I have a Swift / SpriteKit game in which a whole bunch of sprites have physics bodies to detect collision with the player - but otherwise they are not supposed to move.
My issue is that as soon as I add a physics body, the sprite appears to move fractionally. More specifically its position changes by a small fraction (like 0.0003). Initially such a small change does not matter, but it keeps changing like this until the sprite actually moves onscreen and messes up the game.
To narrow it down I created a simple project with just one sprite and I notice that as soon as I attach a physics body to my sprite its position shifts fractionally.
Things I've already tried:
- Check so see gravity is turned off
- Set the resting property of physics body to true
- set the affected by gravity property of physics body to false
Im coding using Xcode on OS X
But no luck.
Here's a code fragment which shows this in the test project:
import SpriteKit
class TestScene: SKScene, SKPhysicsContactDelegate {
let sprite1 = SKSpriteNode(color: SKColor.redColor(), size: CGSizeMake(50, 50))
override func didMoveToView(view: SKView) {
physicsWorld.gravity = CGVectorMake(0.0, 0.0)
physicsWorld.contactDelegate = self
sprite1.position = CGPointMake(200, 200)
sprite1.physicsBody = SKPhysicsBody(rectangleOfSize: sprite1.size)
sprite1.physicsBody?.affectedByGravity = false
sprite1.physicsBody?.resting = true
self.addChild(sprite1)
sprite1.position = CGPointMake(200, 200)
}
override func update(currentTime: NSTimeInterval) {
print(sprite1.position)
// position is not 200,200 as expected
// it becomes 199.999938964844, 199.999938964844 after a few updates
// In my real project the position will keep drifting like this until it moves on screen
}
}
