80 lines
1.9 KiB
Plaintext
80 lines
1.9 KiB
Plaintext
// Array and textureless GLSL 2D/3D/4D simplex noise functions.
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// Ported from Ashima Arts webgl-noise (MIT License).
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// https://github.com/ashima/webgl-noise
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vec3 mod289_vec3(vec3 x) {
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return x - floor(x * (1.0 / 289.0)) * 289.0;
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}
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vec4 mod289_vec4(vec4 x) {
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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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return mod289_vec4(((x * 34.0) + 1.0) * x);
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}
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vec4 taylor_inv_sqrt(vec4 r) {
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return 1.79284291400159 - 0.85373472095314 * r;
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}
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float snoise(vec3 v) {
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const vec2 C = vec2(1.0 / 6.0, 1.0 / 3.0);
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const vec4 D = vec4(0.0, 0.5, 1.0, 2.0);
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vec3 i = floor(v + dot(v, C.yyy));
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vec3 x0 = v - i + dot(i, C.xxx);
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vec3 g = step(x0.yzx, x0.xyz);
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vec3 l = 1.0 - g;
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vec3 i1 = min(g.xyz, l.zxy);
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vec3 i2 = max(g.xyz, l.zxy);
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vec3 x1 = x0 - i1 + C.xxx;
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vec3 x2 = x0 - i2 + C.yyy;
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vec3 x3 = x0 - D.yyy;
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i = mod289_vec3(i);
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vec4 p = permute(permute(permute(
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i.z + vec4(0.0, i1.z, i2.z, 1.0))
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+ i.y + vec4(0.0, i1.y, i2.y, 1.0))
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+ i.x + vec4(0.0, i1.x, i2.x, 1.0));
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float n_ = 0.142857142857;
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vec3 ns = n_ * D.wyz - D.xzx;
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vec4 j = p - 49.0 * floor(p * ns.z * ns.z);
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vec4 x_ = floor(j * ns.z);
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vec4 y_ = floor(j - 7.0 * x_);
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vec4 x = x_ * ns.x + ns.yyyy;
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vec4 y = y_ * ns.x + ns.yyyy;
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vec4 h = 1.0 - abs(x) - abs(y);
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vec4 b0 = vec4(x.xy, y.xy);
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vec4 b1 = vec4(x.zw, y.zw);
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vec4 s0 = floor(b0) * 2.0 + 1.0;
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vec4 s1 = floor(b1) * 2.0 + 1.0;
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vec4 sh = -step(h, vec4(0.0, 0.0, 0.0, 0.0));
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vec4 a0 = b0.xzyw + s0.xzyw * sh.xxyy;
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vec4 a1 = b1.xzyw + s1.xzyw * sh.zzww;
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vec3 p0 = vec3(a0.xy, h.x);
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vec3 p1 = vec3(a0.zw, h.y);
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vec3 p2 = vec3(a1.xy, h.z);
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vec3 p3 = vec3(a1.zw, h.w);
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vec4 norm = taylor_inv_sqrt(vec4(dot(p0, p0), dot(p1, p1), dot(p2, p2), dot(p3, p3)));
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p0 *= norm.x;
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p1 *= norm.y;
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p2 *= norm.z;
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p3 *= norm.w;
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vec4 m = max(0.6 - vec4(dot(x0, x0), dot(x1, x1), dot(x2, x2), dot(x3, x3)), 0.0);
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m = m * m;
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return 42.0 * dot(m * m, vec4(dot(p0, x0), dot(p1, x1), dot(p2, x2), dot(p3, x3)));
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}
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