Merge pull request #152 from dli7319/ballpit

Ballpit: Create and destroy rigidbodies as needed.

Author: dli7319

demos/ballpit/BallShooter.js

@@ -26,13 +26,11 @@ export class BallShooter extends xb.Script {
       this.spheres.push(sphere);
     }
 
-    const matrix = new THREE.Matrix4();
     for (let i = 0; i < this.spheres.length; i++) {
       const x = Math.random() * 2 - 2;
       const y = Math.random() * 2;
       const z = Math.random() * 2 - 2;
 
-      matrix.setPosition(x, y, z);
       this.spheres[i].position.set(x, y, z);
       if (palette != null) {
         this.spheres[i].material.color.copy(palette.getRandomLiteGColor());
@@ -69,20 +67,10 @@ export class BallShooter extends xb.Script {
     colliderActiveEvents = 0,
     continuousCollisionDetection = false,
   }) {
-    for (let i = 0; i < this.spheres.length; ++i) {
-      const position = this.spheres[i].position;
-      const desc = RAPIER.RigidBodyDesc.dynamic()
-        .setTranslation(...position)
-        .setCcdEnabled(continuousCollisionDetection);
-      const body = blendedWorld.createRigidBody(desc);
-      const shape = RAPIER.ColliderDesc.ball(
-        this.spheres[i].geometry.parameters.radius
-      ).setActiveEvents(colliderActiveEvents);
-      const collider = blendedWorld.createCollider(shape, body);
-      this.colliderHandleToIndex.set(collider.handle, i);
-      this.rigidBodies.push(body);
-      this.colliders.push(collider);
-    }
+    this.RAPIER = RAPIER;
+    this.blendedWorld = blendedWorld;
+    this.colliderActiveEvents = colliderActiveEvents;
+    this.continuousCollisionDetection = continuousCollisionDetection;
   }
 
   /**
@@ -100,23 +88,46 @@ export class BallShooter extends xb.Script {
     ball.position.copy(position);
     ball.scale.setScalar(1.0);
     ball.opacity = 1.0;
-    if (this.rigidBodies.length > 0) {
-      const body = this.rigidBodies[this.nextBall];
-      body.setTranslation(position);
-      body.setLinvel(velocity);
-    }
+    this._createRigidBody(
+      this.nextBall,
+      position,
+      velocity,
+      ball.geometry.parameters.radius
+    );
     this.spawnTimes[this.nextBall] = now;
     this.nextBall = (this.nextBall + 1) % this.spheres.length;
     this.add(ball);
   }
 
+  _createRigidBody(index, position, velocity, radius) {
+    // Delete existing body if one already exists for this index
+    if (this.rigidBodies[index] != null) {
+      const existingBody = this.rigidBodies[index];
+      this.blendedWorld.removeRigidBody(existingBody);
+    }
+
+    // Create new body
+    const desc = this.RAPIER.RigidBodyDesc.dynamic()
+      .setTranslation(position.x, position.y, position.z)
+      .setLinvel(velocity.x, velocity.y, velocity.z)
+      .setCcdEnabled(this.continuousCollisionDetection);
+    const body = this.blendedWorld.createRigidBody(desc);
+    const shape = this.RAPIER.ColliderDesc.ball(radius).setActiveEvents(
+      this.colliderActiveEvents
+    );
+    const collider = this.blendedWorld.createCollider(shape, body);
+    this.colliderHandleToIndex.set(collider.handle, index);
+    this.rigidBodies[index] = body;
+    this.colliders[index] = collider;
+  }
+
   physicsStep(now = performance.now()) {
     for (let i = 0; i < this.spheres.length; i++) {
       const sphere = this.spheres[i];
       const body = this.rigidBodies[i];
       let spawnTime = this.spawnTimes[i];
 
-      if (this.isBallActive(i)) {
+      if (this.isBallActive(i) && body != null) {
         let ballVisibility = 1.0;
         const position = sphere.position.copy(body.translation());
         // If the ball falls behind the depth then adjust the spawnTime to begin
@@ -165,20 +176,15 @@ export class BallShooter extends xb.Script {
           ballVisibility = 1.0 - deflateAmount;
         }
 
-        body.setTranslation(position);
         sphere.material.opacity = ballVisibility;
 
         if (ballVisibility < 0.001) {
-          sphere.material.opacity = 0.0;
-          sphere.scale.setScalar(0);
-          position.set(0.0, -1000.0, 0.0);
-          body.setTranslation(position);
           this.removeBall(i);
+        } else {
+          sphere.position.copy(body.translation());
+          sphere.quaternion.copy(body.rotation());
         }
       }
-
-      sphere.position.copy(body.translation());
-      sphere.quaternion.copy(body.rotation());
     }
   }
 
@@ -188,9 +194,14 @@ export class BallShooter extends xb.Script {
 
   removeBall(index) {
     const ball = this.spheres[index];
+    ball.material.opacity = 0.0;
+    ball.scale.setScalar(0);
     const body = this.rigidBodies[index];
-    ball.position.set(0.0, -1000.0, 0.0);
-    body.setTranslation(ball.position);
+    if (body != null) {
+      this.blendedWorld.removeRigidBody(body);
+      this.rigidBodies[index] = null;
+      this.colliders[index] = null;
+    }
     this.remove(ball);
   }