Sine Wave Motion In SpriteKit

Question

I want to make sine wave motion from the first point in the screen to the last Point in the screen, independent on the size of the screen.

Here is my code, but it d

Answer 1

This is an old post but I wanted to post an answer to make it google-able. I made this function in a subclass of SKSpriteNode that made the sprite go in an approximated sine wave from one side to the other.

It's in swift, but could be easily done in objective C. Also, you'd want to be more intelligent and put the path building in a loop, but I just kept it unlooped to make the math easy to understand.

(I don't disagree with the game loop answer but it kind of goes against the philosophy of Sprite Kit)

func setSineAction()
{
    let scene = self.parent as! SKScene

    let y42 = scene.size.height/2
    let x1 = scene.size.width
    let x2 = scene.size.width * 0.875
    let x3 = scene.size.width * 0.750
    let x4 = scene.size.width * 0.625
    let x5 = scene.size.width * 0.500
    let x6 = scene.size.width * 0.375
    let x7 = scene.size.width * 0.250
    let x8 = scene.size.width * 0.125
    let x9 = 0.0 as CGFloat

    let path = CGPathCreateMutable();
    CGPathMoveToPoint(path, nil, x1, y42)
    CGPathAddQuadCurveToPoint(path, nil, (x1/2)+(x2/2), scene.size.height*0.7, x2, y42)
    CGPathAddQuadCurveToPoint(path, nil, (x2/2)+(x3/2), scene.size.height*0.3, x3, y42)
    CGPathAddQuadCurveToPoint(path, nil, (x3/2)+(x4/2), scene.size.height*0.7, x4, y42)
    CGPathAddQuadCurveToPoint(path, nil, (x4/2)+(x5/2), scene.size.height*0.3, x5, y42)
    CGPathAddQuadCurveToPoint(path, nil, (x5/2)+(x6/2), scene.size.height*0.7, x6, y42)
    CGPathAddQuadCurveToPoint(path, nil, (x6/2)+(x7/2), scene.size.height*0.3, x7, y42)
    CGPathAddQuadCurveToPoint(path, nil, (x7/2)+(x8/2), scene.size.height*0.7, x8, y42)
    CGPathAddQuadCurveToPoint(path, nil, (x8/2)+(x9/2), scene.size.height*0.3, x9, y42)

    self.runAction(SKAction.followPath(path, asOffset: false, orientToPath: false, duration: 10))

}