gistlib - create a bubbly relaxing interactive fluid to play with on swiftui in swift in swift

To create a bubbly relaxing interactive fluid in SwiftUI, we can use fluid dynamics and a particle system. Here are the steps to create the fluid:

Create a Particle struct to hold the particle's position, velocity, and acceleration.


main.swift
struct Particle {
    var x: CGFloat
    var y: CGFloat
    var vx: CGFloat
    var vy: CGFloat
    var ax: CGFloat
    var ay: CGFloat
}
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Create a Fluid struct to hold the properties of the fluid, including the particles.


main.swift
struct Fluid {
    var particles: [Particle]
    var viscosity: CGFloat
    var drag: CGFloat
    var gravity: CGFloat
}
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Initialize the particles with random positions, velocities, and accelerations.
Update the position, velocity, and acceleration of each particle based on the fluid's properties and any user input.


main.swift
func updateParticles(_ fluid: inout Fluid, _ touchLocation: CGPoint?) {
    for i in 0..<fluid.particles.count {
        let p = fluid.particles[i]
        
        // Calculate forces
        var fx = -fluid.viscosity * p.vx
        var fy = -fluid.viscosity * p.vy + fluid.gravity
        
        if let touch = touchLocation {
            // Apply attraction force towards the user's touch location
            let dx = touch.x - p.x
            let dy = touch.y - p.y
            let distanceSq = dx*dx + dy*dy
            let distance = sqrt(distanceSq)
            let strength = min(200 / distanceSq, 2)
            fx += strength * dx / distance
            fy += strength * dy / distance
        }
        
        // Update velocity
        let ax = (fx + fluid.drag * -p.vx) / 1.2
        let ay = (fy + fluid.drag * -p.vy) / 1.2
        let vx = p.vx + ax
        let vy = p.vy + ay
        
        // Update position
        let x = p.x + vx
        let y = p.y + vy
        
        fluid.particles[i] = Particle(x: x, y: y, vx: vx, vy: vy, ax: ax, ay: ay)
    }
}
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Render the particles using SwiftUI's Path and Circle shapes.


main.swift
struct ContentView: View {
    @State var fluid = createFluid()
    @State var touchLocation: CGPoint?
    
    var body: some View {
        GeometryReader { geometry in
            Path { path in
                for p in fluid.particles {
                    path.addPath(Circle(center: CGPoint(x: p.x, y: p.y), radius: 10))
                }
            }
            .fill(Color.blue.opacity(0.5))
            .gesture(
                DragGesture()
                    .onChanged { value in
                        touchLocation = value.location
                    }
                    .onEnded { _ in
                        touchLocation = nil
                    }
            )
            .onAppear {
                let timer = Timer.scheduledTimer(withTimeInterval: 1/60, repeats: true) { timer in
                    updateParticles(&fluid, touchLocation)
                }
                RunLoop.current.add(timer, forMode: .common)
            }
        }
    }
}
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This will create a fluid that can be interacted with using touch input, with particles that move and react to external forces like gravity and viscosity.

create a bubbly relaxing interactive fluid to play with on swiftui in swift in swift

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