49 lines
1.2 KiB
Metal
Executable File
49 lines
1.2 KiB
Metal
Executable File
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#include <metal_stdlib>
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using namespace metal;
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float random(float2 p)
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{
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return fract(sin(dot(p, float2(15.79, 81.93)) * 45678.9123));
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}
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float noise(float2 p)
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{
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float2 i = floor(p);
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float2 f = fract(p);
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f = f * f * (3.0 - 2.0 * f);
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float bottom = mix(random(i + float2(0)), random(i + float2(1.0, 0.0)), f.x);
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float top = mix(random(i + float2(0.0, 1.0)), random(i + float2(1)), f.x);
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float t = mix(bottom, top, f.y);
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return t;
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}
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float fbm(float2 uv)
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{
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float sum = 0;
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float amp = 0.7;
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for(int i = 0; i < 4; ++i)
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{
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sum += noise(uv) * amp;
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uv += uv * 1.2;
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amp *= 0.4;
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}
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return sum;
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}
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kernel void compute(texture2d<float, access::write> output [[texture(0)]],
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constant float &timer [[buffer(0)]],
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uint2 gid [[thread_position_in_grid]])
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{
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int width = output.get_width();
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int height = output.get_height();
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float2 uv = float2(gid) / float2(width, height);
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uv = uv * 2.0 - 1.0;
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float radius = 0.5;
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float distance = length(uv) - radius;
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uv = fmod(uv + float2(timer * 0.2, 0), float2(width, height));
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float t = fbm( uv * 3 );
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output.write(distance < 0 ? float4(float3(t), 1) : float4(0), gid);
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}
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