From c148bc2456c08abe65c50d4b8b8525085a1485ea Mon Sep 17 00:00:00 2001
From: cha0s <git@cha0s.io>
Date: Sat, 4 May 2019 13:31:16 -0500
Subject: [PATCH] fix: physics apply stepTime as impulse

---
 packages/entity/traits/mobile.trait.js    | 2 +-
 packages/physics/abstract/body.js         | 3 ++-
 packages/physics/abstract/world.js        | 1 +
 packages/physics/dummy/body.js            | 8 ++++----
 packages/physics/dummy/world.js           | 2 +-
 packages/physics/matter/body.js           | 8 ++++----
 packages/physics/matter/world.js          | 2 +-
 packages/physics/traits/physical.trait.js | 4 ++--
 8 files changed, 16 insertions(+), 14 deletions(-)

diff --git a/packages/entity/traits/mobile.trait.js b/packages/entity/traits/mobile.trait.js
index 568a568..d4e34a3 100644
--- a/packages/entity/traits/mobile.trait.js
+++ b/packages/entity/traits/mobile.trait.js
@@ -62,7 +62,7 @@ class MobileBase extends Trait {
       return;
     }
     if (this.entity.is('physical')) {
-      this.entity.applyImpulse(this.requestedMovement, elapsed);
+      this.entity.applyImpulse(this.requestedMovement);
     }
     else {
       const requestedMovement = Vector.scale(
diff --git a/packages/physics/abstract/body.js b/packages/physics/abstract/body.js
index 47ee177..9460b80 100644
--- a/packages/physics/abstract/body.js
+++ b/packages/physics/abstract/body.js
@@ -10,9 +10,10 @@ const decorate = compose(
 
 export class AbstractBody extends decorate(class {}) {
 
-  constructor(shape) {
+  constructor(world, shape) {
     super();
     this.shape = shape;
+    this.world = world;
   }
 
 }
diff --git a/packages/physics/abstract/world.js b/packages/physics/abstract/world.js
index ff32211..43fef62 100644
--- a/packages/physics/abstract/world.js
+++ b/packages/physics/abstract/world.js
@@ -34,6 +34,7 @@ export class AbstractWorld extends decorate(class {}) {
         this.entitiesList.splice(index, 1);
       }
     }
+    body.world = null;
   }
 
   tick(elapsed) {
diff --git a/packages/physics/dummy/body.js b/packages/physics/dummy/body.js
index 3e1ef53..ce895c6 100644
--- a/packages/physics/dummy/body.js
+++ b/packages/physics/dummy/body.js
@@ -15,8 +15,8 @@ const decorate = compose(
 
 export class Body extends decorate(AbstractBody) {
 
-  constructor(shape) {
-    super(shape);
+  constructor(world, shape) {
+    super(world, shape);
     this.force = [0, 0];
     this.impulse = [0, 0];
     this.contacts = I.Set();
@@ -30,10 +30,10 @@ export class Body extends decorate(AbstractBody) {
     this.force = Vector.add(this.force, vector);
   }
 
-  applyImpulse(vector, elapsed) {
+  applyImpulse(vector) {
     this.impulse = Vector.add(
       this.impulse,
-      Vector.scale(vector, elapsed)
+      Vector.scale(vector, this.world.stepTime)
     );
   }
 
diff --git a/packages/physics/dummy/world.js b/packages/physics/dummy/world.js
index 026c418..9091d69 100644
--- a/packages/physics/dummy/world.js
+++ b/packages/physics/dummy/world.js
@@ -37,7 +37,7 @@ export class World extends AbstractWorld {
   }
 
   createBody(shape) {
-    return new Body(shape);
+    return new Body(this, shape);
   }
 
   removeBody(body) {
diff --git a/packages/physics/matter/body.js b/packages/physics/matter/body.js
index c541d67..3186729 100644
--- a/packages/physics/matter/body.js
+++ b/packages/physics/matter/body.js
@@ -47,8 +47,8 @@ export class Body extends AbstractBody {
     this.bodies.set(matterBody, avocadoBody);
   }
 
-  constructor(shape) {
-    super(shape);
+  constructor(world, shape) {
+    super(world, shape);
     const [body, position, origin] = this.constructor.bodyFromShape(shape);
     // Set body first, then origin, then position. Order important.
     this.matterBody = body;
@@ -73,9 +73,9 @@ export class Body extends AbstractBody {
     MatterBody.applyForce(this.matterBody, this.matterBody.position, {x, y});
   }
 
-  applyImpulse(impulse, elapsed) {
+  applyImpulse(impulse) {
     impulse = Vector.scale(impulse, 1 / SCALE);
-    impulse = Vector.scale(impulse, elapsed);
+    impulse = Vector.scale(impulse, this.world.stepTime);
     const [x, y] = impulse;
     MatterBody.translate(this.matterBody, {x, y});
   }
diff --git a/packages/physics/matter/world.js b/packages/physics/matter/world.js
index 8ca1779..048178e 100644
--- a/packages/physics/matter/world.js
+++ b/packages/physics/matter/world.js
@@ -27,7 +27,7 @@ export class World extends AbstractWorld {
   }
 
   createBody(shape) {
-    return new Body(shape);
+    return new Body(this, shape);
   }
 
   handleCollisions(eventName) {
diff --git a/packages/physics/traits/physical.trait.js b/packages/physics/traits/physical.trait.js
index 97baed7..1a234ec 100644
--- a/packages/physics/traits/physical.trait.js
+++ b/packages/physics/traits/physical.trait.js
@@ -115,9 +115,9 @@ export class Physical extends decorate(Trait) {
         }
       },
 
-      applyImpulse: (impulse, elapsed) => {
+      applyImpulse: (impulse) => {
         if (this._world && this._body) {
-          this._body.applyImpulse(impulse, elapsed);
+          this._body.applyImpulse(impulse);
         }
       },