Particle fields

examples/particles/particles.js

@@ -9,11 +9,11 @@ class BlueParticle extends MomentumEngine.Classes.Rect {
 
     constructor (x, y) {
         super(x, y, 1, 1, new MomentumEngine.Classes.Color(255, 255, 255, 0));
-        this.timeToLive = 5000;
+        this.timeToLive = 15000;
     }
 
     update (delta) {
-        this.color.a = this.color.a - (delta * 0.00025);
+        this.color.a = this.color.a - (delta * 0.00005);
     }
 
 }
@@ -37,17 +37,29 @@ window.onload = function () {
     });
 
     let black = new MomentumEngine.Classes.Color(0, 0, 0),
-        red = new MomentumEngine.Classes.Color(255, 0, 0);
+        red = new MomentumEngine.Classes.Color(255, 0, 0),
+        blue = new MomentumEngine.Classes.Color(0, 0, 255);
 
     let mainScene = new MomentumEngine.Classes.Rect(0, 0, width, height, black);
     particles.addChildEntity(mainScene);
 
-    let rect = new MomentumEngine.Classes.Rect(width / 2 - baseSize, height / 2 - baseSize, baseSize * 2, baseSize * 2, red),
+    let rect = new MomentumEngine.Classes.Rect(width / 8 - baseSize, height / 2 - baseSize, baseSize * 2, baseSize * 2, red),
         emitter = new MomentumEngine.Classes.Emitter(baseSize, baseSize, 4, new MomentumEngine.Classes.Vector2D(0, 0.05), BlueParticle);
 
+    let fieldRect = new MomentumEngine.Classes.Rect(width - (baseSize * 33), height - (baseSize * 10), baseSize * 2, baseSize * 2, blue),
+        field = new MomentumEngine.Classes.Field(baseSize, baseSize, 0.1);
+
+    let fieldRect2 = new MomentumEngine.Classes.Rect(width - (baseSize * 33), baseSize * 10, baseSize * 2, baseSize * 2, blue),
+        field2 = new MomentumEngine.Classes.Field(baseSize, baseSize, 0.1);
+
     mainScene.addChildEntity(rect);
     rect.addChildEntity(emitter);
 
+    mainScene.addChildEntity(fieldRect);
+    fieldRect.addChildEntity(field);
+    mainScene.addChildEntity(fieldRect2);
+    fieldRect2.addChildEntity(field2);
+
     rect.update = function (delta) {
 
         if (particles.inputs.keyboard.isPressed(KeyConsts.UP)) {
@@ -69,6 +81,8 @@ window.onload = function () {
     };
 
     emitter.setParticleParent(mainScene);
+    emitter.particleFields.push(field, field2);
+    //emitter.spread = Math.PI / 32;
     emitter.emitting = true;
 
     particles.start();

src/classes/emitter.js

@@ -3,6 +3,8 @@
 import Entity from "./entity.js";
 import Vector2D from "./vector2d.js";
 
+import Utils from "../libs/utils";
+
 
 class Emitter extends Entity {
 
@@ -13,6 +15,7 @@ class Emitter extends Entity {
 
         this.particleVelocity = velocity;
         this.particleClass = particle;
+        this.particleFields = [];
 
         this.rate = rate;
         this.emitting = false;
@@ -41,6 +44,7 @@ class Emitter extends Entity {
 
         let particle = new ParticleClass(this._calculatedPos.x, this._calculatedPos.y);
         particle.velocity = velocity;
+        Utils.mergeIntoArray(particle.fields, this.particleFields);
 
         //this._particles.push(particle);
         parent.addChildEntity(particle);

src/classes/entity.js

@@ -11,6 +11,8 @@ class Entity {
         this.velocity = new Vector2D(0, 0);
         this.acceleration = new Vector2D(0, 0);
 
+        this.fields = [];
+
         this.state = {};
         this.children = [];
 
