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Flutter - Flame engine | collision: When an object have a high velocity/speed the collision don't trigger

I did some test and I saw when an object have a high velocity/speed the collision don't trigger.

On the Flame docs it notes:

Do note that the built-in collision detection system does not take collisions between two hitboxes that overshoot each other into account, this could happen when they either move too fast or update being called with a large delta time (for example if your app is not in the foreground). This behaviour is called tunneling, if you want to read more about it. I would love to see something talking about that and how we can avoid that!There is a good approach for that type of thing?

I realize something with some other test.

If angle are modified, it will trigger the collision. (I don't know why it won't whiteout that)

The update function (that modify the Y value) look like that:

@override
  void update(double dt) {
    super.update(dt);
    y = y + _speedY * dt - _GRAVITY * dt * dt / 2;
    _speedY += _GRAVITY * dt;
    angle = velocityAngle(_speedY);
  }

Example:

On that gif you can see the cube have a shape (HitboxRectangle) and the green floor too. But collider don't trigger. Only trigger if I "Jump" on the hitbox.

enter image description here

P.S. the laggy visual/animation is only because its a gif

EDIT: I realize something with some other test.

If angle are modified, have a better chance to trigger the collision. Looks like it simply works now. (I don't know why)

Imagine you got a function that return an angle base on your true current angle on the update and you add a randomise number to add on micro variation on your current angle.

The angle randomiser is so small that is not even visible. (At least on a canvas square)

...
var rng = (new Random().nextInt(4) - 2) / 1000;
return angle + rng;

I don't really like that weird solution.. but it works! Maybe it could helps to discover the why and a better solution.

Solution

  • There was a bug in rc9 regarding the collision detection, this should work fine in rc10 (or rc11 which we are releasing today). Your components are not moving fast enough to miss the whole collision check.

    Do note that in your pubspec-file you can't specify ^1.0.0-rc10 because pub treats rc10 as lower than rc10, so you have to specifically say 1.0.0-rc10 (without the ^).

    EDIT: rc11 is now released so now you can use ^ again:

    dependencies:
  ...
  flame: ^1.0.0-releasecandidate.11