Added coherence law

src/main.rs

@@ -1,3 +1,11 @@
+/// file: main.rs
+/// author: Rohmer Maxime <maxluligames@gmail.com>
+/// date: 10/05/2022
+/// version: 0.1.0
+/// Sources: 
+/// https://eater.net/boids
+/// https://docs.rs/sdl2/latest/sdl2/
+
 use sdl2::pixels::Color;
 use sdl2::event::Event;
 use sdl2::keyboard::Keycode;
@@ -13,8 +21,11 @@ const WINDOW_WIDTH:i32 = 800;
 const BIRD_SPEED:i32 = 2;
 const MAX_BIRD_SPEED:i32 = 10;
 const BIRDS_COUNT:i32 = 50;
-const MIN_BIRD_SIZE:i32 = 20;
+const BIRD_SIZE:i32 = 15;
-const MAX_BIRD_SIZE:i32 = 30;
+
+const COHERENCE_RATE:i32 = 1;
+const SEPRATION_RATE:i32 = 5;
+const ALIGNEMENT_RATE:i32 = 5;
 
 pub struct Bird{
     shape:Rect,
@@ -32,8 +43,68 @@ impl Simulation{
         for bird in self.birds.iter(){
             ctx.fill_rect(bird.shape).expect("Rusty Boids");
         }
+    }
+    pub fn apply_coherence(&mut self){
+        
+        // first we calculate all the averages for every birds
+        let mut averages:Vec<Point> = Vec::with_capacity(BIRDS_COUNT as usize);
+        for i in 0..BIRDS_COUNT{
+            let mut sum = Point::new(0,0);
+            for bird in &self.birds{
+                sum.x += bird.shape.x;
+                sum.y += bird.shape.y;
+            }
+            let average = Point::new(sum.x / BIRDS_COUNT as i32,sum.y / BIRDS_COUNT as i32);
+            averages.push(average);
+        }
+        
+        for i in 0..BIRDS_COUNT{
+            //now we need to steer torwards it 
+            let bird =  &mut self.birds[i as usize];
+            let posx = bird.shape.x;
+            let posy = bird.shape.y;
+            let average = averages[i as usize];
+
+            if posx > average.x{
+                if bird.velocity.x - COHERENCE_RATE < -MAX_BIRD_SPEED{
+                    bird.velocity.x = -MAX_BIRD_SPEED;
+                }else{
+                    bird.velocity.x -= COHERENCE_RATE;
+                }
+            }else{
+                if bird.velocity.x + COHERENCE_RATE > MAX_BIRD_SPEED{
+                    bird.velocity.x = MAX_BIRD_SPEED;
+                }else{
+                    bird.velocity.x += COHERENCE_RATE;
+                }
+            }
+
+            if posy > average.y{
+                if bird.velocity.y - COHERENCE_RATE < -MAX_BIRD_SPEED{
+                    bird.velocity.y = -MAX_BIRD_SPEED;
+                }else{
+                    bird.velocity.y -= COHERENCE_RATE;
+                }
+            }else{
+                if bird.velocity.y + COHERENCE_RATE > MAX_BIRD_SPEED{
+                    bird.velocity.y = MAX_BIRD_SPEED;
+                }else{
+                    bird.velocity.y += COHERENCE_RATE;
+                }
+            }
+        }
+        
+    }
+    pub fn apply_separation(&mut self){
+
+    }
+    pub fn apply_alignement(&mut self){
+
     }
     pub fn update(&mut self){
+        self.apply_coherence();
+        self.apply_separation();
+        self.apply_alignement();
         for bird in &mut self.birds{
             let mut posx = bird.shape.x;
             let mut posy = bird.shape.y;
@@ -97,8 +168,7 @@ pub fn generate_birds() -> Vec<Bird>{
     let mut rng = rand::thread_rng();
     let mut birds = Vec::with_capacity(BIRDS_COUNT as usize);
     for bird in  0..BIRDS_COUNT{
-        let size = rng.gen_range(MIN_BIRD_SIZE as u32..MAX_BIRD_SIZE as u32);
+        let rectangle = Rect::new(rng.gen_range(0..WINDOW_WIDTH - BIRD_SIZE),rng.gen_range(0..WINDOW_HEIGHT - BIRD_SIZE),BIRD_SIZE as u32, BIRD_SIZE as u32);
-        let rectangle = Rect::new(rng.gen_range(0..WINDOW_WIDTH - MAX_BIRD_SIZE),rng.gen_range(0..WINDOW_HEIGHT - MAX_BIRD_SIZE),size, size);
         let velocity = Point::new(rng.gen_range(0..MAX_BIRD_SPEED), rng.gen_range(0..MAX_BIRD_SPEED));
         birds.push(Bird{shape:rectangle,velocity:velocity});
     }
@@ -108,7 +178,7 @@ pub fn main() {
     let sdl_context = sdl2::init().unwrap();
     let video_subsystem = sdl_context.video().unwrap();
 
-    let window = video_subsystem.window("Test SDL Rust", WINDOW_WIDTH as u32, WINDOW_HEIGHT as u32)
+    let window = video_subsystem.window("Rust Boids Simulation", WINDOW_WIDTH as u32, WINDOW_HEIGHT as u32)
         .position_centered()
         .build()
         .unwrap();