Matter-js: Check if world is sleeping

[codeclown]

First of all, simply amazing work on the library and maintainment, bravo!

Question: is there a built-in method/event to detect when the world is still/sleeping, as in there is no movement on any body? I'm aware it can be detected for bodies individually.

[liabru]

Nothing built in for this, I'd suggest something like:

let bodies = Composite.allBodies(world);
let sleeping = bodies.filter((body) => body.isSleeping);
let isWorldSleeping = bodies.length === sleeping.length;

[codeclown]

Thank you for the answer!

[codeclown]

@liabru Another question. Isn't isSleeping === true supposed to mean that a body has stopped movement? In my tests bodies actually never end up in this state.

I'm simply trying to detect when all objects in the world have stopped moving.

[codeclown]

Okay, it simply seems that, while being invisible to the eye, the objects actually maintain just a tiny amount of speed. What I did for now:

let isAwake = false;
const bodies = Matter.Composite.allBodies(world);

for(let i = 0; i < bodies.length; i++) {
    if(bodies[i].speed > 0.005) {
        isAwake = true;
        break;
    }
}

if(!isAwake) {
    for(let i = 0; i < bodies.length; i++) {
        Matter.Body.setVelocity(bodies[i], { x: 0, y: 0 });
    }
}

Maybe there is a more elegant solution?

[liabru]

Do you mean actual sleeping, which you have to enable or do you just mean 'come to rest'? If it's the latter then try something like this in the filter:

let motion = body.speed * body.speed + body.angularSpeed * body.angularSpeed;
let isResting = motion < 0.1;

[codeclown]

I meant detecting when all objects/bodies have stopped moving. My bad on confusing the terms. Thank you again.