Ripple Effect

Metal.shader

#include <metal_stdlib>
#include <SwiftUI/SwiftUI.h>
using namespace metal;
 
[[ stitchable ]] half4 simpleripple(float2 pos, SwiftUI::Layer l, float4 boundingRect, float time) {

    float2 size = boundingRect.zw;
    float2 uv = pos / size;
    float2 center = float2(0.5,0.5);
    float aspectratio = size.x / size.y;


    float speed = 0.1;
    float amplitude = 14;
    float frequency = 6;
    float decay = 0.1;

    float2 diff = uv - center;
    diff.x *= aspectratio;
    float distance = length(diff);
    float delay = distance / speed;
    time = max(0.0, time - delay);

    float rippleAmount = amplitude * sin(frequency * time) * exp(-decay * time);
    float2 n = normalize(uv - center);
    float2 newpos = uv * size;
    newpos += rippleAmount * n;

    half4 color= l.sample(newpos);
    color.rgb += 0.3 * (rippleAmount / amplitude) * color.a;
    return color;

}