Improve collision handlers: add separated before and after collision …

…handlers

examples/common/bootstrap.js

@@ -398,11 +398,6 @@ export class Bootstrap extends EventEmitter {
         const t = performance.now();
         if (this.state !== State.pause) {
             this.#physicsStep(this.#stats.elapsed / 1000);
-
-            for (const collision of this.#solver.stepInfo.collisions) {
-                collision.aBody.collider.onCollide(collision, collision.bBody);
-                collision.bBody.collider.onCollide(collision, collision.aBody);
-            }
         }
 
         if (this.state === State.step) {
@@ -416,6 +411,12 @@ export class Bootstrap extends EventEmitter {
         this.#stats.collisionCount = this.#solver.stepInfo.collisionCount;
         this.#stats.checkCount = this.#solver.stepInfo.checkCount;
 
+        for (const body of this.rigidBodies) {
+            if (body.destroyed) {
+                this.#destroyBodyImpl(body);
+            }
+        }
+
         requestAnimationFrame(timestamp => {
             this.#stats.elapsed = timestamp - this.#stats.lastStepTime;
             this.#stats.lastStepTime = timestamp;

examples/particles/index.js

@@ -44,7 +44,7 @@ class SmokeCollider extends CircleCollider {
         return !(body2.collider instanceof SmokeCollider);
     }
 
-    onCollide(collision, body2) {
+    afterCollision(collision, body2) {
         if (body2.tag === Tags.world) {
             this.particle.setState(SmokeState.destroy);
         }

examples/snow/objects/misc.js

@@ -36,7 +36,7 @@ export class SnowdriftCollider extends PolygonCollider {
         this.#onCollideHandler = onCollideFn;
     }
 
-    onCollide(collision, body2) {
+    afterCollision(collision, body2) {
         this.#onCollideHandler(collision, this.body, body2);
     }
 }
@@ -49,7 +49,7 @@ export class WorldBorderCollider extends Collider {
         this.#engine = engine;
     }
 
-    onCollide(collision, body2) {
+    afterCollision(collision, body2) {
         if (body2.tag === Tags.snowflake) {
             this.#engine.destroyBody(body2);
         }
@@ -116,7 +116,7 @@ export class SmokeCollider extends CircleCollider {
         return SmokeCollider.#NoCollideTags.indexOf(body2.tag) === -1;
     }
 
-    onCollide(collision, body2) {
+    afterCollision(collision, body2) {
         if (body2.tag === Tags.worldBorder && !this.#particle.destroyed) {
             this.#particle.setState(SmokeState.destroy);
         }

lib/physics/body/base.js

@@ -16,6 +16,7 @@ export class Body {
     collider;
     _active = true;
     _static = false;
+    _destroyed = false;
 
     _id = 0;
     _mass = 0;
@@ -134,6 +135,7 @@ export class Body {
     get tag() {return this._tag;}
     get active() {return this._static ? false : this._active;}
     get static() {return this._static;}
+    get destroyed() {return this._destroyed;}
 
     get mass() {return this.active ? this._mass : 1e12;}
     set mass(value) {this.setMass(value);}
@@ -193,6 +195,8 @@ export class Body {
      * @param {Vector2} point
      */
     applyImpulse(impulse, point) {
+        if (this.destroyed) return;
+
         this.velocity.add(impulse.scaled(this.invertedMass));
         this.angularVelocity += point.delta(this.position).cross(impulse) * this.invertedInertia;
     }
@@ -202,7 +206,7 @@ export class Body {
      * @param {Vector2} point
      */
     applyPseudoImpulse(impulse, point) {
-        if (!this.active) return;
+        if (!this.active || this.destroyed) return;
 
         this.position.add(impulse);
         this.angle += point.delta(this.position).cross(impulse) * this.invertedInertia;
@@ -213,7 +217,7 @@ export class Body {
      * @param {number} rotation
      */
     applyVelocity(velocity, rotation) {
-        if (!this.active) return;
+        if (!this.active || this.destroyed) return;
 
         this.position.add(velocity);
         this.angle += rotation;
@@ -223,4 +227,8 @@ export class Body {
             this.angle = this.angle - 2 * Math.PI * scale;
         }
     }
+
+    destroy() {
+        this._destroyed = true;
+    }
 }

lib/physics/collider/base.js

@@ -50,11 +50,18 @@ export class Collider {
         return Collider.detectBoundaryCollision(this.body.boundary, body2.boundary);
     }
 
+
+    /**
+     * @param {Collision} collision
+     * @param {Body} body2
+     */
+    beforeCollision(collision, body2) {}
+
     /**
      * @param {Collision} collision
      * @param {Body} body2
      */
-    onCollide(collision, body2) {}
+    afterCollision(collision, body2) {}
 
     /**
      * @param {Body} body2

lib/physics/solver.js

@@ -135,6 +135,11 @@ export class ImpulseBasedSolver {
             }
         }
 
+        for (const collision of this.stepInfo.collisions) {
+            collision.aBody.collider.afterCollision(collision, collision.bBody);
+            collision.bBody.collider.afterCollision(collision, collision.aBody);
+        }
+
         if (this.debug) {
             for (const info of this.#collisionInfos) {
                 if (this.debug.showNormalVector) {
@@ -182,8 +187,16 @@ export class ImpulseBasedSolver {
         this.#processTreeLeaf(this.stepInfo.tree.root);
 
         for (const collision of this.stepInfo.collisions) {
+            collision.aBody.collider.beforeCollision(collision, collision.bBody);
+            collision.bBody.collider.beforeCollision(collision, collision.aBody);
+        }
+
+        for (const collision of this.stepInfo.collisions) {
+            if (collision.aBody.destroyed || collision.bBody.destroyed) continue;
+
             this.#collisionInfos.push(this.#prepareCollisionInfo(collision));
         }
+
         this.stepInfo.collisionCount = this.stepInfo.collisions.length;
         this.stepInfo.collisionTime = performance.now() - t;
     }