96 lines
2.7 KiB
Plaintext
96 lines
2.7 KiB
Plaintext
#include <metal_stdlib>
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using namespace metal;
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// Octograms — whisky_shusuky
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// MSL port of octograms.vk.glsl. The Shadertoy original uses a mutable
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// file-scope `gTime`; in MSL we pass it as a parameter through the chain.
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struct ShadertoyUBO {
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float iTime;
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float2 iResolution;
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};
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struct PassthroughVOut {
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float4 pos [[position]];
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float2 uv;
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};
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static float2x2 rot(float a) {
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float c = cos(a), s = sin(a);
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return float2x2(c, s, -s, c);
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}
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static float sdBox(float3 p, float3 b) {
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float3 q = abs(p) - b;
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return length(max(q, float3(0.0))) + min(max(q.x, max(q.y, q.z)), 0.0);
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}
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static float boxGeom(float3 pos, float scale) {
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pos *= scale;
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float base = sdBox(pos, float3(0.4, 0.4, 0.1)) / 1.5;
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pos.xy = (pos.xy * 5.0 - float2(0.0, 3.5)) * rot(0.75);
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return -base;
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}
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static float box_set(float3 pos, float gTime) {
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float3 pos_origin = pos;
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pos = pos_origin;
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pos.y += sin(gTime * 0.4) * 2.5;
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pos.xy = pos.xy * rot(0.8);
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float box1 = boxGeom(pos, 2.0 - abs(sin(gTime * 0.4)) * 1.5);
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pos = pos_origin;
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pos.y -= sin(gTime * 0.4) * 2.5;
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pos.xy = pos.xy * rot(0.8);
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float box2 = boxGeom(pos, 2.0 - abs(sin(gTime * 0.4)) * 1.5);
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pos = pos_origin;
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pos.x += sin(gTime * 0.4) * 2.5;
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pos.xy = pos.xy * rot(0.8);
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float box3 = boxGeom(pos, 2.0 - abs(sin(gTime * 0.4)) * 1.5);
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pos = pos_origin;
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pos.x -= sin(gTime * 0.4) * 2.5;
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pos.xy = pos.xy * rot(0.8);
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float box4 = boxGeom(pos, 2.0 - abs(sin(gTime * 0.4)) * 1.5);
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pos = pos_origin;
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pos.xy = pos.xy * rot(0.8);
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float box5 = boxGeom(pos, 0.5) * 6.0;
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pos = pos_origin;
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float box6 = boxGeom(pos, 0.5) * 6.0;
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return max(max(max(max(max(box1, box2), box3), box4), box5), box6);
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}
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fragment float4 octograms_fs(PassthroughVOut in [[stage_in]],
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constant ShadertoyUBO& U [[buffer(0)]]) {
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float2 fragCoord = in.uv * U.iResolution;
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float2 p = (fragCoord * 2.0 - U.iResolution) / min(U.iResolution.x, U.iResolution.y);
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float3 ro = float3(0.0, -0.2, U.iTime * 4.0);
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float3 ray = normalize(float3(p, 1.5));
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ray.xy = ray.xy * rot(sin(U.iTime * 0.03) * 5.0);
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ray.yz = ray.yz * rot(sin(U.iTime * 0.05) * 0.2);
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float t = 0.1;
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float ac = 0.0;
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for (int i = 0; i < 99; i++) {
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float3 pos = ro + ray * t;
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pos = fract((pos - 2.0) / 4.0) * 4.0 - 2.0;
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float gTime = U.iTime - float(i) * 0.01;
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float d = box_set(pos, gTime);
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d = max(abs(d), 0.01);
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ac += exp(-d * 23.0);
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t += d * 0.55;
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}
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float3 col = float3(ac * 0.02);
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col += float3(0.0, 0.2 * abs(sin(U.iTime)), 0.5 + sin(U.iTime) * 0.2);
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return float4(col, 1.0 - t * (0.02 + 0.02 * sin(U.iTime)));
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}
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