refactor: velocity as polar

packages/physics/traits/emitted.trait.js

@@ -28,7 +28,10 @@ export class Emitted extends decorate(Trait) {
       },
       transient: true,
       ttl: 2,
-      velocity: [0, 0],
+      velocity: {
+        angle: 0,
+        magnitude: 0,
+      },
     };
   }
 
@@ -53,7 +56,8 @@ export class Emitted extends decorate(Trait) {
     this.scaleStart = new Range(this.params.scale.start);
     this.scaleEnd = new Range(this.params.scale.end);
     this.ttl = this.params.ttl;
-    this.velocity = new Vector.Range(this.params.velocity);
+    this.velocityAngle = new Range(this.params.velocity.angle);
+    this.velocityMagnitude = new Range(this.params.velocity.magnitude);
   }
 
   get isTransientParticle() {
@@ -65,7 +69,6 @@ export class Emitted extends decorate(Trait) {
 
       particle: () => {
         const position = null === this.position ? null : this.position.value();
-        const velocity = this.velocity.value();
         const force = this.force.value();
         return {
           alpha: {
@@ -85,7 +88,10 @@ export class Emitted extends decorate(Trait) {
             end: this.scaleEnd.value(),
           },
           ttl: this.ttl,
-          velocity,
+          velocity: {
+            angle: this.velocityAngle.value(),
+            magnitude: this.velocityMagnitude.value(),
+          },
         };
       },
 

packages/physics/traits/emitter.trait.js

@@ -46,13 +46,18 @@ export class Emitter extends decorate(Trait) {
       }
     }
     for (const key in this.params.particles) {
+      if (particles[key]) {
+        particles[key] = merge({}, particles[key], this.params.particles[key]);
+      }
+      else {
         particles[key] = this.params.particles[key];
       }
+    }
     this.particles = particles;
   }
 
   onParticleDead(particle) {
-    if (particle.isTransientParticle) {
+    if (particle.body.isTransientParticle) {
       particle.body.destroy();
     }
   }
@@ -107,8 +112,9 @@ export class Emitter extends decorate(Trait) {
           new Proton.Mass(particle.mass),
           new Proton.Life(particle.ttl),
           new Proton.Velocity(
-            particle.velocity[0],
-            particle.velocity[1]
+            particle.velocity.magnitude,
+            particle.velocity.angle,
+            'polar'
           ),
         ];
         const behaviors = [
@@ -160,7 +166,7 @@ export class Emitter extends decorate(Trait) {
         let {
           count = 1,
           rate = 0,
-        } = order;
+        } = mergedJson;
         if (0 === rate) {
           for (let i = 0; i < count; ++i) {
             this.entity.emitParticleJson(mergedJson);