feat: allow watching particles

1 files changed, 43 insertions, 10 deletions

diff --git a/playground/src/main.rs b/playground/src/main.rs
index 1cb8198..f585efa 100644
--- a/playground/src/main.rs
+++ b/playground/src/main.rs
@@ -1,9 +1,9 @@
 use raylib::prelude::*;
 
+use physics::algebra::{Point, Scalar, Vector, N};
 use physics::force::{drag::Drag, gravity::Gravity, spring::Spring};
 use physics::nalgebra::Point as PointBase;
 use physics::particle_system::{Particle, ParticleSystem};
-use physics::algebra::{Point, Scalar, Vector, N};
 use physics::renderer::Camera;
 use physics::solver::Solver;
 
@@ -42,7 +42,7 @@ fn main() {
             Box::new(Spring {
                 particle_ids: [4, 2],
                 spring_constant: 0.75,
-                damping_constant: 0.1,
+                damping_constant: 0.3,
                 rest_length: 20.0,
             }),
         ],
@@ -58,6 +58,7 @@ fn main() {
     system.add_beam_constraint([5, 4]);
 
     let mut selected_particle_id = None;
+    let mut watch_particle_id = 0;
 
     let (mut rl, thread) = raylib::init()
         .size(640, 480)
@@ -83,7 +84,11 @@ fn main() {
             Color::BLACK,
         );
 
-        let camera = Camera::new(Point::origin(), Vector::y(), Vector::x());
+        let camera = Camera::new(
+            system.particles[watch_particle_id].position,
+            Vector::y(),
+            Vector::x(),
+        );
 
         match selected_particle_id {
             Some(particle_id) => {
@@ -139,12 +144,23 @@ fn main() {
                 }
             }
 
+            if d.is_mouse_button_pressed(MouseButton::MOUSE_BUTTON_RIGHT) {
+                let mouse_point =
+                    PointBase::<f32, 2>::new(d.get_mouse_x() as f32, d.get_mouse_y() as f32);
+                let position = PointBase::<f32, 2>::new(position.x as f32, position.y as f32);
+                if (position - mouse_point).norm() < radius {
+                    watch_particle_id = particle_id
+                }
+            }
+
             d.draw_circle(
                 position.x,
                 position.y,
                 radius,
                 if selected_particle_id.is_some_and(|v| v == particle_id) {
                     Color::RED
+                } else if watch_particle_id == particle_id {
+                    Color::YELLOW
                 } else {
                     Color::BLACK
                 },
@@ -153,8 +169,14 @@ fn main() {
         for c in &system.constraints {
             let particle_ids = c.get_particles();
             if particle_ids.len() == 2 {
-                let a = screen_space_to_raylib(system.particles[particle_ids[0]].position, &d);
-                let b = screen_space_to_raylib(system.particles[particle_ids[1]].position, &d);
+                let a = screen_space_to_raylib(
+                    camera.world_to_screen_space(system.particles[particle_ids[0]].position),
+                    &d,
+                );
+                let b = screen_space_to_raylib(
+                    camera.world_to_screen_space(system.particles[particle_ids[1]].position),
+                    &d,
+                );
 
                 d.draw_line(a.x, a.y, b.x, b.y, Color::GRAY);
             }
@@ -163,8 +185,14 @@ fn main() {
         {
             // Hard-coded spring
             let particle_ids = [4, 2];
-            let a = screen_space_to_raylib(system.particles[particle_ids[0]].position, &d);
-            let b = screen_space_to_raylib(system.particles[particle_ids[1]].position, &d);
+            let a = screen_space_to_raylib(
+                camera.world_to_screen_space(system.particles[particle_ids[0]].position),
+                &d,
+            );
+            let b = screen_space_to_raylib(
+                camera.world_to_screen_space(system.particles[particle_ids[1]].position),
+                &d,
+            );
             d.draw_line(a.x, a.y, b.x, b.y, Color::GREEN);
         }
         {
@@ -172,9 +200,14 @@ fn main() {
             match selected_particle_id {
                 Some(id) => {
                     let mouse_particle_id = system.particles.len() - 1;
-                    let a = screen_space_to_raylib(system.particles[id].position, &d);
-                    let b =
-                        screen_space_to_raylib(system.particles[mouse_particle_id].position, &d);
+                    let a = screen_space_to_raylib(
+                        camera.world_to_screen_space(system.particles[id].position),
+                        &d,
+                    );
+                    let b = screen_space_to_raylib(
+                        camera.world_to_screen_space(system.particles[mouse_particle_id].position),
+                        &d,
+                    );
 
                     d.draw_line(a.x, a.y, b.x, b.y, Color::GREEN);
                 }