From the GameFromScartch site: "Right off the hop, that title is a bit misleading… Phaser doesn’t really support GLSL shaders, or at least not by that name. What it supports is Filters, which it inherits from the Pixi renderer. Right off the hop you should be aware that this only works on the WebGL renderer, so the fallback canvas renderer cannot and probably never will support filters."
This process isn’t overly difficult, but as far as I’ve been able to tell, there are no existing examples on using shaders/filters in Phaser with Typescript, so a few of the TypeScript specific aspects can cause a bit of a stumbling block."