├── SlowRipple.swift
└── metal.metal


/SlowRipple.swift:
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 1 | 
 2 | import SwiftUI
 3 | 
 4 | struct SlowRipple: View {
 5 |     @State private var time : CGFloat = 0.1
 6 |     @State private var noise : CGFloat = 4
 7 |     @State private var strength : CGFloat = 1
 8 |     @State private var dragp : CGPoint = .zero
 9 | 
10 |     private let timer = Timer.publish(every: 1/120,
11 |                                      on: .main,
12 |                                      in: .common).autoconnect()
13 |     @State private var angle : CGFloat = 0
14 | 
15 |     
16 |     var body: some View {
17 |         ZStack{
18 |             ZStack{
19 |                 LinearGradient(colors: [.brown.mix(with: .black, by: 0.8), .orange, .white], startPoint: .top, endPoint: .bottomTrailing)
20 |                     .frame(width:360,height:300)
21 |                     .blur(radius: 20)
22 |                     .layerEffect(ShaderLibrary.fbp(.boundingRect,.float2(dragp),.float(time), .float(noise), .float(strength)), maxSampleOffset: CGSize(width:200,height: 200))
23 | 
24 |                 Color.black.opacity(0.3)
25 |                 VStack{
26 |                     Spacer()
27 |                     HStack{
28 |                         Text("time : \(time, specifier: "%.2f") /")
29 |                         Text("noise : \(noise, specifier: "%.2f") /")
30 |                         Text("strength : \(strength, specifier: "%.2f")")
31 |                         Spacer()
32 |                     }
33 |                     
34 |                 }
35 |                 .frame(width:330, height: 260)
36 |                 .foregroundStyle(.white)
37 |                 .font(.system(size: 10, design: .monospaced))
38 |                 
39 |             }
40 |             .frame(width:360,height:300)
41 |             .cornerRadius(12)
42 |             .shadow(radius: 8)
43 | 
44 |             VStack{
45 |                 Spacer()
46 |                 Slider(value: $time, in:0...1)
47 |                 Slider(value: $noise, in:0...8)
48 |                 Slider(value: $strength, in:0...10)
49 | 
50 |             }
51 |             .tint(.primary)
52 |             .padding()
53 |             .onReceive(timer) { _ in
54 |                 angle += 0.001
55 | 
56 |                 dragp = CGPoint(
57 |                     x: 5 + cos(angle) * 300,
58 |                     y: 5 + sin(angle) * 300
59 |                 )
60 | 
61 |             }
62 | 
63 | 
64 |         }
65 | 
66 |     }
67 | }
68 | 


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/metal.metal:
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 1 | //
 2 | //  Metal.metal
 3 | //  SwiftMay21
 4 | //
 5 | //  Created by Minsang Choi on 5/21/25.
 6 | //
 7 | 
 8 | #include <metal_stdlib>
 9 | #include <SwiftUI/SwiftUI.h>
10 | using namespace metal;
11 | 
12 | float random(float2 st) {
13 |     return fract(sin(dot(st.xy, float2(12.9898, 78.233))) * 43758.5453123);
14 | }
15 | 
16 | 
17 | float value_noise(float2 st) {
18 |     float2 i = floor(st);
19 |     float2 f = fract(st);
20 | 
21 |     float a = random(i);
22 |     float b = random(i + float2(1.0, 0.0));
23 |     float c = random(i + float2(0.0, 1.0));
24 |     float d = random(i + float2(1.0, 1.0));
25 | 
26 | 
27 |     float2 u = f * f * f * (f * (f * 6.0 - 15.0) + 10.0);
28 | 
29 | 
30 |     return mix(mix(a, b, u.x),
31 |                mix(c, d, u.x), u.y);
32 | }
33 | 
34 | 
35 | [[ stitchable ]] half4 fbp(float2 pos, SwiftUI::Layer l, float4 boundingBox, float2 dragp, float time, float noise, float strength) {
36 |     
37 |     float2 size = float2(boundingBox[2],boundingBox[3]);
38 |     float2 uv = pos / size;
39 |     float2 c = dragp / size;
40 |     
41 |     
42 |     float noiseScale = noise;
43 |     float rippleFrequency = 16.0;
44 |     float rippleSpeed = 3.0;
45 |     float noisePerturbation = strength;
46 |     float displacementStrength = 0.3;
47 | 
48 |     float baseNoise = value_noise(uv * noiseScale);
49 | 
50 |      float2 rippleCenter = c; // Moving center
51 | 
52 |     float dist = distance(uv, rippleCenter);
53 |     float rippleWave = sin(
54 |         dist * rippleFrequency        // Wavefronts based on distance
55 |         - time * rippleSpeed          // Animation over time
56 |         + baseNoise * noisePerturbation // Noise perturbs the phase
57 |     );
58 |     float2 direction = normalize(uv - rippleCenter + 1e-5);
59 |     float2 displacement = direction * rippleWave * displacementStrength;
60 |     float2 displacedUv = uv + displacement;
61 | 
62 |     float finalPattern = value_noise(displacedUv * noiseScale * 1.2 + float2(time * 0.1, 0.0)); // Slightly different scale/animation for the sampled pattern
63 |     float shading = smoothstep(0.0, 0.8, rippleWave) * 0.5 + 0.5;
64 |     
65 |     
66 |     float2 newpos = uv;
67 |     newpos *= finalPattern * shading;
68 |     half4 color = l.sample(newpos * size);
69 |     
70 |     return color;
71 | }
72 | 


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