iOS - SpriteKit : ApplyImpulse not working on SKSpriteNode

Question

I'm kind of new with SpriteKit and I'm having some troubles with the physics, I've tried many things to make a SKSpriteNode move with a force or an impulse but it never moves, only gravity affects it when i set it.

-(id)initWithSize:(CGSize)size {
    if (self = [super initWithSize:size]) {

        self.anchorPoint = CGPointMake(0.5, 0.5);
        myWorld = [SKNode node];
        [self addChild:myWorld];

        SKSpriteNode* map = [SKSpriteNode spriteNodeWithImageNamed:@"grass"];
        [myWorld addChild:map];

        self.physicsBody = [SKPhysicsBody bodyWithEdgeLoopFromRect:map.frame];
        self.physicsBody.friction = 0.0f;
        self.physicsBody.categoryBitMask = 2;
        self.physicsWorld.gravity = CGVectorMake(0.0, 0.0);
        self.physicsWorld.contactDelegate = self;

        pointOfView = [SKSpriteNode spriteNodeWithColor:[UIColor colorWithWhite:1 alpha:0.2] size:CGSizeMake(300, 548)];
        [myWorld addChild:pointOfView];

        pointOfView.physicsBody = [SKPhysicsBody bodyWithRectangleOfSize:pointOfView.frame.size];
        pointOfView.physicsBody.friction = 0.0f;
        pointOfView.physicsBody.restitution = 1.0f;
        pointOfView.physicsBody.linearDamping = 0.0f;
        pointOfView.physicsBody.allowsRotation = NO;
        pointOfView.physicsBody.collisionBitMask = 2;
        pointOfView.physicsBody.categoryBitMask = 3;
        [pointOfView.physicsBody applyImpulse:CGVectorMake(10.0f, -10.0f)];
    }
    return self;
}

Here is most of my code in my main scene, there's nothing else except some empty methods like update or touchesBegan.. Am I missing something ? I've tried so many things, i'm starting to lose it haha

Thanks very much for any help !

you have written wrong code your pointOfView no affected by gravity you are just applying a small impusle on it. — dragoneye, Oct 17 '14 at 05:31

score 1 · Answer 1 · edited May 23 '17 at 10:27

1

It's a bit late, but the answer is here: Not able to apply impulse to SKSpriteNode physics body

The problem is that you've created a physics body with bodyWithEdgeLoopFromRect; this creates a static physics body which won't respond to applyImpulse. You need to add the physics body using bodyWithRectangleOfSize: instead.

edited May 23 '17 at 10:27

Community

1
1

answered Mar 29 '15 at 16:49

Uzziel

300
2
6

score 0 · Answer 2 · answered Oct 17 '14 at 14:32

0

pointOfView.physicsBody.dynamic = YES;

The dynamic property decides if a sprite should be affected by physics forces.

answered Oct 17 '14 at 14:32

meisenman

1,818
1
15
25

I've already tried this but it doesn't work.. :( Plus according to the official doc, this property is by default set to Yes, as i'm not setting it to No, I shouldn't need to specify it.. – user3198930 Oct 20 '14 at 13:50

score -1 · Answer 3 · answered Oct 17 '14 at 05:35

-1

you have written wrong code your pointOfView not affected by gravity you are just applying a small impusle on it.

change this line self.physicsWorld.gravity = CGVectorMake(0.0, 0.0) to self.physicsWorld.gravity = CGVectorMake(0.0, -9.8); if u looking for negative gravity towards up direction and CGVectorMake(0.0, 9.8) if you looking for positive gravity towards downwards. and try to apply impulse after a interval [pointOfView.physicsBody applyImpulse:CGVectorMake(10.0f, -10.0f)];

answered Oct 17 '14 at 05:35

dragoneye

703
6
14

Unfortunately, i'm not looking to apply gravity to my node, on the contrary i've already tried it and it's working, what's not working is this small impusle you're talking about, the node doesn't move at all.. – user3198930 Oct 20 '14 at 13:47

iOS - SpriteKit : ApplyImpulse not working on SKSpriteNode

3 Answers3