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shadertoy/shaders/remember/remember.frag.msl

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#include <metal_stdlib>
using namespace metal;
// Remember — diatribes
// MSL port of remember.vk.glsl.
struct ShadertoyUBO {
float iTime;
float2 iResolution;
};
struct PassthroughVOut {
float4 pos [[position]];
float2 uv;
};
static float hash12(float2 p) {
float3 p3 = fract(float3(p.xyx) * 0.1031);
p3 += dot(p3, p3.yzx + 33.33);
return fract((p3.x + p3.y) * p3.z);
}
fragment float4 remember_fs(PassthroughVOut in [[stage_in]],
constant ShadertoyUBO& U [[buffer(0)]]) {
float2 fragCoord = in.uv * U.iResolution;
float2 u = fragCoord;
float3 q, p = float3(U.iResolution, U.iResolution.x / U.iResolution.y);
float i = 0.0, s = 0.0;
float d = 0.125 * hash12(u);
float t = U.iTime * 0.1;
u = (u + u - p.xy) / p.y;
if (abs(u.y) > 0.8) { return float4(0); }
float4 o = float4(0.0);
for (; i < 64.0; i++) {
q = p = float3(u * d, d + t * 5.0);
// mat2(cos(.1*p.z+.1*t+vec4(0,33,11,0))) — column-major: (m00,m10,m01,m11)
float4 cs = cos(0.1 * p.z + 0.1 * t + float4(0, 33, 11, 0));
float2x2 m = float2x2(cs.x, cs.y, cs.z, cs.w);
p.xy = p.xy * m;
q.xz = cos(q.xz);
p.z = cos(p.z);
for (s = 1.0; s++ < 6.0;) {
q += sin(0.6 * t + p.zxy * 0.6);
p += sin(t + t + p.yzx * s) * 0.6;
}
s = 0.02 + abs(min(length(p + 3.0 * sin(p.z * 0.5)) - 4.0, length(q - 2.0 * sin(p.z * 0.4)) - 6.0)) * 0.2;
d += s;
float4 brightTerm = min(0.01 * float4(6, 2, 1, 0) / max(length(u * sin(t + t + t)), 0.001), float4(50.0));
o += brightTerm + 1.0 / s * length(u);
}
o = tanh(max(o / 6e2 + dot(u, u) * 0.35, 0.0));
return o;
}