mirror of
https://github.com/patriciogonzalezvivo/thebookofshaders
synced 2024-11-09 19:10:24 +00:00
108 lines
3.5 KiB
GLSL
108 lines
3.5 KiB
GLSL
// Author @patriciogv - 2015
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// http://patriciogonzalezvivo.com
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#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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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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float scale = 10.0;
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st *= scale;
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float t = u_time*0.3;
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vec2 offset = vec2(1.)/u_resolution.xy;
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float center = snoise(vec3(st.x, st.y, t));
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float topLeft = snoise(vec3(st.x - offset.x, st.y - offset.y, t));
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float left = snoise(vec3(st.x - offset.x, st.y, t));
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float bottomLeft = snoise(vec3(st.x - offset.x, st.y + offset.y, t));
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float top = snoise(vec3(st.x, st.y - offset.y, t));
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float bottom = snoise(vec3(st.x, st.y + offset.y, t));
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float topRight = snoise(vec3(st.x + offset.x, st.y - offset.y, t));
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float right = snoise(vec3(st.x + offset.x, st.y, t));
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float bottomRight= snoise(vec3(st.x + offset.x, st.y + offset.y, t));
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float dX = topRight + 2.0 * right + bottomRight - topLeft - 2.0 * left - bottomLeft;
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float dY = bottomLeft + 2.0 * bottom + bottomRight - topLeft - 2.0 * top - topRight;
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vec3 N = normalize(vec3( dX, dY, 0.01))*.5+.5;
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gl_FragColor= vec4(N,1.);
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} |