I have an oval UIBezierPath with a moving SKSpriteNode,
I stop its motion and record the stopped position. I then restart this motion and want it to restart where it initially stopped.
Works great if motion is not stopped. Movement is great around entire oval Path.
Also works great as long as this stop-restart sequence occurs along the top half of the oval UIBezierPath. However, I have problems along the bottom half of this Path -- it stops okay, but the restart position is not where it previously stopped.
My method to create this oval UIBezierePath is as follows:
func createTrainPath() {
trainRect = CGRect(x: tracksPosX - tracksWidth/2,
y: tracksPosY - tracksHeight/2,
width: tracksWidth,
height: tracksHeight)
// these methods come from @DonMag
trainPoints = generatePoints(inRect: trainRect,
withNumberOfPoints: nbrPathPoints)
trainPath = generatePathFromPoints(trainPoints!,
startingAtIDX: savedTrainIndex)
} // createTrainPath
My method to stop this motion is as follows:
func stopFollowTrainPath() {
guard (myTrain != nil) else { return }
myTrain.isPaused = true
savedTrainPosition = myTrain.position
// also from @DonMag
savedTrainIndex = closestIndexInPath(
trainPath,
toPoint: savedTrainPosition) ?? 0
} // stopFollowTrainPath
Finally, I call this to re-start this motion:
func startFollowTrainPath() {
var trainAction = SKAction.follow(trainPath.cgPath,
asOffset: false,
orientToPath: true,
speed: thisSpeed)
trainAction = SKAction.repeatForever(trainAction)
myTrain.run(trainAction, withKey: runTrainKey)
myTrain.isPaused = false
} // startFollowTrainPath
Again, great if motion is not stopped. Movement is great around entire oval Path.
Again, no problem for stopping and then restarting along top half of oval .. the ohoh occurs along bottom half.
Is there something I need to do within GameScene's update method that I am missing? For example, do I need to reconstruct my UIBezierPath? every time my node moves between the top half and the bottom half and therein account for the fact that the node is traveling in the opposite direction from the top half?
Topic:
Graphics & Games
SubTopic:
SpriteKit