44 lines
No EOL
1.2 KiB
Text
44 lines
No EOL
1.2 KiB
Text
#include "../math/pow2.msl"
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/*
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contributors: Kathy McGuiness
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description: |
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Returns the Juia set SDF
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For more information about the Julia set, check [this article](https://en.wikipedia.org/wiki/Julia_set)
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Some values for c:
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* float2(−0.8, 0.156)
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* float2(0.285, 0.0)
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* float2(-0.8, 0.156);
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* float2(0.27334, 0.00742)
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* float2(−0.835, −0.2321)
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use: juliaSDF(<float2> st, <float2> c, <float> r)
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examples:
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- https://gist.githubusercontent.com/kfahn22/246988bac1f346c3112a8ea1cd0b114d/raw/8f3a563e3c88cbbfb267a0277ba9b262a9e63570/julia.frag
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*/
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#ifndef FNC_JULIASDF
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#define FNC_JULIASDF
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float juliaSDF( float2 st, float2 center, float2 c, float r) {
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st -= 0.5;
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st *= 2.0;
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float2 z = float2(0.0) - (st) * r;
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float n = 0.0;
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const int I = 500;
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for (int i = I; i > 0; i--) {
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if ( length(z) > 4.0 ) {
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n = float(i)/float(I);
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break;
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}
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z = float2( (pow2(z.x) - pow2(z.y)) + c.x, (2.0*z.x*z.y) + c.y );
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}
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return n;
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}
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float juliaSDF( float2 st, float2 c, float r) {
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#ifdef CENTER_2D
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return juliaSDF(st, CENTER_2D, c, r);
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#else
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return juliaSDF(st, float2(0.5), c, r);
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#endif
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}
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#endif |