fix fixture proxies reactivation

src/dynamics/Body.ts

@@ -435,7 +435,7 @@ export class Body {
  // Touch the proxies so that new contacts will be created (when appropriate)
  const broadPhase = this.m_world.m_broadPhase;
  for (let f = this.m_fixtureList; f; f = f.m_next) {
- for (let i = 0; i < f.m_proxies.length; ++i) {
+ for (let i = 0; i < f.m_proxyCount; ++i) {
  broadPhase.touchProxy(f.m_proxies[i].proxyId);
  }
  }

src/dynamics/Fixture.ts

@@ -128,6 +128,8 @@ export class Fixture {
  /** @internal */ m_shape: Shape;
  /** @internal */ m_next: Fixture | null;
  /** @internal */ m_proxies: FixtureProxy[];
+ // 0 indicates inactive state, this is not the same as m_proxies.length
+ /** @internal */ m_proxyCount: number;
  /** @internal */ m_userData: unknown;
 
  constructor(body: Body, def: FixtureDef);
@@ -162,7 +164,10 @@ export class Fixture {
  this.m_next = null;
 
  this.m_proxies = [];
+ this.m_proxyCount = 0;
 
+ // fixture proxies are created here,
+ // but they are activate in when a fixture is added to body
  const childCount = this.m_shape.getChildCount();
  for (let i = 0; i < childCount; ++i) {
  this.m_proxies[i] = new FixtureProxy(this, i);
@@ -367,12 +372,12 @@ export class Fixture {
  * These support body activation/deactivation.
  */
  createProxies(broadPhase: BroadPhase, xf: TransformValue): void {
- _ASSERT && console.assert(this.m_proxies.length == 0);
+ _ASSERT && console.assert(this.m_proxyCount == 0);
 
  // Create proxies in the broad-phase.
- const childCount = this.m_shape.getChildCount();
+ this.m_proxyCount = this.m_shape.getChildCount();
 
- for (let i = 0; i < childCount; ++i) {
+ for (let i = 0; i < this.m_proxyCount; ++i) {
  const proxy = this.m_proxies[i];
  this.m_shape.computeAABB(proxy.aabb, xf, i);
  proxy.proxyId = broadPhase.createProxy(proxy.aabb, proxy);
@@ -381,22 +386,21 @@ export class Fixture {
 
  destroyProxies(broadPhase: BroadPhase): void {
  // Destroy proxies in the broad-phase.
- for (let i = 0; i < this.m_proxies.length; ++i) {
+ for (let i = 0; i < this.m_proxyCount; ++i) {
  const proxy = this.m_proxies[i];
  broadPhase.destroyProxy(proxy.proxyId);
  proxy.proxyId = null;
- proxy.fixture = null;
  }
 
- this.m_proxies.length = 0;
+ this.m_proxyCount = 0;
  }
 
  /**
  * Updates this fixture proxy in broad-phase (with combined AABB of current and
  * next transformation).
  */
  synchronize(broadPhase: BroadPhase, xf1: TransformValue, xf2: TransformValue): void {
- for (let i = 0; i < this.m_proxies.length; ++i) {
+ for (let i = 0; i < this.m_proxyCount; ++i) {
  const proxy = this.m_proxies[i];
  // Compute an AABB that covers the swept shape (may miss some rotation
  // effect).
@@ -477,7 +481,7 @@ export class Fixture {
 
  // Touch each proxy so that new pairs may be created
  const broadPhase = world.m_broadPhase;
- for (let i = 0; i < this.m_proxies.length; ++i) {
+ for (let i = 0; i < this.m_proxyCount; ++i) {
  broadPhase.touchProxy(this.m_proxies[i].proxyId);
  }
  }