73 lines
3.3 KiB
HLSL
73 lines
3.3 KiB
HLSL
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// The MIT License (MIT) (see LICENSE.txt)
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// Copyright © 2015 Inigo Quilez
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// Copyright © 2021 Jens Neitzel
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// One simple way to avoid texture tile repetition, at the cost of 4 times the amount of
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// texture lookups (still much better than https://www.shadertoy.com/view/4tsGzf)
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//
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// More info: http://www.iquilezles.org/www/articles/texturerepetition/texturerepetition.htm
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struct NoTileUVs
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{
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fixed4 ofa, ofb, ofc, ofd;
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fixed2 uva, uvb, uvc, uvd, b;
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fixed2 ddxa, ddxb, ddxc, ddxd;
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fixed2 ddya, ddyb, ddyc, ddyd;
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};
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fixed4 hash4( fixed2 p ) { return frac(sin(fixed4( 1.0+dot(p,fixed2(37.0,17.0)),
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2.0+dot(p,fixed2(11.0,47.0)),
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3.0+dot(p,fixed2(41.0,29.0)),
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4.0+dot(p,fixed2(23.0,31.0))))*103.0); }
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NoTileUVs textureNoTileCalcUVs( in fixed2 uv )
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{
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NoTileUVs ntuvs;
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fixed2 iuv = floor( uv );
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fixed2 fuv = frac( uv );
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// generate per-tile transform
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ntuvs.ofa = hash4( iuv + fixed2(0,0) );
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ntuvs.ofb = hash4( iuv + fixed2(1,0) );
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ntuvs.ofc = hash4( iuv + fixed2(0,1) );
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ntuvs.ofd = hash4( iuv + fixed2(1,1) );
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fixed2 uvddx = ddx( uv );
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fixed2 uvddy = ddy( uv );
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// transform per-tile uvs
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ntuvs.ofa.zw = sign(ntuvs.ofa.zw-0.5);
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ntuvs.ofb.zw = sign(ntuvs.ofb.zw-0.5);
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ntuvs.ofc.zw = sign(ntuvs.ofc.zw-0.5);
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ntuvs.ofd.zw = sign(ntuvs.ofd.zw-0.5);
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// uv's, and derivatives (for correct mipmapping)
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ntuvs.uva = uv*ntuvs.ofa.zw + ntuvs.ofa.xy; ntuvs.ddxa = uvddx*ntuvs.ofa.zw; ntuvs.ddya = uvddy*ntuvs.ofa.zw;
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ntuvs.uvb = uv*ntuvs.ofb.zw + ntuvs.ofb.xy; ntuvs.ddxb = uvddx*ntuvs.ofb.zw; ntuvs.ddyb = uvddy*ntuvs.ofb.zw;
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ntuvs.uvc = uv*ntuvs.ofc.zw + ntuvs.ofc.xy; ntuvs.ddxc = uvddx*ntuvs.ofc.zw; ntuvs.ddyc = uvddy*ntuvs.ofc.zw;
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ntuvs.uvd = uv*ntuvs.ofd.zw + ntuvs.ofd.xy; ntuvs.ddxd = uvddx*ntuvs.ofd.zw; ntuvs.ddyd = uvddy*ntuvs.ofd.zw;
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// fetch and blend
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ntuvs.b = smoothstep(0.25, 0.75, fuv);
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return ntuvs;
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}
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fixed4 textureNoTile( sampler2D samp, in NoTileUVs ntuvs )
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{
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// Use modified UVs to sample a texture
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return lerp( lerp( tex2D( samp, ntuvs.uva, ntuvs.ddxa, ntuvs.ddya ),
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tex2D( samp, ntuvs.uvb, ntuvs.ddxb, ntuvs.ddyb ), ntuvs.b.x ),
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lerp( tex2D( samp, ntuvs.uvc, ntuvs.ddxc, ntuvs.ddyc ),
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tex2D( samp, ntuvs.uvd, ntuvs.ddxd, ntuvs.ddyd ), ntuvs.b.x ), ntuvs.b.y );
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}
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fixed3 textureNoTileNormal( sampler2D sampNorm, in NoTileUVs ntuvs, in half normalScale )
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{
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// Use modified UVs to sample a normal map, also inverting red and green channels where needed due to mirroring
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return lerp( lerp( fixed3( ntuvs.ofa.z, ntuvs.ofa.w, 1 ) * UnpackNormalWithScale( tex2D( sampNorm, ntuvs.uva, ntuvs.ddxa, ntuvs.ddya ), normalScale ),
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fixed3( ntuvs.ofb.z, ntuvs.ofb.w, 1 ) * UnpackNormalWithScale( tex2D( sampNorm, ntuvs.uvb, ntuvs.ddxb, ntuvs.ddyb ), normalScale ), ntuvs.b.x ),
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lerp( fixed3( ntuvs.ofc.z, ntuvs.ofc.w, 1 ) * UnpackNormalWithScale( tex2D( sampNorm, ntuvs.uvc, ntuvs.ddxc, ntuvs.ddyc ), normalScale ),
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fixed3( ntuvs.ofd.z, ntuvs.ofd.w, 1 ) * UnpackNormalWithScale( tex2D( sampNorm, ntuvs.uvd, ntuvs.ddxd, ntuvs.ddyd ), normalScale ), ntuvs.b.x ), ntuvs.b.y );
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}
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