MeshGradientTest.swift

//
//  MeshGradientTest.swift
//
//  Created by Daniel Kuntz on 6/10/24.
//

import SwiftUI

struct ContentTimerView: View {
    @State var t: Float = 0.0
    @State var timer: Timer?

    var body: some View {
        ZStack {
            AnimatedGradientView(t: t)
            Text(String(t))
        }
        .onAppear {
            timer = Timer.scheduledTimer(withTimeInterval: 0.01, repeats: true) { _ in
                t += 0.02
            }
        }
    }
}

struct ContentTimelineView: View {
    @State var t: Float = 0.0
    @State var timer: Timer?

    var body: some View {
        TimelineView(.periodic(from: Date(), by: 0.01)) { ctx in
            ZStack {
                AnimatedGradientView(t: Float(ctx.date.timeIntervalSince1970))
                Text(String(ctx.date.timeIntervalSince1970))
            }
        }
        .ignoresSafeArea()
    }
}

struct AnimatedGradientView: View {
    var t: Float

    var body: some View {
        MeshGradient(
            width: 3,
            height: 3,
            points: [
                [0.0, 0.0],
                [0.5, 0.0],
                [1.0, 0.0],

                [sinInRange(-0.8...(-0.2), 0.439, 0.342, t),  sinInRange(0.3...0.7, 3.42, 0.984, t)],
                [sinInRange(0.1...0.8,     0.239, 0.084, t),  sinInRange(0.2...0.8, 5.21, 0.242, t)],
                [sinInRange(1.0...1.5,     0.939, 0.084, t),  sinInRange(0.4...0.8, 0.25, 0.642, t)],

                [sinInRange(-0.8...0.0,    1.439, 0.442, t),  sinInRange(1.4...1.9, 3.42, 0.984, t)],
                [sinInRange(0.3...0.6,     0.339, 0.784, t),  sinInRange(1.0...1.2, 1.22, 0.772, t)],
                [sinInRange(1.0...1.5,     0.939, 0.056, t),  sinInRange(1.3...1.7, 0.47, 0.342, t)]
            ],
            colors: [
                .black, .black, .black,
                .orange, .red, .orange,
                .indigo, .black, .green
            ],
            background: .black)
        .ignoresSafeArea()
    }

    func sinInRange(_ range: ClosedRange<Float>, _ offset: Float, _ timeScale: Float, _ t: Float) -> Float {
        let amplitude = (range.upperBound - range.lowerBound) / 2
        let midPoint = (range.upperBound + range.lowerBound) / 2
        return midPoint + amplitude * sin(timeScale * t + offset)
    }
}

#Preview {
    ContentTimerView()
    ContentTimelineView()
}