27 lines
879 B
Plaintext
27 lines
879 B
Plaintext
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vec2 octahedronWrap(vec2 _val)
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{
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// Reference(s):
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// - Octahedron normal vector encoding
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// https://web.archive.org/web/20191027010600/https://knarkowicz.wordpress.com/2014/04/16/octahedron-normal-vector-encoding/comment-page-1/
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return (1.0 - abs(_val.yx) )
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* mix(vec2_splat(-1.0), vec2_splat(1.0), vec2(greaterThanEqual(_val.xy, vec2_splat(0.0) ) ) );
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}
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vec2 EncodeNormal(vec3 _normal)
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{
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_normal /= abs(_normal.x) + abs(_normal.y) + abs(_normal.z);
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_normal.xy = _normal.z >= 0.0 ? _normal.xy : octahedronWrap(_normal.xy);
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_normal.xy = _normal.xy * 0.5 + 0.5;
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return _normal.xy;
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}
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vec3 DecodeNormal(vec2 _encodedNormal)
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{
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_encodedNormal = _encodedNormal * 2.0 - 1.0;
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vec3 normal;
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normal.z = 1.0 - abs(_encodedNormal.x) - abs(_encodedNormal.y);
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normal.xy = normal.z >= 0.0 ? _encodedNormal.xy : octahedronWrap(_encodedNormal.xy);
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return normalize(normal);
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}
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