Need help figuring out Parallax background

[JensB]

Hi!
So I'm working on a 2D space shooter type of game and am trying to get a parallax background thing going. But I'm having trouble getting the math right.

You can see my work in progress here: https://www.youtube.com/watch?v=Pea9yVbTD64

As stated in the video everything works if the players x and y are positive, but breaks when they are negative, and I can't figure out what I am doing wrong. Any help would be greatly appreciated. Or perhaps there is a better way to accomplish this?

What I'm doing is randomly generating out a bunch of the Sprites, and then updating their position with this code.

_Nebulas: is Array<NebulaParticle> which is listed below as well.
p.distance: is a number between 1 and 5 to signify how far away the sprite is and is used to make them move slower when they are furher away.
_Width and _Height are both arbitrary numbers to signify how big the area is that the parallax should cover, in the video they are both set to 80.
OriginalOffsetX/Y is the original random position the Sprite was given.

public update(delta: number, playerx: number, playery: number) {
    console.log(playerx + ", " + playery );
    for (let i = 0; i < this._Nebulas.length; i++) {
        let p = this._Nebulas[i];          
        p._Sprite.x = (playerx + (this._Width / 2)) - (((playerx / p.distance) + p.OriginalOffsetX) % this._Width);
        p._Sprite.y = (playery + (this._Width / 2)) - (((playery / p.distance) + p.OriginalOffsetY) % this._Height);
    }
}

 

class NebulaParticle {
    public _Sprite: Phaser.GameObjects.Sprite;
    public OriginalOffsetX: number;
    public OriginalOffsetY: number;
    public distance: number;
}

Thank you very much.