mirror of
https://github.com/patriciogonzalezvivo/thebookofshaders
synced 2024-11-11 13:10:57 +00:00
e58dec55ee
in four shaders a function that implements gradient noise was labeled as value noise and linked to IQ's value noise example on shadertoy. this pr labels that function as gradient noise and instead links to IQ's gradient noise example on shadertoy.
136 lines
4.0 KiB
GLSL
136 lines
4.0 KiB
GLSL
#ifdef GL_ES
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precision mediump float;
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#endif
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uniform vec2 u_resolution;
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uniform vec2 u_mouse;
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uniform float u_time;
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vec2 random2(vec2 st){
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st = vec2( dot(st,vec2(127.1,311.7)),
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dot(st,vec2(269.5,183.3)) );
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return -1.0 + 2.0*fract(sin(st)*43758.5453123);
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}
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// Gradient Noise by Inigo Quilez - iq/2013
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// https://www.shadertoy.com/view/XdXGW8
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float noise(vec2 st) {
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vec2 i = floor(st);
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vec2 f = fract(st);
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vec2 u = f*f*(3.0-2.0*f);
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return mix( mix( dot( random2(i + vec2(0.0,0.0) ), f - vec2(0.0,0.0) ),
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dot( random2(i + vec2(1.0,0.0) ), f - vec2(1.0,0.0) ), u.x),
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mix( dot( random2(i + vec2(0.0,1.0) ), f - vec2(0.0,1.0) ),
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dot( random2(i + vec2(1.0,1.0) ), f - vec2(1.0,1.0) ), u.x), u.y);
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}
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vec2 tile(vec2 _st, float _zoom){
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_st *= _zoom;
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return fract(_st);
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}
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float X(vec2 _st, float _width){
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float pct0 = smoothstep(_st.x-_width,_st.x,_st.y);
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pct0 *= 1.-smoothstep(_st.x,_st.x+_width,_st.y);
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float pct1 = smoothstep(_st.x-_width,_st.x,1.0-_st.y);
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pct1 *= 1.-smoothstep(_st.x,_st.x+_width,1.0-_st.y);
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return pct0+pct1;
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}
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//
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// Description : Array and textureless GLSL 2D/3D/4D simplex
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// noise functions.
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// Author : Ian McEwan, Ashima Arts.
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// Maintainer : ijm
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// Lastmod : 20110822 (ijm)
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// License : Copyright (C) 2011 Ashima Arts. All rights reserved.
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// Distributed under the MIT License. See LICENSE file.
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// https://github.com/ashima/webgl-noise
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//
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vec3 mod289(vec3 x) { return x - floor(x * (1.0 / 289.0)) * 289.0; }
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vec4 mod289(vec4 x) { return x - floor(x * (1.0 / 289.0)) * 289.0; }
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vec4 permute(vec4 x) { return mod289(((x*34.0)+1.0)*x); }
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vec4 taylorInvSqrt(vec4 r) { return 1.79284291400159 - 0.85373472095314 * r; }
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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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// First corner
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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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// Other corners
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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; // 2.0*C.x = 1/3 = C.y
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vec3 x3 = x0 - D.yyy; // -1.0+3.0*C.x = -0.5 = -D.y
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// Permutations
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i = mod289(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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// Gradients: 7x7 points over a square, mapped onto an octahedron.
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// The ring size 17*17 = 289 is close to a multiple of 49 (49*6 = 294)
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float n_ = 0.142857142857; // 1.0/7.0
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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); // mod(p,7*7)
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vec4 x_ = floor(j * ns.z);
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vec4 y_ = floor(j - 7.0 * x_ ); // mod(j,N)
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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));
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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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//Normalise gradients
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vec4 norm = taylorInvSqrt(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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// Mix final noise value
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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),
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dot(p2,x2), dot(p3,x3) ) );
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}
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void main() {
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vec2 st = gl_FragCoord.xy/u_resolution.xy;
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st.x *= u_resolution.x/u_resolution.y;
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float grid = 1.0-X(tile(st,15.+snoise(vec3(st,u_time*.1))),0.05);
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gl_FragColor = vec4(vec3(grid),1.0);
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}
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