CODEWITHSUNDEEP
sprite-kitskfieldnode
Z3lda
Z3lda

Reputation: 21

SpriteKit SKFieldNode: Why can't I move the field during runtime?

I am trying to move a SKFieldNode (radialGravity) during runtime:

let movingField = SKFieldNode.radialGravityField(
movingField.position = location  //location is a touch position
addChild(movingField)

It crashes as soon as I command the field node to change positions. I have no problem placing the field node in a static position at didMoveToView.

I'm guessing SKFieldNodes simply have to stay in place, but maybe theres a solution.

The main idea is to attach the radial fields to sprites (which have physics bodies attached) so that they have attraction/repulsion interactions. I realize this can be done in a more manual approach, but I was trying to take advantage of the physics available in SpriteKit.

Thanks!

Upvotes: 2

Views: 475

Answers (2)

sven7
sven7

Reputation: 748

In my app I have a very similar approach like you. I can set new positions of field nodes just fine. Here is an excerpt:

// _targetPos is the touch location in UIView coordinates
CGPoint pos = [k.world convertToScenePoint:_targetPos]; // convert to scene coordinates
self.gravityField.position = pos;
self.dragField.position = pos;

I can only assume the crash you have mentioned occurs somewhere else in your code. Which line of code does Xcode show when your app crashes?

Upvotes: 0

Patrick Collins
Patrick Collins

Reputation: 4334

I can easily move field nodes by making them move to follow touch events. Works fine.

Inside of GameScene.m

-(void)didMoveToView:(SKView *)view {
    /* Setup your scene here */

    self.backgroundColor = SKColorWithRGB(0, 0, 0);

    // This uses SKTUtils to load my simple SKEmitter
    SKEmitterNode *nd = [SKEmitterNode skt_emitterNamed:@"bokeh"];
    nd.particleZPosition += 100;
    nd.position = CGPointMake(self.size.width/2,self.size.height/2);
    nd.fieldBitMask = 1;

    field = [SKFieldNode radialGravityField];

    field.position = CGPointMake(self.size.width/2,self.size.height/2);;
    field.minimumRadius = 50;
    field.categoryBitMask = 1;

    [self addChild:field];
    [self addChild:nd];

}

-(void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event {
    UITouch *touch = [touches anyObject];
    CGPoint t = [touch locationInNode:self];
    field.position = t;
}

Upvotes: 2

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