Pheromone drops, test for utils

src/ant.ts

@@ -4,6 +4,8 @@ import { FoodItem } from "./food-item";
 import { World } from "./world";
 import { Colony } from "./colony";
 import { config } from "./config";
+import { IPheromoneType, Pheromone } from "./pheromone";
+import { distance } from "./utils";
 
 export enum IAntState {
   ReturningHome,
@@ -28,6 +30,8 @@ export class Ant {
       this.colony.position.x,
       this.colony.position.y
     );
+    // TODO: Move IPheromoneType to Pheromone
+    // this.world.depositPheromone(this.position.copy(), IPheromoneType.Wander);
     this.wanderAngle = 0;
     this.angle = p5i.random(p5i.TWO_PI);
     this.velocity = p5m.Vector.fromAngle(this.angle);
@@ -50,12 +54,15 @@ export class Ant {
   }
 
   private handleEdgeCollision() {
+    // left / right
     if (this.position.x > p5i.windowWidth - 10 || this.position.x < 10) {
       this.velocity.x *= -1;
     }
+    // top / bottom
     if (this.position.y > p5i.windowHeight - 10 || this.position.y < 10) {
       this.velocity.y *= -1;
     }
+    // TODO: ants should not be rendered over colonies
   }
 
   private handleWandering() {
@@ -96,7 +103,6 @@ export class Ant {
   }
 
   private handleReturningHome() {
-    // TODO: ants should not be rendered over colonies
     // check if food item is delivered to colony
     if (this.colony.collide(this.position)) {
       this.targetFoodItem.delivered();
@@ -109,6 +115,13 @@ export class Ant {
     this.applyForce(approachColony);
   }
 
+  private handlePheromoneDeposit() {
+    this.world.depositPheromone(
+      this.position.copy(),
+      this.isSearchingForFood() ? IPheromoneType.Wander : IPheromoneType.Food
+    );
+  }
+
   public searchingForFood() {
     this.state = IAntState.SearchingForFood;
   }
@@ -135,6 +148,7 @@ export class Ant {
   public update() {
     this.handleEdgeCollision();
     this.handleWandering();
+    this.handlePheromoneDeposit();
 
     this.isSearchingForFood() && this.handleSearchingForFood();
     this.isReturningHome() && this.handleReturningHome();

src/config.ts

@@ -22,7 +22,7 @@ export const config = {
   ant: {
     wanderStrength: 1,
     maxSpeed: 3,
-    steeringLimit: 0.4,
+    steeringLimit: 0.7,
     size: 2,
     color: "#000000",
     strokeWeight: 2,
@@ -34,4 +34,17 @@ export const config = {
       strokeWeight: 1,
     },
   },
+  pheromone: {
+    size: 3,
+    strokeWeight: 0,
+    distanceBetween: 10,
+    show: true,
+    evaporationRate: 0.007,
+    wander: {
+      color: "#1AA7EC",
+    },
+    food: {
+      color: "#D21F3C",
+    },
+  },
 };

src/pheromone.ts

@@ -0,0 +1,31 @@
+import { config } from "./config";
+import { p5i } from "./sketch";
+
+export enum IPheromoneType {
+  Wander,
+  Food,
+}
+
+export class Pheromone {
+  position: p5.Vector;
+  type: IPheromoneType;
+  strength: number;
+
+  constructor(position: p5.Vector, type: IPheromoneType) {
+    this.position = position;
+    this.type = type;
+    this.strength = 1;
+  }
+
+  public evaporate() {
+    this.strength -= config.pheromone.evaporationRate;
+  }
+
+  public render() {
+    p5i.push();
+    p5i.strokeWeight(config.pheromone.strokeWeight);
+    p5i.fill(255, 0, 0, this.strength * 100);
+    p5i.circle(this.position.x, this.position.y, config.pheromone.size);
+    p5i.pop();
+  }
+}

src/sketch.ts

@@ -3,7 +3,7 @@ import { World } from "./world";
 import { config } from "./config";
 
 let world: World;
-const numAnts: number = 700;
+const numAnts: number = 10;
 
