43 lines
No EOL
1.3 KiB
Text
43 lines
No EOL
1.3 KiB
Text
#include "../space/cart2polar.msl"
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/*
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contributors: Kathy McGuiness
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description: |
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Returns the mandelbulb SDF
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For more information about the mandlebulb, check [this article](https://en.wikipedia.org/wiki/Mandelbulb)
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use: mandelbulbSDF(<float2> st)
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examples:
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- https://gist.githubusercontent.com/kfahn22/4c29e6d2bdc33d639f315edaa934d287/raw/0eb94683614995476fb63cfa99881e420f1c5be6/mandelbulb.frag
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*/
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#ifndef FNC_MANDELBULBSDF
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#define FNC_MANDELBULBSDF
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float2 mandelbulbSDF( float3 st ) {
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float3 zeta = st;
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float m = dot(st,st);
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float dz = 1.0;
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float n = 8.0;
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const int maxiterations = 20;
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float iterations = 0.0;
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float r = 0.0;
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float dr = 1.0;
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for (int i = 0; i < maxiterations; i+=1) {
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dz = n*pow(m, 3.5)*dz + 1.0;
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float3 sphericalZ = cart2polar( zeta );
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float newx = pow(sphericalZ.x, n) * sin(sphericalZ.y*n) * cos(sphericalZ.z*n);
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float newy = pow(sphericalZ.x, n) * sin(sphericalZ.y*n) * sin(sphericalZ.z*n);
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float newz = pow(sphericalZ.x, n) * cos(sphericalZ.y*n);
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zeta.x = newx + st.x;
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zeta.y = newy + st.y;
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zeta.z = newz + st.z;
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m = dot(zeta, zeta);
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if ( m > 2.0 )
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break;
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}
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// distance estimation through the Hubbard-Douady potential from Inigo Quilez
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return float2(0.25*log(m) * sqrt(m) / dz, iterations);
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}
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#endif |