recursive use of an object detected which would lead to unsafe aliasing in rust

Using rapier2d-compat version 0.7.6

// World contains some static and dynamic body
world.forEachRigidBody(body =>{
  const collidersLength = body.numColliders();

  for (let i = 0; i < collidersLength; i++) {
    const collider = world.getCollider(body.collider(i));
    drawBody(ctx, collider, body);
  }

  if (body.bodyType() === RAPIER.RigidBodyType.Static) {
    return
  }

  const bodyPosition = body.translation();

  const bodyMass = body.mass();

  world.forEachRigidBody(otherBody => {
    if (body.handle === otherBody.handle) {
      return
    }

    const otherBodyMass = otherBody.mass();

    const otherBodyPosition = otherBody.translation();

    const distance = getDistance(otherBodyPosition, bodyPosition);

    const forceDirection = getDirection(
      otherBodyPosition,
      bodyPosition
    );
    const forceMagnitude = getGravitationalForce(
      otherBodyMass,
      bodyMass,
      distance
    );
    try {
      body.applyForce(
        new RAPIER.Vector2(
          (Math.sin(forceDirection) * forceMagnitude) /
            Math.sqrt(bodyMass),
          (Math.cos(forceDirection) * forceMagnitude) /
            Math.sqrt(bodyMass)
        ),
        true
      );
    } catch (error) {
      console.error(error);
    }
  })
})

This code always throws as soon as I have 2 bodies (1 static & 1 dynamic, 2 statics, 2 dynamics, whatever) with the error recursive use of an object detected which would lead to unsafe aliasing in rust.

The error also happens with forEachRigidBodyHandle

The same code using forEachCollider works (but I wanna use forEachRigidBody because some bodies have multiple colliders)

world.forEachCollider((collider) => {
  const body = world.getRigidBody(collider.parent());

  drawBody(ctx, collider, body);

  if (body.bodyType() === RAPIER.RigidBodyType.Static) {
    return;
  }

  const bodyPosition = body.translation();

  const bodyMass = body.mass();

  world.forEachCollider((otherCollider) => {
    const otherBody = world.getRigidBody(otherCollider.parent());

    if (body.handle === otherBody.handle) {
      return;
    }

    const otherBodyMass = otherBody.mass();

    const otherBodyPosition = otherBody.translation();

    const distance = getDistance(otherBodyPosition, bodyPosition);

    const forceDirection = getDirection(
      otherBodyPosition,
      bodyPosition
    );
    const forceMagnitude = getGravitationalForce(
      otherBodyMass,
      bodyMass,
      distance
    );
    try {
      body.applyForce(
        new RAPIER.Vector2(
          (Math.sin(forceDirection) * forceMagnitude) /
            Math.sqrt(bodyMass),
          (Math.cos(forceDirection) * forceMagnitude) /
            Math.sqrt(bodyMass)
        ),
        true
      );
    } catch (error) {
      console.error(error);
    }
  });
});

[LeXXik]

Ah, of course, you are right on that one. Completely forgot about the event callbacks 😅 I am scheduling all event updates to the next simulation step, thats why I don’t have it. I wonder why Ammo doesn’t crash, though 🤔 I guess there is some safety mechanism in place to prevent it.

[racer161]

@jcyuan I found out I was starting a new runtime loop before I finished the last due to async/await. So this was indeed the problem. thanks!