 const sketch = (p: p5) => {
   p.setup = () => {

src/utils.ts

@@ -1,11 +1,12 @@
+export const distance = (position1: p5.Vector, position2: p5.Vector): number =>
+  // Euclidean distance equivalent to p5.dist(x1, y1, x2, y2)
+  Math.sqrt(
+    Math.pow(position1.x - position2.x, 2) +
+      Math.pow(position1.y - position2.y, 2)
+  );
+
 export const circleCollision = (
   candidatePosition: p5.Vector,
   circlePosition: p5.Vector,
-  circleDiameter: number // diameter
-): boolean =>
-  // Euclidean distance equivalent to p5.dist(x1, y1, x2, y2)
-  Math.sqrt(
-    Math.pow(candidatePosition.x - circlePosition.x, 2) +
-      Math.pow(candidatePosition.y - circlePosition.y, 2)
-  ) <=
-  circleDiameter / 2;
+  circleDiameter: number
+): boolean => distance(candidatePosition, circlePosition) <= circleDiameter / 2;

src/world.ts

@@ -4,16 +4,20 @@ import { Ant } from "./ant";
 import { FoodItem } from "./food-item";
 import { Colony } from "./colony";
 import { config } from "./config";
+import { IPheromoneType, Pheromone } from "./pheromone";
+import { distance } from "./utils";
 
 export class World {
   ants: Ant[];
   foodItems: FoodItem[];
   colonies: Colony[];
+  pheromones: Pheromone[];
 
   constructor() {
     this.ants = [];
     this.foodItems = [];
     this.colonies = [new Colony()];
+    this.pheromones = [];
   }
 
   public createAnt() {
@@ -34,6 +38,21 @@ export class World {
     }
   }
 
+  private shouldPheromoneBeDeposited(position: p5.Vector) {
+    if (this.pheromones.length === 0) {
+      return true;
+    }
+    return (
+      distance(position, this.pheromones.at(-1).position) >
+      config.pheromone.distanceBetween
+    );
+  }
+
+  public depositPheromone(position: p5.Vector, type: IPheromoneType) {
+    this.shouldPheromoneBeDeposited(position) &&
+      this.pheromones.push(new Pheromone(position, type));
+  }
+
   // TODO: this method should limit the perception to only in FRONT of the ant
   public getFoodItemInPerceptionRange(
     antPosition: p5m.Vector,
@@ -55,6 +74,17 @@ export class World {
     }
   }
 
+  private renderPheromones() {
+    for (let i = 0; i < this.pheromones.length; i++) {
+      const pheromone = this.pheromones[i];
+      pheromone.evaporate();
+      if (pheromone.strength <= 0) {
+        this.pheromones.splice(i, 1);
+      }
+      pheromone.render();
+    }
+  }
+
   public render() {
     p5i.background(config.world.background);
     this.colonies.map((colony) => {
@@ -67,5 +97,6 @@ export class World {
     this.foodItems.map((food) => {
       food.render();
     });
+    config.pheromone.show && this.renderPheromones();
   }
 }

tests/utils.test.ts

@@ -1,9 +1,23 @@
 import * as p5m from "p5";
-import { circleCollision } from "../src/utils";
+import { distance, circleCollision } from "../src/utils";
 
 let circlePosition: p5m.Vector;
 let circleDiameter: number;
 
+describe("distance", () => {
+  test.only("should return the Euclidean distance between 2 points in a 2D space", () => {
+    expect(distance(new p5m.Vector(2, 3), new p5m.Vector(2, 7))).toBe(4);
+  });
+  test.only("should return 0 if both points are the same", () => {
+    expect(distance(new p5m.Vector(2, 3), new p5m.Vector(2, 3))).toBe(0);
+  });
+  test.only("should return the Euclidean distance between 2 points in a 2D space float", () => {
+    expect(distance(new p5m.Vector(3, 5), new p5m.Vector(-2, 4))).toBeCloseTo(
+      5.099
+    );
+  });
+});
+
 describe("circleCollision", () => {
   beforeEach(() => {
     circlePosition = new p5m.Vector(10, 10);