60 lines
1.4 KiB
GLSL
60 lines
1.4 KiB
GLSL
//Noise generation code taken from https://github.com/ashima/webgl-noise/blob/master/src/classicnoise2D.glsl
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vec4 mod289(vec4 x)
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{
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return x - floor(x * (1.0 / 289.0)) * 289.0;
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}
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vec4 permute(vec4 x)
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{
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return mod289(((x*34.0)+1.0)*x);
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}
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vec4 taylorInvSqrt(vec4 r)
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{
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return 1.79284291400159 - 0.85373472095314 * r;
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}
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vec2 fade(vec2 t) {
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return t*t*t*(t*(t*6.0-15.0)+10.0);
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}
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// Classic Perlin noise
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float cnoise(vec2 P)
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{
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vec4 Pi = floor(P.xyxy) + vec4(0.0, 0.0, 1.0, 1.0);
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vec4 Pf = fract(P.xyxy) - vec4(0.0, 0.0, 1.0, 1.0);
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Pi = mod289(Pi); // To avoid truncation effects in permutation
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vec4 ix = Pi.xzxz;
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vec4 iy = Pi.yyww;
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vec4 fx = Pf.xzxz;
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vec4 fy = Pf.yyww;
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vec4 i = permute(permute(ix) + iy);
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vec4 gx = fract(i * (1.0 / 41.0)) * 2.0 - 1.0 ;
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vec4 gy = abs(gx) - 0.5 ;
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vec4 tx = floor(gx + 0.5);
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gx = gx - tx;
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vec2 g00 = vec2(gx.x,gy.x);
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vec2 g10 = vec2(gx.y,gy.y);
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vec2 g01 = vec2(gx.z,gy.z);
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vec2 g11 = vec2(gx.w,gy.w);
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vec4 norm = taylorInvSqrt(vec4(dot(g00, g00), dot(g01, g01), dot(g10, g10), dot(g11, g11)));
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g00 *= norm.x;
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g01 *= norm.y;
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g10 *= norm.z;
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g11 *= norm.w;
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float n00 = dot(g00, vec2(fx.x, fy.x));
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float n10 = dot(g10, vec2(fx.y, fy.y));
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float n01 = dot(g01, vec2(fx.z, fy.z));
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float n11 = dot(g11, vec2(fx.w, fy.w));
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vec2 fade_xy = fade(Pf.xy);
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vec2 n_x = mix(vec2(n00, n01), vec2(n10, n11), fade_xy.x);
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float n_xy = mix(n_x.x, n_x.y, fade_xy.y);
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return 2.3 * n_xy;
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}
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