Sprite Kit Physicsbody.Resting Behavior

Sprite Kit physicsBody.resting behavior

If you examine the velocity of a physics body, you'll see that it is indeed moving but at a rate that is not perceivable. That's why the resting property is not set. A more reliable way to check if a SKPhysicsBody is at rest is to test if its linear and angular speeds are nearly zero. Here's an example of how to do that:

func speed(velocity:CGVector) -> Float {
    let dx = Float(velocity.dx);
    let dy = Float(velocity.dy);
    return sqrtf(dx*dx+dy*dy)
}

func angularSpeed(velocity:CGFloat) -> Float {
    return abs(Float(velocity))
}

// This is a more reliable test for a physicsBody at "rest"
func nearlyAtRest(node:SKNode) -> Bool {
    return (self.speed(node.physicsBody.velocity)<self.verySmallValue
        && self.angularSpeed(node.physicsBody.angularVelocity) < self.verySmallValue)
}

override func update(_ currentTime: TimeInterval) {
    /* Enumerate over child nodes with names starting with "circle" */
    enumerateChildNodesWithName("circle*") {
        node, stop in
        if (node.physicsBody.resting) {
            println("\(node.name) is resting")
        }
        if (self.nearlyAtRest(node)) {
            println("\(node.name) is nearly resting")
        }
    }
}

SpriteKit - Detect if sprite still moving/stopped

You can check physics body velocity vector to see if the node is moving in any direction. With something like this you would be probably fine :

if((yournode.physicsBody.velocity.dx == 0.0f) && (yournode.physicsBody.velocity.dy == 0.0f)) {
   //do your stuff
}

Also there is a property on node's physics body called resting which indicates whether the object is at rest within the physics simulation. So you could probably do something like this:

if(yourNode.physicsBody.resting ) {
 //do your stuff
 }

You can read about certain behaviours and recommendations about resting property in this SO answer.

Hope this helps

Sprite Kit Collision without bouncing

Had the same issue just a minute ago. It works with setting the restitution but you need to set both restitutions. The one of the hero AND the one of the platform (or in my case the scene boundaries).

so:

hero.physicsBody.collisionBitMask = platformCategory
hero.physicsBody.restitution = 0.0
platform.physicsBody.restitution = 0.0
any_other_object_that_should_still_bounce.physicsBody.restitution = 1.0

will do it. All other objects on the screen still bounce on the platform as long as you set their restitution > 0

Apple's Swift Sprite Kit: linearDamping, how is this property used mathematically?

The formula for Box2D is velocity *= 1.0f / (1.0f + time * linearDamping);

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