66 lines
1.8 KiB
GLSL
66 lines
1.8 KiB
GLSL
#ifdef GL_ES
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precision mediump float;
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#endif
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// Tweaked from http://glsl.heroku.com/e#6051.0
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// Posted by Trisomie21 : 2D noise experiment (pan/zoom)
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//
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// failed attempt at faking caustics
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//
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uniform mat3 outputToWorld;
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uniform vec4 color;
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uniform float time;
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vec4 textureRND2D(vec2 uv){
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uv = floor(uv);
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float v = uv.x+uv.y*1e3;
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// Build space-specific corner values
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vec4 res = fract(1e5*sin(vec4(v*1e-2, (v+1.)*1e-2, (v+1e3)*1e-2, (v+1e3+1.)*1e-2)));
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// Add 'sawtooth-like' wavefronts evolution
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return 2.0 * abs(fract(res + vec4(time * .03)) - 0.5);
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}
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float noise(vec2 p) {
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vec4 r = textureRND2D(p); // Noise values at cell corners
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vec2 f = fract(p);
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f = f*f*(3.0-2.0*f); // aka the smoothstep() builtin function
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return (mix(mix(r.x, r.y, f.x), mix(r.z, r.w, f.x), f.y));
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}
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float buildColor(vec2 p) {
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p += noise(p); // Noising p itself first. This helps
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// preventing grid-like patterns.
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float v = 1.0 - abs(pow(abs(noise(p) - 0.5), 0.75)) * 1.7; // Lots of magical constants o_o?
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return v;
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}
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const float SPEED = .15;
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void main( void ) {
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vec2 p = (outputToWorld * vec3(gl_FragCoord.xy, 1.0)).xy;
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float c1 = buildColor(p*.03 + time * SPEED);
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float c2 = buildColor(p*.03 - time * SPEED);
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float c3 = buildColor(p*.02 - time * SPEED);
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float c4 = buildColor(p*.02 + time * SPEED);
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float cf = pow(c1*c2*c3*c4+0.5,6.); // Yep this is bad. Explicitly
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// dependent on the 4 above. Better?
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vec3 c = vec3(cf);
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gl_FragColor = vec4(c, 0.0) + color;
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gl_FragColor.rgb *= gl_FragColor.a; // Premultiplication
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}
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