24 lines
No EOL
781 B
Text
24 lines
No EOL
781 B
Text
/*
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contributors: Inigo Quiles
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description: generate the SDF of a octogon prism
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use: <float> octogonPrismSDF( <float3> p, <float> r, <float> h )
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*/
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#ifndef FNC_OCTOGONPRISMSDF
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#define FNC_OCTOGONPRISMSDF
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float octogonPrismSDF( float3 p, float r, float h ) {
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float3 k = float3( -0.9238795325, // sqrt(2+sqrt(2))/2
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0.3826834323, // sqrt(2-sqrt(2))/2
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0.4142135623 ); // sqrt(2)-1
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// reflections
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p = abs(p);
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p.xy -= 2.0*min(dot(float2( k.x,k.y),p.xy),0.0)*float2( k.x,k.y);
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p.xy -= 2.0*min(dot(float2(-k.x,k.y),p.xy),0.0)*float2(-k.x,k.y);
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// polygon side
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p.xy -= float2(clamp(p.x, -k.z*r, k.z*r), r);
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float2 d = float2( length(p.xy)*sign(p.y), p.z-h );
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return min(max(d.x,d.y),0.0) + length(max(d,0.0));
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}
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#endif |