39 lines
No EOL
922 B
GLSL
39 lines
No EOL
922 B
GLSL
/*
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contributors: Inigo Quiles
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description: generate the SDF of a octahedron
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use: <float> octahedronSDF(<vec3> p, <float> s)
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options:
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OCTAHEDRON_EXACT_DISTANCE
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*/
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#ifndef FNC_OCTAHEDRONSDF
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#define FNC_OCTAHEDRONSDF
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float octahedronSDF(vec3 p, float s) {
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p = abs(p);
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float m = p.x + p.y + p.z - s;
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#ifdef OCTAHEDRON_EXACT_DISTANCE
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// exact distance
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vec3 o = min(3.0*p - m, 0.0);
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o = max(6.0*p - m*2.0 - o*3.0 + (o.x+o.y+o.z), 0.0);
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return length(p - s*o/(o.x+o.y+o.z));
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// #elif OCTAHEDRON_EXACT_DISTANCE == 2
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// // exact distance
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// vec3 q = vec3(0.0);
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// if( 3.0*p.x < m ) q = p.xyz;
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// else if( 3.0*p.y < m ) q = p.yzx;
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// else if( 3.0*p.z < m ) q = p.zxy;
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// else return m*0.57735027;
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// float k = clamp(0.5*(q.z-q.y+s),0.0,s);
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// return length(vec3(q.x,q.y-s+k,q.z-k));
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#else
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// bound, not exact
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return m*0.57735027;
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#endif
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}
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#endif |