76 lines
2.2 KiB
Plaintext
76 lines
2.2 KiB
Plaintext
#include <metal_stdlib>
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using namespace metal;
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// Cineshader Lava — edankwan
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// MSL port of cineshader_lava.vk.glsl.
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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 float opSmoothUnion(float d1, float d2, float k) {
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float h = clamp(0.5 + 0.5 * (d2 - d1) / k, 0.0, 1.0);
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return mix(d2, d1, h) - k * h * (1.0 - h);
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}
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static float sdSphere(float3 p, float s) {
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return length(p) - s;
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}
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static float map(float3 p, float iTime) {
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float d = 2.0;
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for (int i = 0; i < 16; i++) {
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float fi = float(i);
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float time = iTime * (fract(fi * 412.531 + 0.513) - 0.5) * 2.0;
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d = opSmoothUnion(
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sdSphere(p + sin(time + fi * float3(52.5126, 64.62744, 632.25)) * float3(2.0, 2.0, 0.8),
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mix(0.5, 1.0, fract(fi * 412.531 + 0.5124))),
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d,
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0.4
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);
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}
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return d;
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}
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static float3 calcNormal(float3 p, float iTime) {
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const float h = 1e-5;
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const float2 k = float2(1, -1);
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return normalize(k.xyy * map(p + k.xyy * h, iTime) +
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k.yyx * map(p + k.yyx * h, iTime) +
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k.yxy * map(p + k.yxy * h, iTime) +
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k.xxx * map(p + k.xxx * h, iTime));
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}
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fragment float4 cineshader_lava_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 uv = fragCoord / U.iResolution;
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float3 rayOri = float3((uv - 0.5) * float2(U.iResolution.x / U.iResolution.y, 1.0) * 6.0, 3.0);
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float3 rayDir = float3(0.0, 0.0, -1.0);
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float depth = 0.0;
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float3 p = float3(0.0);
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for (int i = 0; i < 64; i++) {
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p = rayOri + rayDir * depth;
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float dist = map(p, U.iTime);
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depth += dist;
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if (dist < 1e-6) { break; }
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}
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depth = min(6.0, depth);
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float3 n = calcNormal(p, U.iTime);
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float b = max(0.0, dot(n, float3(0.577)));
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float3 col = (0.5 + 0.5 * cos((b + U.iTime * 3.0) + uv.xyx * 2.0 + float3(0, 2, 4))) * (0.85 + b * 0.35);
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col *= exp(-depth * 0.15);
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return float4(col, 1.0 - (depth - 0.5) / 2.0);
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}
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