Metal water

water-shader.metal

// https://twitter.com/zozuar/status/1632160439944478721?s=42&t=kZ3wyx2jn4JBuVn3WNWeYQ

fragment float4 waterShader(const VertexOut vertexOut [[stage_in]],
                             constant Uniforms& uniforms [[buffer(0)]]) {

    float height, iteration, amplitude, waveLength, xCoord, globalWaveHeight;

    // Initialize variables
    height = vertexOut.position.y;
    iteration = 0.0;
    amplitude = uniforms.amplitude;
    waveLength = uniforms.waveLength;
    xCoord = (vertexOut.position.x / uniforms.resolution.y) * uniforms.scale;
    globalWaveHeight = uniforms.globalWaveHeight - 3.0;

    // Iterate over waves
    for (; iteration++ < 100.0;) {
        // Calculate position of current wave
        float3 position = float3(vertexOut.position.xy / uniforms.resolution.y * globalWaveHeight, globalWaveHeight, 0.0);
        position.yz *= float3x3(rotationMatrix(0.0, 0.6, 0.0));

        // Adjust position based on wave amplitude and frequency
        for (amplitude = 0.8; amplitude > 0.003; amplitude *= 0.8) {
            position.xz *= float3x3(rotationMatrix(0.0, 5.0, 0.0));
            xCoord = (++position.x + position.z) / amplitude + uniforms.time * 2.0;
            float waveHeight = exp(sin(xCoord) - 2.5) * amplitude;
            uniforms.color.gb += waveHeight / 400.0;
            position.xz -= float2(waveHeight * cos(xCoord), waveHeight);
            height -= waveHeight;
        }

        globalWaveHeight += height;
    }

    // Calculate final color based on wave height and frequency
    uniforms.color += min(height * height * 4e6, 1.0 / globalWaveHeight) + globalWaveHeight * globalWaveHeight / 200.0;
    return uniforms.color;
}