36 lines
1 KiB
Text
36 lines
1 KiB
Text
#include "../math/const.msl"
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#include "../space/scale.msl"
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/*
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contributors: Patricio Gonzalez Vivo
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description: Returns a star-shaped sdf with V branches
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use: starSDF(<float2> st, <int> V, <float> scale)
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examples:
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- https://raw.githubusercontent.com/patriciogonzalezvivo/lygia_examples/main/draw_shapes.frag
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license:
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- Copyright (c) 2021 Patricio Gonzalez Vivo under Prosperity License - https://prosperitylicense.com/versions/3.0.0
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- Copyright (c) 2021 Patricio Gonzalez Vivo under Patron License - https://lygia.xyz/license
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*/
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#ifndef FNC_STARSDF
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#define FNC_STARSDF
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float starSDF(float2 st, int V, float s) {
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#ifdef CENTER_2D
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st -= CENTER_2D;
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#else
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st -= 0.5;
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#endif
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st *= 2.0;
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float a = atan(st.y, st.x) / TAU;
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float seg = a * float(V);
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a = ((floor(seg) + 0.5) / float(V) +
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mix(s, -s, step(0.5, fract(seg))))
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* TAU;
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return abs(dot(float2(cos(a), sin(a)),
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st));
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}
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float starSDF(float2 st, int V) {
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return starSDF( scale(st, 12.0/float(V)), V, 0.1);
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}
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#endif
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