30 lines
876 B
Text
30 lines
876 B
Text
#include "../math/const.msl"
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/*
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contributors: Patricio Gonzalez Vivo
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description: Returns a sdf for a regular polygon with V sides.
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use: polySDF(<float2> st, int V)
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options:
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- CENTER_2D: float2, defaults to float2(.5)
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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_POLYSDF
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#define FNC_POLYSDF
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float polySDF(float2 st, int V) {
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#ifdef CENTER_2D
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st -= CENTER_2D;
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st *= 2.0;
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#else
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st = st * 2.0 - 1.0;
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#endif
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float a = atan(st.x, st.y) + PI;
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float r = length(st);
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float v = TAU / float(V);
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return cos(floor(.5 + a / v) * v - a ) * r;
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}
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#endif
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