@@ -130,6 +132,33 @@ class Entity {
     }
 
 
+    _calculateFields (delta) {
+
+        this._preprocess(); // NK: I don't like calling preprocess everywhere outside of the render method...
+
+        let acceleration = new Vector2D(0, 0);
+
+        for (let i = 0; i < this.fields.length; i++) {
+
+            let field = this.fields[i];
+            field._preprocess();
+
+            let vector = new Vector2D(
+                field._calculatedPos.x - this._calculatedPos.x,
+                field._calculatedPos.y - this._calculatedPos.y
+            );
+
+            let force = field.mass / Math.pow(vector.dot(vector), 1.5);
+
+            acceleration.add(vector.multiply(force).multiply(delta));
+
+        }
+
+        return this.acceleration.clone().add(acceleration);
+
+    }
+
+
     _updateEntity (delta) {
 
         if (this.timeToLive) {
@@ -139,12 +168,9 @@ class Entity {
         }
 
         // Calculate new position based on velocity and acceleration if there's one set
-        if (this.velocity) {
+        if (this.velocity && (this.velocity.x !== 0 || this.velocity.y !== 0)) {
-
-            if (this.acceleration) {
-                this.velocity.add(this.acceleration);
-            }
 
+            this.velocity.add(this._calculateFields(delta));
             this.pos.add(this.velocity.clone().multiply(delta));
 
         }

src/classes/field.js

@@ -0,0 +1,21 @@
+"use strict";
+
+import Entity from "./entity.js";
+import Vector2D from "./vector2d.js";
+
+
+class Field extends Entity {
+
+
+    constructor (x, y, mass) {
+
+        super(x, y);
+        this.mass = mass;
+
+    }
+
+
+}
+
+
+export default Field;

src/es5.js

@@ -2,6 +2,7 @@
 
 import Game from "./classes/game.js";
 import Emitter from "./classes/emitter.js";
+import Field from "./classes/field.js";
 import Entity from "./classes/entity.js";
 import Vector2D from "./classes/vector2d.js";
 import Sprite from "./classes/sprite.js";
@@ -13,14 +14,15 @@ import {KeyConsts} from "./classes/keyboardinput.js";
 
 
 const Classes = {
-    Game: Game,
+    Game,
-    Emitter: Emitter,
+    Emitter,
-    Entity: Entity,
+    Field,
-    Sprite: Sprite,
+    Entity,
-    Rect: Rect,
+    Sprite,
-    Vector2D: Vector2D,
+    Rect,
-    Color: Color,
+    Vector2D,
-    ImageLoader: ImageLoader
+    Color,
+    ImageLoader
 };
 
 

src/es6.js

@@ -2,6 +2,7 @@
 
 import Game from "./classes/game.js";
 import Emitter from "./classes/emitter.js";
+import Field from "./classes/field.js";
 import Entity from "./classes/entity.js";
 import Vector2D from "./classes/vector2d.js";
 import Sprite from "./classes/sprite.js";
@@ -13,14 +14,15 @@ import {KeyConsts} from "./classes/keyboardinput.js";
 
 
 const Classes = {
-    Game: Game,
+    Game,
-    Emitter: Emitter,
+    Emitter,
-    Entity: Entity,
+    Field,
-    Sprite: Sprite,
+    Entity,
-    Rect: Rect,
+    Sprite,
-    Vector2D: Vector2D,
+    Rect,
-    Color: Color,
+    Vector2D,
-    ImageLoader: ImageLoader
+    Color,
+    ImageLoader
 };
 
 

src/libs/utils.js

@@ -0,0 +1,20 @@
+class Utils {
+
+
+    static mergeIntoArray (dest, source) {
+
+        source.forEach((item) => {
+           if (dest.indexOf(item) < 0) {
+               dest.push(item);
+           }
+        });
+
+        return dest;
+
+    }
+
+
+}
+
+
+export default Utils;