start()?;
 
+    let mouse_pos_prev = window.mouse_position();
+    let mut mouse_coords_prev = window.map_pixel_to_coords_current_view(mouse_pos_prev);
+
+    let particle_count: u32 = 2000;
+    let column_count: u32 = 50;
+    let row_count: u32 = particle_count / column_count;
+
     let mut particles: Vec<Rc<RefCell<Particle>>> = vec![];
-    populate_particles(particles, 3);
-    let particle1 = Rc::new(RefCell::new(Particle::new(Vector2f::new(200., 300.))));
-    let particle2 = Rc::new(RefCell::new(Particle::new(Vector2f::new(300., 300.))));
-    let particle3 = Rc::new(RefCell::new(Particle::new(Vector2f::new(400., 300.))));
+    populate_particles(&mut particles, particle_count, column_count);
 
-    let mut link1 = Link::new(Rc::clone(&particle1), Rc::clone(&particle2), 100.);
-    let mut link2 = Link::new(Rc::clone(&particle2), Rc::clone(&particle3), 100.);
-    let mut link3 = Link::new(Rc::clone(&particle1), Rc::clone(&particle3), 200.);
+    let mut links: Vec<Link> = vec![];
+    populate_links(
+        &mut links,
+        &particles,
+        column_count as usize,
+        row_count as usize,
+    );
+    // let mut link3 = Link::new(Rc::clone(&(particles[0])), Rc::clone(&(particles[2])), 200.);
 
-    let radius = 32.;
-    let mut circle1 = CircleShape::new(radius, 100);
-    let mut circle2 = CircleShape::new(radius, 100);
-    let mut circle3 = CircleShape::new(radius, 100);
-    circle1.set_origin((radius, radius));
-    circle2.set_origin((radius, radius));
-    circle3.set_origin((radius, radius));
+    let radius: f32 = 1.;
+    let point_count: usize = 100;
+    let mut circles: Vec<CircleShape> = vec![];
+    populate_circles(&mut circles, particle_count, radius, point_count);
+
+    // let mut lines: Vec<RectangleShape> = vec![];
+    // populate_lines(&mut lines, &circles, particle_count);
 
     while window.is_open() {
         while let Some(event) = window.poll_event() {
@@ -81,35 +164,39 @@ fn main() -> SfResult<()> {
             }
         }
 
+        let mouse_pos = window.mouse_position();
+        let mouse_coords = window.map_pixel_to_coords_current_view(mouse_pos);
+        let mouse_vel = mouse_coords - mouse_coords_prev;
+        mouse_coords_prev = mouse_coords;
+
         if mouse::Button::is_pressed(mouse::Button::Left) {
-            let mouse_pos = window.mouse_position();
-            let mouse_coords = window.map_pixel_to_coords_current_view(mouse_pos);
-            let p_pos = particle1.borrow().pos;
-            particle2.borrow_mut().apply_force(mouse_coords - p_pos);
+            for particle in &particles {
+                let p_pos = particle.borrow().pos;
+                let dist_vec = mouse_coords - p_pos;
+                let dist = math::vec_len(dist_vec);
+                if dist < 40. {
+                    particle.borrow_mut().apply_force(mouse_vel * 800.);
+                }
+            }
         }
 
         let dt = clock.restart().as_seconds();
+        let substep_dt = dt / SUBSTEP_COUNT as f32;
 
-        //particle.apply_force(Vector2f::new(0., GRAVITY));
-
-        particle1.borrow_mut().update(dt);
-        particle2.borrow_mut().update(dt);
-        particle3.borrow_mut().update(dt);
-
-        link1.solve();
-        link2.solve();
-        link3.solve();
-
-        circle1.set_position(particle1.borrow().pos);
-        circle2.set_position(particle2.borrow().pos);
-        circle3.set_position(particle3.borrow().pos);
+        //for _ in 0..SUBSTEP_COUNT {
+        apply_forces(&particles);
+        update_particles(&particles, dt);
+        for _ in 0..SUBSTEP_COUNT {
+            solve_links(&mut links);
+        }
+        update_particle_derivatives(&particles, dt);
+        update_positions(&mut circles, &particles);
+        //}
 
         window.clear(Color::BLACK);
-        window.draw(&circle1);
-        window.draw(&circle2);
-        window.draw(&circle3);
+        draw_all(&mut window, &circles /* &lines */);
         window.display();
     }
 
     Ok(())
-}
+}

src/math.rs

@@ -0,0 +1,5 @@
+use sfml::system::Vector2f;
+
+pub fn vec_len(vec: Vector2f) -> f32 {
+    (vec.x * vec.x + vec.y * vec.y).sqrt()
+}

src/particle.rs

@@ -3,28 +3,43 @@ use sfml::system::Vector2f;
 pub struct Particle {
     pub pos: Vector2f,
     prev_pos: Vector2f,
-    accel: Vector2f
+    pub vel: Vector2f,
+    accel: Vector2f,
+
+    immovable: bool,
 }
 
 impl Particle {
-    pub fn new(pos: Vector2f) -> Self {
+    pub fn new<P: Into<Vector2f>>(pos: P, immovable: bool) -> Self {
+        let pos = pos.into();
         Particle {
-            pos: pos,
+            pos,
             prev_pos: pos,
-            accel: Vector2f::default()
+            vel: Vector2f::default(),
+            accel: Vector2f::default(),
+
+            immovable,
         }
     }
 
-    pub fn apply_force(&mut self, force: Vector2f) {
-        self.accel += force;
+    pub fn apply_force<F: Into<Vector2f>>(&mut self, force: F) {
+        self.accel += force.into();
     }
 
     pub fn update(&mut self, dt: f32) {
-        let vel = (self.pos - self.prev_pos) * 0.99;
-        let new_pos = self.pos + vel + self.accel * (dt * dt);
-
+        if self.immovable {return}
         self.prev_pos = self.pos;
-        self.pos = new_pos;
+        self.vel += self.accel * dt;
+        self.pos += self.vel * dt;
+    }
+
+    pub fn update_derivatives(&mut self, dt: f32) {
+        self.vel = (self.pos - self.prev_pos) / dt;
         self.accel = Vector2f::default();
     }
-}
+
+    pub fn apply_vel(&mut self, vel: Vector2f) {
+        if self.immovable {return}
+        self.pos += vel;
+    }
+}