mirror of
https://github.com/patriciogonzalezvivo/thebookofshaders
synced 2024-11-03 23:15:23 +00:00
65 lines
1.9 KiB
GLSL
65 lines
1.9 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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//
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// Description : Array and textureless GLSL 2D simplex noise function.
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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 :
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// 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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vec2 mod289(vec2 x) { return x - floor(x * (1.0 / 289.0)) * 289.0; }
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vec3 permute(vec3 x) { return mod289(((x*34.0)+1.0)*x); }
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float snoise(vec2 v) {
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const vec4 C = vec4(0.211324865405187,
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0.366025403784439,
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-0.577350269189626,
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0.024390243902439);
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vec2 i = floor(v + dot(v, C.yy) );
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vec2 x0 = v - i + dot(i, C.xx);
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vec2 i1 = vec2(0.0);
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i1 = (x0.x > x0.y)? vec2(1.0, 0.0):vec2(0.0, 1.0);
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vec4 x12 = x0.xyxy + C.xxzz;
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x12.xy -= i1;
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i = mod289(i);
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vec3 p = permute(
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permute( i.y + vec3(0.0, i1.y, 1.0))
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+ i.x + vec3(0.0, i1.x, 1.0 ));
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vec3 m = max(0.5 - vec3(
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dot(x0,x0),
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dot(x12.xy,x12.xy),
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dot(x12.zw,x12.zw)
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), 0.0);
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m = m*m ;
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m = m*m ;
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vec3 x = 2.0 * fract(p * C.www) - 1.0;
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vec3 h = abs(x) - 0.5;
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vec3 ox = floor(x + 0.5);
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vec3 a0 = x - ox;
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m *= 1.79284291400159 - 0.85373472095314 * (a0*a0+h*h);
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vec3 g = vec3(0.0);
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g.x = a0.x * x0.x + h.x * x0.y;
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g.yz = a0.yz * x12.xz + h.yz * x12.yw;
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return 130.0 * dot(m, g);
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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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vec3 color = vec3(0.0);
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vec2 pos = vec2(st*10.);
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color = vec3(snoise(pos)*.5+.5);
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gl_FragColor = vec4(color,1.0);
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}
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