Merge pull request #18 from Ewpratten/boids

Boids

src/entities/fish.rs

@@ -8,10 +8,20 @@ const FISH_FOLLOW_PLAYER_SPEED: f32 = 1.8;
 const FISH_FOLLOW_PLAYER_SPEED_FAST: f32 = FISH_FOLLOW_PLAYER_SPEED * 3.0;
 const FISH_ATTACH_RADIUS: f32 = 20.0;
 
+const FISH_VISION: f32 = 25.0;
+const FISH_MAX_SPEED: f32 = 2.0;
+const FISH_MAX_FORCE: f32 = 0.05;
+const FISH_FACTOR_ATTRACTION: f32 = 1.0;
+const FISH_FACTOR_PLAYER: f32 = 0.1;
+const FISH_FACTOR_COHESION: f32 = 0.1;
+const FISH_SEPARATION_DISTANCE: f32 = 15.0;
+const FISH_FACTOR_SEPARATION: f32 = 1.5;
+
 #[derive(Debug, Clone)]
 pub struct FishEntity {
     position: Vector2,
     direction: Vector2,
+    velocity: Vector2,
     pub following_player: bool,
     size: Vector2,
     rng: ThreadRng
@@ -22,6 +32,7 @@ impl FishEntity {
         Self {
             position: position,
             direction: Vector2::zero(),
+            velocity: Vector2::zero(),
             following_player: false,
             size: Vector2 { x: 5.0, y: 8.0 },
             rng: rand::thread_rng()
@@ -37,33 +48,80 @@ impl FishEntity {
     }
 
     pub fn handle_follow_player(&mut self, player: &Player, dt: f64, other_fish: &Vec<FishEntity>) {
-        // Distance and direction to player
-        let dist_to_player = player.position - self.position;
-        let dist_to_player_lin = self.position.distance_to(player.position);
-        let mut direction_to_player = dist_to_player;
-        direction_to_player.normalize();
+        let mut acceleration: Vector2 = Vector2::zero();
  
-        // Fish movement
-        let movement;
-
-        // Random variance
-        let variance = self.rng.gen_range(500.0..1000.0) / 1000.0;
-
-        // If the fish is double its follow distance from the player
-        if dist_to_player_lin.abs() > (FISH_FOLLOW_PLAYER_DISTANCE * 2.0) {
-            movement = direction_to_player * FISH_FOLLOW_PLAYER_SPEED_FAST * variance;
-        } else {
-            // Move slowly in the direction of the player unless too close
-            if dist_to_player_lin.abs() > FISH_FOLLOW_PLAYER_DISTANCE {
-                movement = direction_to_player * FISH_FOLLOW_PLAYER_SPEED * variance;
-            } else {
-                movement = Vector2::zero();
+        let mut steer: Vector2 = Vector2::zero();
+        let mut count1: u16 = 0;
+        let mut sum1: Vector2 = Vector2::zero();
+        let mut count2: u16 = 0;
+        let mut sum2: Vector2 = Vector2::zero();
+        let mut count3: u16 = 0;
+        // separation
+        for i in other_fish {
+            let dist = (self.position - i.position).length();
+            if dist < FISH_SEPARATION_DISTANCE && dist > 0.0 {
+                let mut diff: Vector2 = self.position - i.position;
+                diff.normalize();
+                diff /= dist;
+                steer += diff;
+                count1 += 1;
+            }
+            if dist < FISH_VISION && dist > 0.0 {
+                sum1 += i.direction;
+                count2 += 1;
+                sum2 += i.position;
+                count3 += 1;
             }
         }
+        if count1 > 0 {
+            steer /= count1 as f32;
+        }
+        if steer.x != 0.0 || steer.y != 0.0 {
+            steer.normalize();
+            steer *= FISH_MAX_SPEED;
+            steer -= self.velocity;
+            steer.x = f32::min(f32::max(steer.x, -FISH_MAX_FORCE), FISH_MAX_FORCE);
+            steer.y = f32::min(f32::max(steer.y, -FISH_MAX_FORCE), FISH_MAX_FORCE);
+            acceleration += steer * FISH_FACTOR_SEPARATION;
+        }
+
+        // attraction
+        if count2 > 0 {
+            sum1 /= count2 as f32;
+            sum1.normalize();
+            sum1 *= FISH_MAX_SPEED;
+            sum1 -= self.velocity;
+            sum1.x = f32::min(f32::max(sum1.x, -FISH_MAX_FORCE), FISH_MAX_FORCE);
+            sum1.y = f32::min(f32::max(sum1.y, -FISH_MAX_FORCE), FISH_MAX_FORCE);
+            acceleration += sum1 * FISH_FACTOR_ATTRACTION;
+        }
+
+        // cohesion
+        if count3 > 0 {
+            sum2 /= count3 as f32;
+            let mut desired: Vector2 = sum2 - self.position;
+
+            desired.normalize();
+            desired *= FISH_MAX_SPEED;
+
+            desired.x = f32::min(f32::max(desired.x, -FISH_MAX_FORCE), FISH_MAX_FORCE);
+            desired.y = f32::min(f32::max(desired.y, -FISH_MAX_FORCE), FISH_MAX_FORCE);
+
+            acceleration += desired * FISH_FACTOR_COHESION;
+        }
+
+        // turn to player
+        let mut player_factor: Vector2 = player.position - self.position;
+        player_factor.normalize();
+        acceleration += player_factor * FISH_FACTOR_PLAYER;
 
         // Move the fish
-        self.direction = direction_to_player;
-        self.position += movement;
+        self.direction = self.velocity.normalized();
+        self.velocity += acceleration;
+        
+        self.velocity.x = f32::min(f32::max(self.velocity.x, -FISH_MAX_SPEED), FISH_MAX_SPEED);
+        self.velocity.y = f32::min(f32::max(self.velocity.y, -FISH_MAX_SPEED), FISH_MAX_SPEED);
+        self.position += self.velocity;
     }
 
     pub fn handle_free_movement(&mut self, player: &mut Player, dt: f64) {
@@ -76,6 +134,7 @@ impl FishEntity {
         // Handle player picking up fish
         if player.position.distance_to(self.position).abs() <= player.size.y * 2.2 {
             self.following_player = true;
+            self.velocity = self.direction.normalized();
 
             // Add currency to the player
             player.coins += 1;