41 SwiftUI Metal shaders. Holographic foil, kaleidoscope mandalas, magnetic fields, glitch, neon edges, and a pile more. Each one is a [[ stitchable ]] Metal function with a typed SwiftUI View modifier wrapped around it, so dropping one onto a view is a single line.

These started as a hidden shader lab inside Epilogue, my reading app. I built way more than I ever shipped, so I pulled the good ones out to share. Every shader here got rendered on a real book cover and kept only if it actually looked good. The duds, the washed-out ones, and the ones that only work on a blank gradient got cut. What's left is the set I'd reach for myself.

Drop them into your own project and mess around. They're also built to hand straight to a coding agent like Claude Code or Codex. If one sparks an idea, point your agent at AGENTS.md and let it riff.

Want to dial them in by eye? Hand the repo to your agent and ask it to build a slider-based tuning tool. Everything it needs is in Docs/parameters.json, and the recipe is in AGENTS.md. Tune against your own content, copy the line it spits out, paste it into your code.

The bcs_ prefix is just the shader namespace. Nothing here is wired to Epilogue's actual app code.

• iOS 17+ / macOS 14+ / tvOS 17+ / visionOS 1+
• Xcode 15+ (the Metal toolchain compiles the shaders into the package's default.metallib)

One gotcha: build with Xcode or xcodebuild, not bare swift build. SwiftPM's command-line driver on macOS doesn't run the Metal toolchain, so Bundle.module and default.metallib never get produced. In Xcode it just works.

Swift Package Manager. In Xcode, go to File ▸ Add Package Dependencies and point it at this repo's URL. Or add it in Package.swift:

.package(url: "https://github.com/krispuckett/SwiftUIShaders.git", from: "1.0.0")

Then add SwiftUIShaders to your target's dependencies.

import SwiftUI
import SwiftUIShaders

struct ContentView: View {
    var body: some View {
        Image("book-cover")
            .resizable()
            .scaledToFit()
            .bcsHolographic(intensity: 0.6, scale: 12, speed: 1.2)  // animated, self-driving
    }
}

Every shader is a View modifier. The animated ones run themselves with TimelineView(.animation), so there's no timer for you to babysit. Every parameter has a sensible default, so .bcsKaleidoscope() works on its own.

Text("Chapter One")
    .font(.largeTitle)
    .bcsChromaticSplit(spread: 8, angle: .pi / 4)

bookCover
    .bcsAurora()             // ambient animated glow

myView
    .bcsEmboss(strength: 3)  // static relief

One heads up: these want real content. Photos, book covers, illustrations, text. Drop one on a flat single-color fill and the displacement and edge effects have nothing to grab onto.

Each wrapper applies one Metal layerEffect. The mapping is uniform:

Every method also takes maxSampleOffset: (default 64×64). Raise it if a heavy displacement effect looks clipped at the edges. Lower it for a small perf win on cheap effects.

37 animate. 4 are static (bcsEmboss, bcsFrosted, and the two interaction-driven ripples). Ranges in parentheses are the sweet spots. The defaults are tuned values that look good out of the box, so you can call any of these with no arguments and get something real.

bcsTouchRipple and bcsRefractLens take a touchPos: UnitPoint. Feed them a drag location for a touch-reactive effect, and use a GeometryReader to normalize the point:

@State private var touch: UnitPoint = .center

GeometryReader { geo in
    myView
        .bcsRefractLens(touchPos: touch, lensRadius: 0.3)
        .gesture(DragGesture(minimumDistance: 0).onChanged { v in
            touch = UnitPoint(x: v.location.x / geo.size.width,
                              y: v.location.y / geo.size.height)
        })
}

• These are GPU fragment effects. Most are cheap, but the blur and displacement-heavy ones (bcsFrosted, bcsShatterGlass, bcsMagneticField) sample a lot of neighbors, so profile before you stack them on big, fast-scrolling views.
• Animated shaders re-render every frame while they're on screen. Don't leave dozens running off-screen.
• half-precision is used throughout for speed. Expect a little banding at extreme parameter values.

MIT. See LICENSE. Use them, ship them, remix them. Attribution's appreciated, never required.