SKShader to create parallax background

Question

A parallax background with a fixed camera is easy to do, but since i'm making a topdown view 2D space exploration game, I figured that having a single SKSpriteNode filling the screen and being a child of my SKCameraNode and using a SKShader to draw a parallax starfield would be easier.

I went on shadertoy and found this simple looking shader. I adapted it successfully on shadertoy to accept a vec2() for the velocity of the movement that I want to pass as an SKAttribute so it can follow the movement of my ship.

Here is the original source: https://www.shadertoy.com/view/XtjSDh

I managed to make the conversion of the original code so it compiles without any error, but nothing shows up on the screen. I tried the individual functions and they do work to generate a fixed image.

Any pointers to make it work?

Thanks!

Answer 1

EDIT : Code is clean and working now. I've setup a GitHub repo for this.

I guess I didnt explain what I wanted properly. I needed a starfield background that follows the camera like you could find in Subspace (back in the days)

The result is pretty cool and convincing! I'll probably come back to this later when the node quantity becomes a bottleneck. I'm still convinced that the proper way to do that is with shaders!

Here is a link to my code on GitHub. I hope it can be useful to someone. It's still a work in progress but it works well. Included in the repo is the source from SKTUtils (a library by Ray Wenderlich that is already freely available on github) and from my own extension to Ray's tools that I called nuts-n-bolts. these are just extensions for common types that everyone should find useful. You, of course, have the source for the StarfieldNode and the InteractiveCameraNode along with a small demo project.

• https://github.com/sonoblaise/StarfieldDemo

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